WorldWideScience

Sample records for electricity reliability risk

  1. Reliability risks during the transition to competitive electricity markets

    International Nuclear Information System (INIS)

    Hughes, J.P.

    2005-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Alvehag, Karin

    2011-07-01

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

  3. Hawaii Electric System Reliability

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-08-01

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

  4. Hawaii electric system reliability.

    Energy Technology Data Exchange (ETDEWEB)

    Silva Monroy, Cesar Augusto; Loose, Verne William

    2012-09-01

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

  5. INCREASED RELIABILITY OF ELECTRIC BLASTING

    OpenAIRE

    Kashuba, Oleh Ivanovych; Skliarov, L I; Skliarov, A L

    2017-01-01

    The problems of improving reliability of an electric blasting method using electric detonators with nichrome filament bridges. It was revealed that in the calculation of the total resistance of the explosive network it is necessary to increase to 24% of the nominal value

  6. 78 FR 41339 - Electric Reliability Organization Proposal To Retire Requirements in Reliability Standards

    Science.gov (United States)

    2013-07-10

    ...] Electric Reliability Organization Proposal To Retire Requirements in Reliability Standards AGENCY: Federal... Reliability Standards identified by the North American Electric Reliability Corporation (NERC), the Commission-certified Electric Reliability Organization. FOR FURTHER INFORMATION CONTACT: Kevin Ryan (Legal Information...

  7. Risk analysis and reliability

    International Nuclear Information System (INIS)

    Uppuluri, V.R.R.

    1979-01-01

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

  8. Reliability evaluation of deregulated electric power systems for planning applications

    International Nuclear Information System (INIS)

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

    2008-01-01

    In a deregulated electric power utility industry in which a competitive electricity market can influence system reliability, market risks cannot be ignored. This paper (1) proposes an analytical probabilistic model for reliability evaluation of competitive electricity markets and (2) develops a methodology for incorporating the market reliability problem into HLII reliability studies. A Markov state space diagram is employed to evaluate the market reliability. Since the market is a continuously operated system, the concept of absorbing states is applied to it in order to evaluate the reliability. The market states are identified by using market performance indices and the transition rates are calculated by using historical data. The key point in the proposed method is the concept that the reliability level of a restructured electric power system can be calculated using the availability of the composite power system (HLII) and the reliability of the electricity market. Two case studies are carried out over Roy Billinton Test System (RBTS) to illustrate interesting features of the proposed methodology

  9. Risk and reliability allocation to risk control

    International Nuclear Information System (INIS)

    Vojnovic, D.; Kozuh, M.

    1992-01-01

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

  10. 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...

  11. Reliability planning in distributed electric energy systems

    Energy Technology Data Exchange (ETDEWEB)

    Kahn, E.

    1978-10-01

    The goal of this paper is to develop tools for technology evaluation that address questions involving the economics of large-scale systems. The kind of cost discussed usually involves some dynamic aspect of the energy system. In particular, such properties as flexibility, stability, and resilience are features of entire systems. Special attention must be paid to the question of reliability, i.e., availability on demand. The storage problem and the planning for reliability in utility systems are the subjects of this paper. The introductory chapter addresses preliminary definitions--reliability planning, uncertainty, resilience, and other sensitivities. The study focuses on the contrast between conventional power generation technologies with controllable output and intermittent resources such as wind and solar electric conversion devices. The system studied is a stylized representation of California conditions. Significant differences were found in reliability planning requirements (and therefore costs) for systems dominated by central station plants as opposed to those dominated by intermittent resource technologies. It is argued that existing hydroelectric facilities need re-optimization. These plants provide the only currently existing bulk power storage in electric energy systems. 38 references. (MCW)

  12. Novel approach for evaluation of service reliability for electricity customers

    Institute of Scientific and Technical Information of China (English)

    JIANG; John; N

    2009-01-01

    Understanding reliability value for electricity customer is important to market-based reliability management. This paper proposes a novel approach to evaluate the reliability for electricity customers by using indifference curve between economic compensation for power interruption and service reliability of electricity. Indifference curve is formed by calculating different planning schemes of network expansion for different reliability requirements of customers, which reveals the information about economic values for different reliability levels for electricity customers, so that the reliability based on market supply demand mechanism can be established and economic signals can be provided for reliability management and enhancement.

  13. 76 FR 73608 - Reliability Technical Conference, North American Electric Reliability Corporation, Public Service...

    Science.gov (United States)

    2011-11-29

    ... or municipal authority play in forming your bulk power system reliability plans? b. Do you support..., North American Electric Reliability Corporation (NERC) Nick Akins, CEO of American Electric Power (AEP..., EL11-62-000] Reliability Technical Conference, North American Electric Reliability Corporation, Public...

  14. Alberta's electricity policy framework : competitive, reliable, sustainable

    International Nuclear Information System (INIS)

    2005-01-01

    This paper described public policies in Alberta that are implemented to create an electric power industry that is competitive, reliable and sustainable. The success of Alberta's competitive electric market framework can be attributed to new investment in the industry along with new players participating in the electricity market. The Alberta Department of Energy is committed to a competitive wholesale market model and to competitively-priced electricity. The Alberta Energy and Utilities Board supports the development of Alberta's vast resource base and facilitates power generation development and support through transmission development and an interconnected transmission system. A wholesale market Policy Task Force was established in 2005 to review the progress in Alberta's electric market design and its competitive retail market. This paper outlines a policy framework which addresses design of the regulated rate option post July 1, 2006; short-term adequacy; and long-term adequacy. Other inter-related market issues were also discussed, such as operating reserves market, transmission services, interties, demand response, balancing pool assets, credit, market power mitigation, and wind generation. It is expected that the recommendations in this paper will be implemented as quickly as possible following amendments to regulations or ISO rules. tabs., figs.

  15. Will British weather provide reliable electricity?

    International Nuclear Information System (INIS)

    Oswald, James; Raine, Mike; Ashraf-Ball, Hezlin

    2008-01-01

    There has been much academic debate on the ability of wind to provide a reliable electricity supply. The model presented here calculates the hourly power delivery of 25 GW of wind turbines distributed across Britain's grid, and assesses power delivery volatility and the implications for individual generators on the system. Met Office hourly wind speed data are used to determine power output and are calibrated using Ofgem's published wind output records. There are two main results. First, the model suggests that power swings of 70% within 12 h are to be expected in winter, and will require individual generators to go on or off line frequently, thereby reducing the utilisation and reliability of large centralised plants. These reductions will lead to increases in the cost of electricity and reductions in potential carbon savings. Secondly, it is shown that electricity demand in Britain can reach its annual peak with a simultaneous demise of wind power in Britain and neighbouring countries to very low levels. This significantly undermines the case for connecting the UK transmission grid to neighbouring grids. Recommendations are made for improving 'cost of wind' calculations. The authors are grateful for the sponsorship provided by The Renewable Energy Foundation

  16. 18 CFR 39.3 - Electric Reliability Organization certification.

    Science.gov (United States)

    2010-04-01

    ... operators of the Bulk-Power System, and other interested parties for improvement of the Electric Reliability... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Electric Reliability..., Reliability Standards that provide for an adequate level of reliability of the Bulk-Power System, and (2) Has...

  17. 77 FR 39858 - Revisions to Electric Reliability Organization Definition of Bulk Electric System and Rules of...

    Science.gov (United States)

    2012-07-05

    ... bulk electric system reliability through steady state power flow, and contain a transient stability... Commission 18 CFR Part 40 Revisions to Electric Reliability Organization Definition of Bulk Electric System... definition of ``bulk electric system'' developed by the North American Electric Reliability Corporation (NERC...

  18. Research on the Reliability Testing of Electrical Automation Control Equipment

    OpenAIRE

    Yongjie Luo

    2014-01-01

    According to the author’s many years’ work experience, this paper first discusses the concepts of electrical automation control equipment reliability testing, and then analyzes the test method of electrical automation control equipment reliability testing, finally, on this basis, this article discusses how to determine the reliability test method of electrical automation control equipment. Results of this study will provide a useful reference for electrical automation control equipment reliab...

  19. 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...

  20. 76 FR 66055 - North American Electric Reliability Corporation; Order Approving Interpretation of Reliability...

    Science.gov (United States)

    2011-10-25

    ...\\ Mandatory Reliability Standards for the Bulk-Power System, Order No. 693, FERC Stats. & Regs. ] 31,242... materially affected'' by Bulk-Power System reliability may request an interpretation of a Reliability... Electric Reliability Corporation; Order Approving Interpretation of Reliability Standard; Before...

  1. 75 FR 72909 - Revision to Electric Reliability Organization Definition of Bulk Electric System

    Science.gov (United States)

    2010-11-26

    ... Bulk-Power System. See Rules Concerning Certification of the Electric Reliability Organization; and... Bulk-Power System in North America because it protects the reliability of the bulk electric system and... Electric Reliability Organization Definition of Bulk Electric System; Final Rule #0;#0;Federal Register...

  2. 78 FR 29209 - Revisions to Electric Reliability Organization Definition of Bulk Electric System and Rules of...

    Science.gov (United States)

    2013-05-17

    ... Commission 18 CFR Part 40 Revisions to Electric Reliability Organization Definition of Bulk Electric System... local distribution'' as set forth in the Federal Power Act (FPA). \\1\\ Revisions to Electric Reliability... Reliability Organization Definition of Bulk Electric System, Order No. 743, 133 FERC ] 61,150, at P 16 (2010...

  3. 76 FR 16263 - Revision to Electric Reliability Organization Definition of Bulk Electric System

    Science.gov (United States)

    2011-03-23

    ...; Order No. 743-A] Revision to Electric Reliability Organization Definition of Bulk Electric System AGENCY... certain provisions of the Final Rule. Order No. 743 directed the Electric Reliability Organization (ERO) to revise the definition of the term ``bulk electric system'' through the ERO's Reliability Standards...

  4. North American Electric Reliability Council (NERC) Reliability Coordinators

    Data.gov (United States)

    Department of Homeland Security — ERC is an international regulatory authority that works to improve the reliability of the bulk power system in North America. NERC works with many different regional...

  5. 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...

  6. Reevaluating Interrater Reliability in Offender Risk Assessment

    NARCIS (Netherlands)

    van der Knaap, L.M.; Leenarts, L.E.W.; Born, M.P.; Oosterveld, P.

    2012-01-01

    Offender risk and needs assessment, one of the pillars of the risk-need-responsivity model of offender rehabilitation, usually depends on raters assessing offender risk and needs. The few available studies of interrater reliability in offender risk assessment are, however, limited in the

  7. Reevaluating Interrater Reliability in Offender Risk Assessment

    Science.gov (United States)

    van der Knaap, Leontien M.; Leenarts, Laura E. W.; Born, Marise Ph.; Oosterveld, Paul

    2012-01-01

    Offender risk and needs assessment, one of the pillars of the risk-need-responsivity model of offender rehabilitation, usually depends on raters assessing offender risk and needs. The few available studies of interrater reliability in offender risk assessment are, however, limited in the generalizability of their results. The present study…

  8. Reliability Evaluation for Optimizing Electricity Supply in a Developing Country

    Directory of Open Access Journals (Sweden)

    Mark Ndubuka NWOHU

    2007-09-01

    Full Text Available The reliability standards for electricity supply in a developing country, like Nigeria, have to be determined on past engineering principles and practice. Because of the high demand of electrical power due to rapid development, industrialization and rural electrification; the economic, social and political climate in which the electric power supply industry now operates should be critically viewed to ensure that the production of electrical power should be augmented and remain uninterrupted. This paper presents an economic framework that can be used to optimize electric power system reliability. Finally the cost models are investigated to take into account the economic analysis of system reliability, which can be periodically updated to improve overall reliability of electric power system.

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

    International Nuclear Information System (INIS)

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

    1993-01-01

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

  10. Demand Response Application forReliability Enhancement in Electricity Market

    OpenAIRE

    Romera Pérez, Javier

    2015-01-01

    The term reliability is related with the adequacy and security during operation of theelectric power system, supplying the electricity demand over time and saving thepossible contingencies because every inhabitant needs to be supplied with electricity intheir day to day. Operating the system in this way entails spending money. The first partof the project is going to be an analysis of the reliability and the economic impact of it.During the last decade, electric utilities and companies had be...

  11. 76 FR 66057 - North American Electric Reliability Corporation; Order Approving Regional Reliability Standard

    Science.gov (United States)

    2011-10-25

    ... Reliability Standard that is necessitated by a physical difference in the Bulk-Power System.\\7\\ \\7\\ Order No... Reliability Standards for the Bulk-Power System, Order No. 693, FERC Stats. & Regs. ] 31,242, order on reh'g... electric system event analyses and thereby improve system reliability by promoting improved system design...

  12. Systems reliability in high risk situations

    International Nuclear Information System (INIS)

    Hunns, D.M.

    1974-12-01

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

  13. Reliability Evaluation for Optimizing Electricity Supply in a Developing Country

    OpenAIRE

    Mark Ndubuka NWOHU

    2007-01-01

    The reliability standards for electricity supply in a developing country, like Nigeria, have to be determined on past engineering principles and practice. Because of the high demand of electrical power due to rapid development, industrialization and rural electrification; the economic, social and political climate in which the electric power supply industry now operates should be critically viewed to ensure that the production of electrical power should be augmented and remain uninterrupted. ...

  14. Distribution-level electricity reliability: Temporal trends using statistical analysis

    International Nuclear Information System (INIS)

    Eto, Joseph H.; LaCommare, Kristina H.; Larsen, Peter; Todd, Annika; Fisher, Emily

    2012-01-01

    This paper helps to address the lack of comprehensive, national-scale information on the reliability of the U.S. electric power system by assessing trends in U.S. electricity reliability based on the information reported by the electric utilities on power interruptions experienced by their customers. The research analyzes up to 10 years of electricity reliability information collected from 155 U.S. electric utilities, which together account for roughly 50% of total U.S. electricity sales. We find that reported annual average duration and annual average frequency of power interruptions have been increasing over time at a rate of approximately 2% annually. We find that, independent of this trend, installation or upgrade of an automated outage management system is correlated with an increase in the reported annual average duration of power interruptions. We also find that reliance on IEEE Standard 1366-2003 is correlated with higher reported reliability compared to reported reliability not using the IEEE standard. However, we caution that we cannot attribute reliance on the IEEE standard as having caused or led to higher reported reliability because we could not separate the effect of reliance on the IEEE standard from other utility-specific factors that may be correlated with reliance on the IEEE standard. - Highlights: ► We assess trends in electricity reliability based on the information reported by the electric utilities. ► We use rigorous statistical techniques to account for utility-specific differences. ► We find modest declines in reliability analyzing interruption duration and frequency experienced by utility customers. ► Installation or upgrade of an OMS is correlated to an increase in reported duration of power interruptions. ► We find reliance in IEEE Standard 1366 is correlated with higher reported reliability.

  15. Computer-aided reliability and risk assessment

    International Nuclear Information System (INIS)

    Leicht, R.; Wingender, H.J.

    1989-01-01

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

  16. 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

  17. Reliability and validity of risk analysis

    International Nuclear Information System (INIS)

    Aven, Terje; Heide, Bjornar

    2009-01-01

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

  18. Puget Sound area electric reliability plan

    Energy Technology Data Exchange (ETDEWEB)

    1991-09-01

    Various conservation, load management, and fuel switching programs were considered as ways to reduce or shift system peak load. These programs operate at the end-use level, such as residential water heat. Figure D-1a shows what electricity consumption for water heat looks like on normal and extreme peak days. Load management programs, such as water heat control, are designed to reduce electricity consumption at the time of system peak. On the coldest day in average winter, system load peaks near 8:00 a.m. In a winter with extremely cold weather, electricity consumption increases fr all hours, and the system peak shifts to later in the morning. System load shapes in the Puget Sound area are shown in Figure D-1b for a normal winter peak day (February 2, 1988) and extreme peak day (February 3, 1989). Peak savings from any program are calculated to be the reduction in loads on the entire system at the hour of system peak. Peak savings for all programs are measured at 8:00 a.m. on a normal peak day and 9:00 a.m. on an extreme peak day. On extremely cold day, some water heat load shifts to much later in the morning, with less load available for shedding at the time of system peak. Models of hourly end-use consumption were constructed to simulate the impact of conservation, land management, and fuel switching programs on electricity consumption. Javelin, a time-series simulating package for personal computers, was chosen for the hourly analysis. Both a base case and a program case were simulated. 15 figs., 7 tabs.

  19. FUNDAMENTALS OF RELIABILITY OF ELECTRIC POWER SYSTEM AND EQUIPMENT

    OpenAIRE

    Engr. Anumaka; Michael Chukwukadibia

    2011-01-01

    Today, the electric power system consists of complex interconnected network which are prone to different problems that militates against the reliability of the power system. Inadequate reliability in the power system causes problems such as high failure rate of power system installations and consumer equipment, transient and intransient faults, symmetrical faults etc. This paper provides an extensive review of the powers system and equipment reliability and related failure patterns in equipment.

  20. Methodology for allocating reliability and risk

    International Nuclear Information System (INIS)

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

    1986-05-01

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

  1. CERTS: Consortium for Electric Reliability Technology Solutions - Research Highlights

    Energy Technology Data Exchange (ETDEWEB)

    Eto, Joseph

    2003-07-30

    Historically, the U.S. electric power industry was vertically integrated, and utilities were responsible for system planning, operations, and reliability management. As the nation moves to a competitive market structure, these functions have been disaggregated, and no single entity is responsible for reliability management. As a result, new tools, technologies, systems, and management processes are needed to manage the reliability of the electricity grid. However, a number of simultaneous trends prevent electricity market participants from pursuing development of these reliability tools: utilities are preoccupied with restructuring their businesses, research funding has declined, and the formation of Independent System Operators (ISOs) and Regional Transmission Organizations (RTOs) to operate the grid means that control of transmission assets is separate from ownership of these assets; at the same time, business uncertainty, and changing regulatory policies have created a climate in which needed investment for transmission infrastructure and tools for reliability management has dried up. To address the resulting emerging gaps in reliability R&D, CERTS has undertaken much-needed public interest research on reliability technologies for the electricity grid. CERTS' vision is to: (1) Transform the electricity grid into an intelligent network that can sense and respond automatically to changing flows of power and emerging problems; (2) Enhance reliability management through market mechanisms, including transparency of real-time information on the status of the grid; (3) Empower customers to manage their energy use and reliability needs in response to real-time market price signals; and (4) Seamlessly integrate distributed technologies--including those for generation, storage, controls, and communications--to support the reliability needs of both the grid and individual customers.

  2. Influence of reliability of the relay protection to the whole reliability of electric power systems

    International Nuclear Information System (INIS)

    Stojanovski, Ljupcho I.

    2001-01-01

    The influence of the reliability of the elements of relay protection up today analyses of the reliability on electric power systems, very rare has been taken into consideration, in other words, in these analyses it is assumed that the reliability of the protection has value one. In this work an attempt is that through modelling of individual types of protection of the elements of high-voltage systems to make calculation to the influence of the reliability of the relay protection on the total reliability of the high-voltage systems.(Author)

  3. Reliability and risk analysis methods research plan

    International Nuclear Information System (INIS)

    1984-10-01

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

  4. 75 FR 14097 - Revision to Electric Reliability Organization Definition of Bulk Electric System

    Science.gov (United States)

    2010-03-24

    ... electrical failure of a 138 kV motor operated switch on a 138 kV-13 kV transformer located in the ReliabilityFirst region resulted in the tripping of two transformers, one due to the electrical failure and the... Commission 18 CFR Part 40 [Docket No. RM09-18-000; 130 FERC ] 61,204] Revision to Electric Reliability...

  5. A COMPUTERIZED DIAGNOSTIC COMPLEX FOR RELIABILITY TESTING OF ELECTRIC MACHINES

    Directory of Open Access Journals (Sweden)

    O.О. Somka

    2015-06-01

    Full Text Available Purpose. To develop a diagnostic complex meeting the criteria and requirements for carrying out accelerated reliability test and realizing the basic modes of electric machines operation and performance of the posed problems necessary in the process of such test. Methodology. To determine and forecast the indices of electric machines reliability in accordance with the statistic data of repair plants we have conditionally divided them into structural parts that are most likely to fail. We have preliminarily assessed the state of each of these parts, which includes revelation of faults and deviations of technical and geometric parameters. We have determined the analyzed electric machine controlled parameters used for assessment of quantitative characteristics of reliability of these parts and electric machines on the whole. Results. As a result of the research, we have substantiated the structure of a computerized complex for electric machines reliability test. It allows us to change thermal and vibration actions without violation of the physics of the processes of aging and wearing of the basic structural parts and elements material. The above mentioned makes it possible to considerably reduce time spent on carrying out electric machines reliability tests and improve trustworthiness of the data obtained as a result of their performance. Originality. A special feature of determination of the controlled parameters consists in removal of vibration components in the idle mode and after disconnection of the analyzed electric machine from the power supply with the aim of singling out the vibration electromagnetic component, fixing the degree of sparking and bend of the shaft by means of phototechnique and local determination of structural parts temperature provided by corresponding location of thermal sensors. Practical value. We have offered a scheme of location of thermal and vibration sensors, which allows improvement of parameters measuring accuracy

  6. Human reliability assessment and probabilistic risk assessment

    International Nuclear Information System (INIS)

    Embrey, D.E.; Lucas, D.A.

    1989-01-01

    Human reliability assessment (HRA) is used within Probabilistic Risk Assessment (PRA) to identify the human errors (both omission and commission) which have a significant effect on the overall safety of the system and to quantify the probability of their occurrence. There exist a variey of HRA techniques and the selection of an appropriate one is often difficult. This paper reviews a number of available HRA techniques and discusses their strengths and weaknesses. The techniques reviewed include: decompositional methods, time-reliability curves and systematic expert judgement techniques. (orig.)

  7. Applying reliability analysis to design electric power systems for More-electric aircraft

    Science.gov (United States)

    Zhang, Baozhu

    The More-Electric Aircraft (MEA) is a type of aircraft that replaces conventional hydraulic and pneumatic systems with electrically powered components. These changes have significantly challenged the aircraft electric power system design. This thesis investigates how reliability analysis can be applied to automatically generate system topologies for the MEA electric power system. We first use a traditional method of reliability block diagrams to analyze the reliability level on different system topologies. We next propose a new methodology in which system topologies, constrained by a set reliability level, are automatically generated. The path-set method is used for analysis. Finally, we interface these sets of system topologies with control synthesis tools to automatically create correct-by-construction control logic for the electric power system.

  8. Reliability modeling of Clinch River breeder reactor electrical shutdown systems

    International Nuclear Information System (INIS)

    Schatz, R.A.; Duetsch, K.L.

    1974-01-01

    The initial simulation of the probabilistic properties of the Clinch River Breeder Reactor Plant (CRBRP) electrical shutdown systems is described. A model of the reliability (and availability) of the systems is presented utilizing Success State and continuous-time, discrete state Markov modeling techniques as significant elements of an overall reliability assessment process capable of demonstrating the achievement of program goals. This model is examined for its sensitivity to safe/unsafe failure rates, sybsystem redundant configurations, test and repair intervals, monitoring by reactor operators; and the control exercised over system reliability by design modifications and the selection of system operating characteristics. (U.S.)

  9. Managing Risks in Electrical Infrastructure Assets from a Strategic Perspective

    NARCIS (Netherlands)

    Zhuang, Q.

    2015-01-01

    Should risks always be quantified before being managed? The answer is “yes” in the opinion of most asset managers in today’s electricity transmission and distribution companies, but “no” in modern theories of risk management. When the risks refer to reliability hazards of high-voltage assets, the

  10. Reliability & availability of wind turbine electrical & electronic components

    NARCIS (Netherlands)

    Tavner, P.; Faulstich, S.; Hahn, B.; Bussel, van G.J.W.

    2010-01-01

    Recent analysis of European onshore wind turbine reliability data has shown that whilst wind turbine mechanical subassemblies tend to have relatively low failure rates but long downtimes, electrical and electronic subassemblies have relatively high failure rates and short downtimes. For onshore wind

  11. Load As A Reliability Resource in the Restructured Electricity Market

    Energy Technology Data Exchange (ETDEWEB)

    Kueck, J.D.

    2002-06-10

    Recent electricity price spikes are painful reminders of the value that meaningful demand-side responses could bring to the restructuring US electricity system. Review of the aggregate offers made by suppliers confirms that even a modest increase in demand elasticity could dramatically reduce these extremes in price volatility. There is a strong need for dramatically increased customer participation in these markets to enhance system reliability and reduce price volatility. Indeed, allowing customers to manage their loads in response to system conditions might be thought of as the ultimate reliability resource. Most would agree that meaningful demand-side responses to price are the hallmark of a well-functioning competitive market [1]. Yet, in today's markets for electricity, little or no such response is evident. The reason is simple: customers currently do not experience directly the time-varying costs of their consumption decisions. Consequently, they have no incentive to modify these decisions in ways that might enhance system reliability or improve the efficiency of the markets in which electricity is traded. Increased customer participation is a necessary step in the evolution toward more efficient markets for electricity and ancillary services. This scoping report provides a three-part assessment of the current status of efforts to enhance the ability of customer's load to participate in competitive markets with a specific focus on the role of customer loads in enhancing electricity system reliability. First, this report considers the definitions of electricity-reliability-enhancing ancillary services (Section 2) and a preliminary assessment of the ability of customer's loads to provide these services. Second, is a review a variety of programs in which load has been called on as a system reliability resource (Section 3). These experiences, drawn from both past and current utility and ISO programs, focus on programs triggered by system

  12. 75 FR 80391 - Electric Reliability Organization Interpretations of Interconnection Reliability Operations and...

    Science.gov (United States)

    2010-12-22

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

  13. Staff Report to the Secretary on Electricity Markets and Reliability

    Energy Technology Data Exchange (ETDEWEB)

    None

    2017-08-01

    Energy Secretary Rick Perry issued a memo in April of 2017 requesting a study and directing his staff to develop a report to include an assessment of the reliability and resilience of the electric grid and an overview of the evolution of electricity markets. Various factors have emerged over the past 15 years which have impacted power supply and demand in different ways. This study, prepared by experts throughout the Department, contains a comprehensive analysis of these factors and the corresponding data, and presents a series of recommendations meant to inform and guide policy makers, regulators, and the general public. Potential areas for further research are also presented.

  14. Managing relationships between electric power industry restructuring and grid reliability

    International Nuclear Information System (INIS)

    Thomas, R.J.

    2005-01-01

    The electricity system is a critical infrastructure, and its continued and reliable functioning is essential to the nation's economy and well-being. However, the inter-dependency of electricity networks is not completely understood. The economic impact of outages was discussed in this white paper. It was suggested that moving to a restructured environment has degraded the reliability of the bulk system. New institutional arrangements and approaches to information management are needed. It was suggested that reliability practices caused the 2003 blackout, and not technical failures. Uncertainties in the restructured market were discussed, as well as incentives to maintain system adequacy. Examples of deregulation in other countries were presented. Organizational complexities were reviewed, including the Federal Energy Regulatory Commission's (FERC) requirements and the new layers of complexity that have been added to the decision-making process in the light of restructuring. Planning and connectivity issues were reviewed. The need for design standards in power grid control centres was discussed. Difficulties in collecting data from different control centres were considered. Issues concerning the lack of investment in research and development were discussed, with particular reference to the urgent need for coordinated research programs. The looming manpower crisis in the electric power industry was also discussed. Recommendations included ensuring that the transmission system can support a market structure; building a national reliability centre; solving the manpower crisis; and testing market designs before deploying them. It was concluded that good engineering design principles, including experimental economic testing, should be required of any new electricity market design before authorizing its use. 31 refs., 1 tab., 6 figs

  15. 18 CFR 39.4 - Funding of the Electric Reliability Organization.

    Science.gov (United States)

    2010-04-01

    ... CERTIFICATION OF THE ELECTRIC RELIABILITY ORGANIZATION; AND PROCEDURES FOR THE ESTABLISHMENT, APPROVAL, AND ENFORCEMENT OF ELECTRIC RELIABILITY STANDARDS § 39.4 Funding of the Electric Reliability Organization. (a) Any... Reliability Organization. 39.4 Section 39.4 Conservation of Power and Water Resources FEDERAL ENERGY...

  16. Reliability payments to generation capacity in electricity markets

    International Nuclear Information System (INIS)

    Olsina, Fernando; Pringles, Rolando; Larisson, Carlos; Garcés, Francisco

    2014-01-01

    Electric power is a critical input to modern economies. Generation adequacy and security of supply in power systems running under competition are currently topics of high concern for consumers, regulators and governments. In a market setting, generation investments and adequacy can only be achieved by an appropriate regulatory framework that sets efficient remuneration to power capacity. Theoretically, energy-only electricity markets are efficient and no additional mechanism is needed. Nonetheless, the energy-only market design suffers from serious drawbacks. Therefore, jointly with the evolution of electricity markets, many remunerating mechanisms for generation capacity have been proposed. Explicit capacity payment was the first remunerating approach implemented and perhaps still the most applied. However, this price-based regulation has been applied no without severe difficulties and criticism. In this paper, a new reliability payment mechanism is envisioned. Capacity of each generating unit is paid according to its effective contribution to overall system reliability. The proposed scheme has many attractive features and preserves the theoretical efficiency properties of energy-only markets. Fairness, incentive compatibility, market power mitigation and settlement rules are investigated in this work. The article also examines the requirements for system data and models in order to implement the proposed capacity mechanism. A numerical example on a real hydrothermal system serves for illustrating the practicability of the proposed approach and the resulting reliability payments to the generation units. - Highlights: • A new approach for remunerating supply reliability provided by generation units is proposed. • The contribution of each generating unit to lessen power shortfalls is determined by simulations. • Efficiency, fairness and incentive compatibility of the proposed reliability payment are assessed

  17. Integrated Reliability and Risk Analysis System (IRRAS)

    International Nuclear Information System (INIS)

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

    1992-01-01

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

  18. Reliability and risk treatment centered maintenance

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  19. Reliability and risk treatment centered maintenance

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-10-15

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

  20. Reliability Electrical Power System of Hospital as Cold Standby System

    Directory of Open Access Journals (Sweden)

    Grabski Franciszek

    2016-07-01

    Full Text Available The probabilistic model of a hospital electrical power system consisting of mains, an emergency power system and the automatic transfer switch with the generator starter are discussed in this paper. The reliability model is semi-Markov process describing two different units renewable cold standby system and switch. The embedded Semi-Markov processes concept is applied for description of the system evolution. Time to failure of the system is represented by a random variable denoting the first passage time of the process from the given state to the subset of states. The appropriate theorems of the Semi-Markov processes theory allow us to evaluate the reliability function and some reliability characteristics.

  1. Basic Principles of Electrical Network Reliability Optimization in Liberalised Electricity Market

    Science.gov (United States)

    Oleinikova, I.; Krishans, Z.; Mutule, A.

    2008-01-01

    The authors propose to select long-term solutions to the reliability problems of electrical networks in the stage of development planning. The guide lines or basic principles of such optimization are: 1) its dynamical nature; 2) development sustainability; 3) integrated solution of the problems of network development and electricity supply reliability; 4) consideration of information uncertainty; 5) concurrent consideration of the network and generation development problems; 6) application of specialized information technologies; 7) definition of requirements for independent electricity producers. In the article, the major aspects of liberalized electricity market, its functions and tasks are reviewed, with emphasis placed on the optimization of electrical network development as a significant component of sustainable management of power systems.

  2. Analysis of dependent failures in risk assessment and reliability evaluation

    International Nuclear Information System (INIS)

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

    1983-01-01

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

  3. Reliability data collection and use in risk and availability assessment

    International Nuclear Information System (INIS)

    Colombari, V.

    1989-01-01

    For EuReDatA it is a prevailing objective to initiate and support contact between experts, companies and institutions active in reliability engineering and research. Main topics of this 6th EuReDatA Conference are: Reliability data banks; incidents data banks; common cause data; source and propagation of uncertainties; computer aided risk analysis; reliability and incidents data acquisition and processing; human reliability; probabilistic safety and availability assessment; feedback of reliability into system design; data fusion; reliability modeling and techniques; structural and mechanical reliability; consequence modeling; software and electronic reliability; reliability tests. Some conference papers are separately indexed in the database. (HP)

  4. Distribution reliability in the reformed New Zealand electricity industry

    International Nuclear Information System (INIS)

    McGlinchy, B. J.

    1997-01-01

    The process of deregulating the electric power industry in New Zealand, which began in 1984, and is now a fully competitive system, was described. The industry is not only fully competitive, but enjoys the distinction of being subject only to very light-handed regulation. The regulation requires each company within the industry to publish an annual financial statement, the rate of profit and some performance indicators including reliability indices. Companies also report on faults in lines and cables, and on a voluntary basis they contribute to a 'by cause' survey, using indicators developed by the Canadian Electricity Association. It is expected that the indices that will be developed from this data will be used as benchmarks for performance. The data could also be used for probability analysis in system expansion programs. 6 refs., 7 figs

  5. Puget Sound area electric reliability plan. Draft environmental impact statement

    Energy Technology Data Exchange (ETDEWEB)

    1991-09-01

    The Puget Sound Area Electric Reliability Plan Draft Environmental Impact Statement (DEIS) identifies the alternatives for solving a power system problem in the Puget Sound area. This Plan is undertaken by Bonneville Power Administration (BPA), Puget Sound Power & Light, Seattle City Light, Snohomish Public Utility District No. 1 (PUD), and Tacoma Public Utilities. The Plan consists of potential actions in Puget Sound and other areas in the State of Washington. A specific need exists in the Puget Sound area for balance between east-west transmission capacity and the increasing demand to import power generated east of the Cascades. At certain times of the year, there is more demand for power than the electric system can supply in the Puget Sound area. This high demand, called peak demand, occurs during the winter months when unusually cold weather increases electricity use for heating. The existing power system can supply enough power if no emergencies occur. However, during emergencies, the system will not operate properly. As demand grows, the system becomes more strained. To meet demand, the rate of growth of demand must be reduced or the ability to serve the demand must be increased, or both. The plan to balance Puget Sound`s power demand and supply has these purposes: The plan should define a set of actions that would accommodate ten years of load growth (1994--2003). Federal and State environmental quality requirements should be met. The plan should be consistent with the plans of the Northwest Power Planning Council. The plan should serve as a consensus guideline for coordinated utility action. The plan should be flexible to accommodate uncertainties and differing utility needs. The plan should balance environmental impacts and economic costs. The plan should provide electric system reliability consistent with customer expectations. 29 figs., 24 tabs.

  6. Puget Sound Area Electric Reliability Plan : Draft Environmental Impact State.

    Energy Technology Data Exchange (ETDEWEB)

    United States. Bonneville Power Administration.

    1991-09-01

    The Puget Sound Area Electric Reliability Plan Draft Environmental Impact Statement (DEIS) identifies the alternatives for solving a power system problem in the Puget Sound area. This Plan is undertaken by Bonneville Power Administration (BPA), Puget Sound Power Light, Seattle City Light, Snohomish Public Utility District No. 1 (PUD), and Tacoma Public Utilities. The Plan consists of potential actions in Puget Sound and other areas in the State of Washington. A specific need exists in the Puget Sound area for balance between east-west transmission capacity and the increasing demand to import power generated east of the Cascades. At certain times of the year, there is more demand for power than the electric system can supply in the Puget Sound area. This high demand, called peak demand, occurs during the winter months when unusually cold weather increases electricity use for heating. The existing power system can supply enough power if no emergencies occur. However, during emergencies, the system will not operate properly. As demand grows, the system becomes more strained. To meet demand, the rate of growth of demand must be reduced or the ability to serve the demand must be increased, or both. The plan to balance Puget Sound's power demand and supply has these purposes: The plan should define a set of actions that would accommodate ten years of load growth (1994--2003). Federal and State environmental quality requirements should be met. The plan should be consistent with the plans of the Northwest Power Planning Council. The plan should serve as a consensus guideline for coordinated utility action. The plan should be flexible to accommodate uncertainties and differing utility needs. The plan should balance environmental impacts and economic costs. The plan should provide electric system reliability consistent with customer expectations. 29 figs., 24 tabs.

  7. Estimated Value of Service Reliability for Electric Utility Customers in the United States

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, M.J.; Mercurio, Matthew; Schellenberg, Josh

    2009-06-01

    Information on the value of reliable electricity service can be used to assess the economic efficiency of investments in generation, transmission and distribution systems, to strategically target investments to customer segments that receive the most benefit from system improvements, and to numerically quantify the risk associated with different operating, planning and investment strategies. This paper summarizes research designed to provide estimates of the value of service reliability for electricity customers in the US. These estimates were obtained by analyzing the results from 28 customer value of service reliability studies conducted by 10 major US electric utilities over the 16 year period from 1989 to 2005. Because these studies used nearly identical interruption cost estimation or willingness-to-pay/accept methods it was possible to integrate their results into a single meta-database describing the value of electric service reliability observed in all of them. Once the datasets from the various studies were combined, a two-part regression model was used to estimate customer damage functions that can be generally applied to calculate customer interruption costs per event by season, time of day, day of week, and geographical regions within the US for industrial, commercial, and residential customers. Estimated interruption costs for different types of customers and of different duration are provided. Finally, additional research and development designed to expand the usefulness of this powerful database and analysis are suggested.

  8. 18 CFR 375.303 - Delegations to the Director of the Office of Electric Reliability.

    Science.gov (United States)

    2010-04-01

    ... Director of the Office of Electric Reliability. 375.303 Section 375.303 Conservation of Power and Water... Delegations § 375.303 Delegations to the Director of the Office of Electric Reliability. The Commission... Electric Reliability Organization or Regional Entity rules or procedures; (ii) Reject an application...

  9. 18 CFR 39.10 - Changes to an Electric Reliability Organization Rule or Regional Entity Rule.

    Science.gov (United States)

    2010-04-01

    ... RULES CONCERNING CERTIFICATION OF THE ELECTRIC RELIABILITY ORGANIZATION; AND PROCEDURES FOR THE ESTABLISHMENT, APPROVAL, AND ENFORCEMENT OF ELECTRIC RELIABILITY STANDARDS § 39.10 Changes to an Electric... Reliability Organization Rule or Regional Entity Rule. 39.10 Section 39.10 Conservation of Power and Water...

  10. Potential for deserts to supply reliable renewable electric power

    Science.gov (United States)

    Labordena, Mercè; Lilliestam, Johan

    2015-04-01

    To avoid dangerous climate change, the electricity systems must be decarbonized by mid-century. The world has sufficient renewable electricity resources for complete power sector decarbonization, but an expansion of renewables poses several challenges for the electricity systems. First, wind and solar PV power are intermittent and supply-controlled, making it difficult to securely integrate this fluctuating generation into the power systems. Consequently, power sources that are both renewable and dispatchable, such as biomass, hydro and concentrating solar power (CSP), are particularly important. Second, renewable power has a low power density and needs vast areas of land, which is problematic both due to cost reasons and due to land-use conflicts, in particular with agriculture. Renewable and dispatchable technologies that can be built in sparsely inhabited regions or on land with low competition with agriculture would therefore be especially valuable; this land-use competition greatly limits the potential for hydro and biomass electricity. Deserts, however, are precisely such low-competition land, and are at the same time the most suited places for CSP generation, but this option would necessitate long transmission lines from remote places in the deserts to the demand centers such as big cities. We therefore study the potential for fleets of CSP plants in the large deserts of the world to produce reliable and reasonable-cost renewable electricity for regions with high and/or rapidly increasing electricity demand and with a desert within or close to its borders. The regions in focus here are the European Union, North Africa and the Middle East, China and Australia. We conduct the analysis in three steps. First, we identify the best solar generation areas in the selected deserts using geographic information systems (GIS), and applying restrictions to minimize impact on biodiversity, soils, human heath, and land-use and land-cover change. Second, we identify

  11. Thermal Management and Reliability of Power Electronics and Electric Machines

    Energy Technology Data Exchange (ETDEWEB)

    Narumanchi, Sreekant

    2016-08-03

    Increasing the number of electric-drive vehicles (EDVs) on America's roads has been identified as a strategy with near-term potential for dramatically decreasing the nation's dependence on oil -- by the U.S. Department of Energy, the federal cross-agency EV-Everywhere Challenge, and the automotive industry. Mass-market deployment will rely on meeting aggressive technical targets, including improved efficiency and reduced size, weight, and cost. Many of these advances will depend on optimization of thermal management. Effective thermal management is critical to improving the performance and ensuring the reliability of EDVs. Efficient heat removal makes higher power densities and lower operating temperatures possible, and in turn enables cost and size reductions. The National Renewable Energy Laboratory (NREL), along with DOE and industry partners is working to develop cost-effective thermal management solutions to increase device and component power densities. In this presentation, the activities in recent years related to thermal management and reliability of automotive power electronics and electric machines will be presented.

  12. Thermal Management and Reliability of Power Electronics and Electric Machines

    Energy Technology Data Exchange (ETDEWEB)

    Narumanchi, Sreekant

    2016-06-13

    Increasing the number of electric-drive vehicles (EDVs) on America's roads has been identified as a strategy with near-term potential for dramatically decreasing the nation's dependence on oil - by the U.S. Department of Energy, the federal cross-agency EV-Everywhere Challenge, and the automotive industry. Mass-market deployment will rely on meeting aggressive technical targets, including improved efficiency and reduced size, weight, and cost. Many of these advances will depend on optimization of thermal management. Effective thermal management is critical to improving the performance and ensuring the reliability of EDVs. Efficient heat removal makes higher power densities and lower operating temperatures possible, and in turn enables cost and size reductions. The National Renewable Energy Laboratory (NREL), along with DOE and industry partners is working to develop cost-effective thermal management solutions to increase device and component power densities. In this presentation, the activities in recent years related to thermal management and reliability of automotive power electronics and electric machines are presented.

  13. Risk management in a competitive electricity market

    International Nuclear Information System (INIS)

    Liu, Min; Wu, Felix F.

    2007-01-01

    In a competitive electricity market, it is necessary and important to develop an appropriate risk management scheme for trade with full utilization of the multi-market environment in order to maximize participants' benefits and minimize the corresponding risks. Based on the analyses to trading environments and risks in the electricity market, a layered framework of risk management for electric energy trading is proposed in this paper. Simulation results confirmed that trading among multiple markets is helpful to reduce the complete risk, and VaR provides a useful approach to judge whether the formed risk-control scheme is acceptable. (author)

  14. Electric Power quality Analysis in research reactor: Impacts on nuclear safety assessment and electrical distribution reliability

    International Nuclear Information System (INIS)

    Touati, Said; Chennai, Salim; Souli, Aissa

    2015-01-01

    The increased requirements on supervision, control, and performance in modern power systems make power quality monitoring a common practise for utilities. Large databases are created and automatic processing of the data is required for fast and effective use of the available information. Aim of the work presented in this paper is the development of tools for analysis of monitoring power quality data and in particular measurements of voltage and currents in various level of electrical power distribution. The study is extended to evaluate the reliability of the electrical system in nuclear plant. Power Quality is a measure of how well a system supports reliable operation of its loads. A power disturbance or event can involve voltage, current, or frequency. Power disturbances can originate in consumer power systems, consumer loads, or the utility. The effect of power quality problems is the loss power supply leading to severe damage to equipments. So, we try to track and improve system reliability. The assessment can be focused on the study of impact of short circuits on the system, harmonics distortion, power factor improvement and effects of transient disturbances on the Electrical System during motor starting and power system fault conditions. We focus also on the review of the Electrical System design against the Nuclear Directorate Safety Assessment principles, including those extended during the last Fukushima nuclear accident. The simplified configuration of the required system can be extended from this simple scheme. To achieve these studies, we have used a demo ETAP power station software for several simulations. (authors)

  15. Electric Power quality Analysis in research reactor: Impacts on nuclear safety assessment and electrical distribution reliability

    Energy Technology Data Exchange (ETDEWEB)

    Touati, Said; Chennai, Salim; Souli, Aissa [Nuclear Research Centre of Birine, Ain Oussera, Djelfa Province (Algeria)

    2015-07-01

    The increased requirements on supervision, control, and performance in modern power systems make power quality monitoring a common practise for utilities. Large databases are created and automatic processing of the data is required for fast and effective use of the available information. Aim of the work presented in this paper is the development of tools for analysis of monitoring power quality data and in particular measurements of voltage and currents in various level of electrical power distribution. The study is extended to evaluate the reliability of the electrical system in nuclear plant. Power Quality is a measure of how well a system supports reliable operation of its loads. A power disturbance or event can involve voltage, current, or frequency. Power disturbances can originate in consumer power systems, consumer loads, or the utility. The effect of power quality problems is the loss power supply leading to severe damage to equipments. So, we try to track and improve system reliability. The assessment can be focused on the study of impact of short circuits on the system, harmonics distortion, power factor improvement and effects of transient disturbances on the Electrical System during motor starting and power system fault conditions. We focus also on the review of the Electrical System design against the Nuclear Directorate Safety Assessment principles, including those extended during the last Fukushima nuclear accident. The simplified configuration of the required system can be extended from this simple scheme. To achieve these studies, we have used a demo ETAP power station software for several simulations. (authors)

  16. Puget Sound Area Electric Reliability Plan : Final Environmental Impact Statement.

    Energy Technology Data Exchange (ETDEWEB)

    United States. Bonneville Power Administration.

    1992-04-01

    A specific need exists in the Puget Sound area for balance between east-west transmission capacity and the increasing demand to import power generated east of the Cascades. At certain times of the year, and during certain conditions, there is more demand for power in the Puget Sound area than the transmission system and existing generation can reliably supply. This high demand, called peak demand occurs during the winter months when unusually cold weather increases electricity use for heating. The existing power system can supply enough power if no emergencies occur. However, during emergencies the system will not operate properly. As demand grows, the system becomes more strained. To meet demand, the rate of growth of demand must be reduced or the ability to serve the demand must be increased, or both.

  17. 10 CFR 500.3 - Electric regions-electric region groupings for reliability measurements under the Powerplant and...

    Science.gov (United States)

    2010-01-01

    ... System (APS)—7, except Duquesne Light Company. 2. American Electric Power System (AEP)—entire AEP System... 10 Energy 4 2010-01-01 2010-01-01 false Electric regions-electric region groupings for reliability... of electric regions for use with regard to the Act. The regions are identified by FERC Power Supply...

  18. Electricity supply. Older plants' impact on reliability and air quality

    International Nuclear Information System (INIS)

    England-Joseph, Judy A.; Adams, Charles M.; Wood, David G.; Feehan, Daniel J.; Veal, Howard F.; Skeen, John H. III; Koenigs, Melvin J.; Lichtenfeld, David I.; Seretakis, Pauline J.

    1990-09-01

    Life extension of fossil fuel plants is a relatively recent phenomenon; thus, utilities have little experience to demonstrate the longer-term operating reliability of plants with an extended service life. While utility industry officials and government and industry studies express optimism that these plants will continue to operate reliably, the officials and the studies also caution that it is too soon to determine how pursuing life extension will affect the reliability of the nation's electricity supply. According to DOE, the number of fossil fuel generating units' 30 years old or older is expected to increase from about 2,500 in 1989 to roughly 3,700 in 1998, increasing such plants' share of overall generating capacity from 13 percent in 1989 to 27 percent in 1998. EPA estimates that with existing air quality requirements, fossil fuel plant emissions will increase steadily during the coming decade. Proposed acid rain control legislation, which would affect many plants that may have their service life extended, would require utilities to significantly reduce emissions by the year 2000 but would allow utilities flexibility in deciding how and where to achieve the reductions. If such legislation is enacted, utilities generally are expected to find reducing emissions from existing plants more cost-effective than replacing them and to continue extending plants' service life. Officials of DOE and utility organizations expressed concern, however, that EPA could decide, as it did for one plant in 1988, that alterations made in extending the service life of plants exempted from the Clean Air Act would result in increased emissions and thus cause the altered plants to lose their exemption. According to the officials, the additional costs of achieving the Clean Air Act's standards could discourage some life extension projects. However, such decisions by EPA could also reduce the nation's total power plant emissions by eliminating an existing incentive to retain exempt

  19. Comparative risk assessment for electricity generation

    International Nuclear Information System (INIS)

    Thoene, E.; Kallenbach, U.

    1988-01-01

    The following conclusions are drawn: There is no 'zero-risk option' in electricity generation. Risk comparison meets with considerable problems relating to available data and methods. Taking into account the existing uncertainties, technology ranking in terms of risks involved cannot be done, but the major risk elements of the various electricity generating systems can be clearly identified. The risks defined cannot be interpreted so as to lead to an abolishment of certain techniques due to risks involved, particularly if one sees the risks from electricity generation in relation to other health hazards. The use of coal for electricity generation clearly ranks top with regard to occupational risks and hazards to public health. (orig./HP) [de

  20. Evaluating North American Electric Grid Reliability Using the Barabasi-Albert Network Model

    OpenAIRE

    Chassin, David P.; Posse, Christian

    2004-01-01

    The reliability of electric transmission systems is examined using a scale-free model of network structure and failure propagation. The topologies of the North American eastern and western electric networks are analyzed to estimate their reliability based on the Barabasi-Albert network model. A commonly used power system reliability index is computed using a simple failure propagation model. The results are compared to the values of power system reliability indices previously obtained using s...

  1. 78 FR 7773 - Notice of Commissioner and Staff Attendance at North American Electric Reliability Corporation...

    Science.gov (United States)

    2013-02-04

    ... Board of Trustees Meetings, Board of Trustees Compliance Committee, Corporate Governance and Human Resources Committee, and Standards Oversight and Technology Committee Meetings. Hotel del Coronado, 1500... Association, Inc. v. Western Electric Coordinating Council and North American Electric Reliability Corporation...

  2. Risk and reliability assessment for telecommunications networks

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-08-01

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

  3. Structural reliability analysis and seismic risk assessment

    International Nuclear Information System (INIS)

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

    1984-01-01

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

  4. Puget Sound area electric reliability plan: Draft Environmental Impact Statement

    International Nuclear Information System (INIS)

    1992-04-01

    The purpose of this appendix to the draft environmental impact statement (EIS) report is to provide an update of the latest study work done on transmission system options for the Puget Sound Area Electric Reliability Plan. Also included in the attachments to the EIS are 2 reports analyzing the voltage stability of the Puget Sound transmission system and a review by Power Technologies, Inc. of the BPA voltage stability analysis and reactive options. Five transmission line options and several reactive options are presently being considered as possible solutions to the PSAFRP by the Transmission Team. The first two line options would be built on new rights-of way adjacent (as much as possible) to existing corridors. The reactive options would optimize the existing transmission system capability by adding new stations for series capacitors and/or switchgear. The other three line options are rebuilds or upgrades of existing cross mountain transmission lines. These options are listed below and include a preliminary assessment of the additional transmission system reinforcement required to integrate the new facilities into the existing transmission system. Plans were designed to provide at least 500 MVAR reactive margin

  5. A framework for reliability and risk centered maintenance

    International Nuclear Information System (INIS)

    Selvik, J.T.; Aven, T.

    2011-01-01

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

  6. Risk analysis of critical infrastructures emphasizing electricity supply and interdependencies

    International Nuclear Information System (INIS)

    Kjølle, G.H.; Utne, I.B.; Gjerde, O.

    2012-01-01

    Failures in critical infrastructures can cause major damage to society. Wide-area interruptions (blackouts) in the electricity supply system have severe impacts on societal critical functions and other critical infrastructures, but there is no agreed-upon framework on how to analyze and predict the reliability of electricity supply. Thus, there is a need for an approach to cross-sector risk analyses, which facilitates risk analysis of outages in the electricity supply system and enables investigation of cascading failures and consequences in other infrastructures. This paper presents such an approach, which includes contingency analysis (power flow) and reliability analysis of power systems, as well as use of a cascade diagram for investigating interdependencies. A case study was carried out together with the Emergency Preparedness Group in the city of Oslo, Norway and the network company Hafslund Nett. The case study results highlight the need for cross-sector analyses by showing that the total estimated societal costs are substantially higher when cascading effects and consequences to other infrastructures are taken into account compared to only considering the costs of electricity interruptions as seen by the network company. The approach is a promising starting point for cross-sector risk analysis of electricity supply interruptions and consequences for dependent infrastructures.

  7. 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...

  8. 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.

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

    NARCIS (Netherlands)

    Wölbert, E.M.; Riedl, A.M.

    2013-01-01

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

  10. 77 FR 13585 - Electricity Subsector Cybersecurity Risk Management Process Guideline

    Science.gov (United States)

    2012-03-07

    ... DEPARTMENT OF ENERGY Electricity Subsector Cybersecurity Risk Management Process Guideline AGENCY... Electricity Subsector Cybersecurity Risk Management Process guideline. The guideline describes a risk... Cybersecurity Risk Management Process Guideline. The primary goal of this guideline is to describe a risk...

  11. Simulation Approach to Mission Risk and Reliability Analysis, Phase I

    Data.gov (United States)

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

  12. Reliability Prediction Approaches For Domestic Intelligent Electric Energy Meter Based on IEC62380

    Science.gov (United States)

    Li, Ning; Tong, Guanghua; Yang, Jincheng; Sun, Guodong; Han, Dongjun; Wang, Guixian

    2018-01-01

    The reliability of intelligent electric energy meter is a crucial issue considering its large calve application and safety of national intelligent grid. This paper developed a procedure of reliability prediction for domestic intelligent electric energy meter according to IEC62380, especially to identify the determination of model parameters combining domestic working conditions. A case study was provided to show the effectiveness and validation.

  13. Bayesian Inference for NASA Probabilistic Risk and Reliability Analysis

    Science.gov (United States)

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

    2009-01-01

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

  14. Reliability Assessment of Wind Farm Electrical System Based on a Probability Transfer Technique

    Directory of Open Access Journals (Sweden)

    Hejun Yang

    2018-03-01

    Full Text Available The electrical system of a wind farm has a significant influence on the wind farm reliability and electrical energy yield. The disconnect switch installed in an electrical system cannot only improve the operating flexibility, but also enhance the reliability for a wind farm. Therefore, this paper develops a probabilistic transfer technique for integrating the electrical topology structure, the isolation operation of disconnect switch, and stochastic failure of electrical equipment into the reliability assessment of wind farm electrical system. Firstly, as the traditional two-state reliability model of electrical equipment cannot consider the isolation operation, so the paper develops a three-state reliability model to replace the two-state model for incorporating the isolation operation. In addition, a proportion apportion technique is presented to evaluate the state probability. Secondly, this paper develops a probabilistic transfer technique based on the thoughts that through transfer the unreliability of electrical system to the energy transmission interruption of wind turbine generators (WTGs. Finally, some novel indices for describing the reliability of wind farm electrical system are designed, and the variance coefficient of the designed indices is used as a convergence criterion to determine the termination of the assessment process. The proposed technique is applied to the reliability assessment of a wind farm with the different topologies. The simulation results show that the proposed techniques are effective in practical applications.

  15. Electric propulsion reliability: Statistical analysis of on-orbit anomalies and comparative analysis of electric versus chemical propulsion failure rates

    Science.gov (United States)

    Saleh, Joseph Homer; Geng, Fan; Ku, Michelle; Walker, Mitchell L. R.

    2017-10-01

    With a few hundred spacecraft launched to date with electric propulsion (EP), it is possible to conduct an epidemiological study of EP's on orbit reliability. The first objective of the present work was to undertake such a study and analyze EP's track record of on orbit anomalies and failures by different covariates. The second objective was to provide a comparative analysis of EP's failure rates with those of chemical propulsion. Satellite operators, manufacturers, and insurers will make reliability- and risk-informed decisions regarding the adoption and promotion of EP on board spacecraft. This work provides evidence-based support for such decisions. After a thorough data collection, 162 EP-equipped satellites launched between January 1997 and December 2015 were included in our dataset for analysis. Several statistical analyses were conducted, at the aggregate level and then with the data stratified by severity of the anomaly, by orbit type, and by EP technology. Mean Time To Anomaly (MTTA) and the distribution of the time to (minor/major) anomaly were investigated, as well as anomaly rates. The important findings in this work include the following: (1) Post-2005, EP's reliability has outperformed that of chemical propulsion; (2) Hall thrusters have robustly outperformed chemical propulsion, and they maintain a small but shrinking reliability advantage over gridded ion engines. Other results were also provided, for example the differentials in MTTA of minor and major anomalies for gridded ion engines and Hall thrusters. It was shown that: (3) Hall thrusters exhibit minor anomalies very early on orbit, which might be indicative of infant anomalies, and thus would benefit from better ground testing and acceptance procedures; (4) Strong evidence exists that EP anomalies (onset and likelihood) and orbit type are dependent, a dependence likely mediated by either the space environment or differences in thrusters duty cycles; (5) Gridded ion thrusters exhibit both

  16. Reliability and Probabilistic Risk Assessment - How They Play Together

    Science.gov (United States)

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

    2015-01-01

    PRA methodology is one of the probabilistic analysis methods that NASA brought from the nuclear industry to assess the risk of LOM, LOV and LOC for launch vehicles. PRA is a system scenario based risk assessment that uses a combination of fault trees, event trees, event sequence diagrams, and probability and statistical data to analyze the risk of a system, a process, or an activity. It is a process designed to answer three basic questions: What can go wrong? How likely is it? What is the severity of the degradation? Since 1986, NASA, along with industry partners, has conducted a number of PRA studies to predict the overall launch vehicles risks. Planning Research Corporation conducted the first of these studies in 1988. In 1995, Science Applications International Corporation (SAIC) conducted a comprehensive PRA study. In July 1996, NASA conducted a two-year study (October 1996 - September 1998) to develop a model that provided the overall Space Shuttle risk and estimates of risk changes due to proposed Space Shuttle upgrades. After the Columbia accident, NASA conducted a PRA on the Shuttle External Tank (ET) foam. This study was the most focused and extensive risk assessment that NASA has conducted in recent years. It used a dynamic, physics-based, integrated system analysis approach to understand the integrated system risk due to ET foam loss in flight. Most recently, a PRA for Ares I launch vehicle has been performed in support of the Constellation program. Reliability, on the other hand, addresses the loss of functions. In a broader sense, reliability engineering is a discipline that involves the application of engineering principles to the design and processing of products, both hardware and software, for meeting product reliability requirements or goals. It is a very broad design-support discipline. It has important interfaces with many other engineering disciplines. Reliability as a figure of merit (i.e. the metric) is the probability that an item will

  17. 78 FR 38851 - Electric Reliability Organization Proposal To Retire Requirements in Reliability Standards

    Science.gov (United States)

    2013-06-28

    ... either: Provide little protection for Bulk-Power System reliability or are redundant with other aspects... for retirement either: (1) Provide little protection for Bulk-Power System reliability or (2) are... to assure reliability of the Bulk-Power System and should be withdrawn. We have identified 41...

  18. Can Slovakia secure reliable electricity supply without nuclear?

    International Nuclear Information System (INIS)

    Pnacek, I.

    2004-01-01

    In this presentation author deals with structure of electricity production in the Slovak republic in 2006 and perspectives of electricity supply up to 2020 year. Decommissioning of Unit 1 and Unit 2 of the Bohunice NPP and completion of Unit 3 and 4 of the Mochovce NPP are discussed

  19. 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.

  20. Plant and control system reliability and risk model

    International Nuclear Information System (INIS)

    Niemelae, I.M.

    1986-01-01

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

  1. Reliable electricity. The effects of system integration and cooperative measures to make it work

    International Nuclear Information System (INIS)

    Hagspiel, Simeon; Koeln Univ.

    2017-01-01

    We investigate the effects of system integration for reliability of supply in regional electricity systems along with cooperative measures to support it. Specifically, we set up a model to contrast the benefits from integration through statistical balancing (i.e., a positive externality) with the risk of cascading outages (a negative externality). The model is calibrated with a comprehensive dataset comprising 28 European countries on a high spatial and temporal resolution. We find that positive externalities from system integration prevail, and that cooperation is key to meet reliability targets efficiently. To enable efficient solutions in a non-marketed environment, we formulate the problem as a cooperative game and study different rules to allocate the positive and negative effects to individual countries. Strikingly, we find that without a mechanism, the integrated solution is unstable. In contrast, proper transfer payments can be found to make all countries better off in full integration, and the Nucleolus is identified as a particularly promising candidate. The rule could be used as a basis for compensation payments to support the successful integration and cooperation of electricity systems.

  2. Reliable electricity. The effects of system integration and cooperative measures to make it work

    Energy Technology Data Exchange (ETDEWEB)

    Hagspiel, Simeon [Koeln Univ. (Germany). Energiewirtschaftliches Inst.; Koeln Univ. (Germany). Dept. of Economics

    2017-12-15

    We investigate the effects of system integration for reliability of supply in regional electricity systems along with cooperative measures to support it. Specifically, we set up a model to contrast the benefits from integration through statistical balancing (i.e., a positive externality) with the risk of cascading outages (a negative externality). The model is calibrated with a comprehensive dataset comprising 28 European countries on a high spatial and temporal resolution. We find that positive externalities from system integration prevail, and that cooperation is key to meet reliability targets efficiently. To enable efficient solutions in a non-marketed environment, we formulate the problem as a cooperative game and study different rules to allocate the positive and negative effects to individual countries. Strikingly, we find that without a mechanism, the integrated solution is unstable. In contrast, proper transfer payments can be found to make all countries better off in full integration, and the Nucleolus is identified as a particularly promising candidate. The rule could be used as a basis for compensation payments to support the successful integration and cooperation of electricity systems.

  3. Bulk electric system reliability evaluation incorporating wind power and demand side management

    Science.gov (United States)

    Huang, Dange

    Electric power systems are experiencing dramatic changes with respect to structure, operation and regulation and are facing increasing pressure due to environmental and societal constraints. Bulk electric system reliability is an important consideration in power system planning, design and operation particularly in the new competitive environment. A wide range of methods have been developed to perform bulk electric system reliability evaluation. Theoretically, sequential Monte Carlo simulation can include all aspects and contingencies in a power system and can be used to produce an informative set of reliability indices. It has become a practical and viable tool for large system reliability assessment technique due to the development of computing power and is used in the studies described in this thesis. The well-being approach used in this research provides the opportunity to integrate an accepted deterministic criterion into a probabilistic framework. This research work includes the investigation of important factors that impact bulk electric system adequacy evaluation and security constrained adequacy assessment using the well-being analysis framework. Load forecast uncertainty is an important consideration in an electrical power system. This research includes load forecast uncertainty considerations in bulk electric system reliability assessment and the effects on system, load point and well-being indices and reliability index probability distributions are examined. There has been increasing worldwide interest in the utilization of wind power as a renewable energy source over the last two decades due to enhanced public awareness of the environment. Increasing penetration of wind power has significant impacts on power system reliability, and security analyses become more uncertain due to the unpredictable nature of wind power. The effects of wind power additions in generating and bulk electric system reliability assessment considering site wind speed

  4. State Electricity Regulatory Policy and Distributed Resources: Distributed Resources and Electric System Reliability

    Energy Technology Data Exchange (ETDEWEB)

    Cowart, R.; Harrington, C.; Moskovitz, D.; Shirley, W.; Weston, F.; Sedano, R.

    2002-10-01

    Designing and implementing credit-based pilot programs for distributed resources distribution is a low-cost, low-risk opportunity to find out how these resources can help defer or avoid costly electric power system (utility grid) distribution upgrades. This report describes implementation options for deaveraged distribution credits and distributed resource development zones. Developing workable programs implementing these policies can dramatically increase the deployment of distributed resources in ways that benefit distributed resource vendors, users, and distribution utilities. This report is one in the State Electricity Regulatory Policy and Distributed Resources series developed under contract to NREL (see Annual Technical Status Report of the Regulatory Assistance Project: September 2000-September 2001, NREL/SR-560-32733). Other titles in this series are: (1) Accommodating Distributed Resources in Wholesale Markets, NREL/SR-560-32497; (2) Distributed Resources and Electric System Re liability, NREL/SR-560-32498; (3) Distribution System Cost Methodologies for Distributed Generation, NREL/SR-560-32500; (4) Distribution System Cost Methodologies for Distributed Generation Appendices, NREL/SR-560-32501.

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

    Directory of Open Access Journals (Sweden)

    Saeed Shahrezaei

    2013-04-01

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

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

    African Journals Online (AJOL)

    Subsequently, Bayesian methodologies are framed in an ampler problem list, based on the definition of an opportune "vector of state" and of a vector describing the system performances, aiming to the definition and the calculation or the estimation of system reliability. The purpose of our work is to establish a useful model ...

  7. Engineering and Design: Reliability Analysis of Navigation Lock and Dam Mechanical and Electrical Equipment

    National Research Council Canada - National Science Library

    Beranek, Dwight

    2001-01-01

    This engineer technical letter (ETL) provides guidance for assessing the reliability of mechanical and electrical systems of navigation locks and dams and for establishing an engineering basis for major rehabilitation investment decisions...

  8. Risk assessment and reliability for low level radioactive waste disposal

    International Nuclear Information System (INIS)

    Gregory, P.O.; Jones, G.A.

    1986-01-01

    The reliability of critical design features at low-level radioactive waste disposal facilities is a major concern in the licensing of these structures. To date, no systematic methodology has been adopted to evaluate the geotechnical reliability of Uranium Mill Tailings Remedial Action (UMTRA) disposal facilities currently being designed and/or constructed. This paper discusses and critiques the deterministic methods currently used to evaluate UMTRA reliability. Because deterministic methods may not be applicable in some cases because of the unusually long design life of UMTRA facilities, it is proposed that a probabilistic risk assessment-based methodology be used as a secondary method to aid in the evaluating of geotechnical reliability of critical items. Similar methodologies have proven successful in evaluating the reliability of a variety of conventional earth structures. In this paper, an ''acceptable'' level of risk for UMTRA facilities is developed, an evaluation method is presented, and two example applications of the proposed methodology are provided for a generic UMTRA disposal facility. The proposed technique is shown to be a simple method which might be used to aid in reliability evaluations on a selective basis. Finally, other possible applications and the limitations of the proposed methodology are discussed

  9. Reliability of blood pressure measurement and cardiovascular risk prediction

    NARCIS (Netherlands)

    van der Hoeven, N.V.

    2016-01-01

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

  10. 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...

  11. Concepts of investment risks and strategies in electricity generation

    International Nuclear Information System (INIS)

    De Joode, J.; Boots, M.G.

    2005-06-01

    This report deals with the specific investment risks in electricity generation and discusses the problems associated with energy investments in general and focus on the additional or changing risks resulting from electricity market liberalisation. The focus is on (1) risks under the control of the electricity company, and on (2) market risks, such as the risk of price changes. Ultimately, some of the approaches and strategies that enable electricity producers to counter or mitigate these risks are discussed

  12. Industrial plant electrical systems: Simplicity, reliability, cost savings, redundancies

    International Nuclear Information System (INIS)

    Silvestri, A.; Tommazzolli, F.; Pavia Univ.

    1992-01-01

    This article represents a compact but complete design and construction manual for industrial plant electrical systems. It is to be used by design engineers having prior knowledge of local power supply routes and voltages and regards principally the optimum choice of internal distribution systems which can be radial or single, double ringed or with various network configurations, and with single or multiple supplies, and many or few redundancies. After giving guidelines on the choosing of these options, the manual deals with problematics relevant to suitable cable sizing. A cost benefit benefit analysis method is suggested for the choice of the number of redundancies. Recommendations are given for the choice of transformers, motorized equipment, switch boards and circuit breakers. Reference is made to Italian electrical safety and building codes

  13. Stratum Electricity Markets: Toward Multi-temporal Distributed Risk Management for Sustainable Electricity Provision

    Science.gov (United States)

    Wu, Zhiyong (Richard)

    Motivated by the overall challenge of ensuring long-term sustainable electricity service, we view this challenge as a long-term decision making problem under uncertainties. We start by recognizing that, independent of the industry organization, the uncertainties are enormous and often exogenous to the energy service providers. They are multi-dimensional and are result of fundamental drivers, ranging from the supply side, through the demand side, to the regulatory and policy sides. The basic contribution of this thesis comes from the recognition that long-term investments for ensuring reliable and stable electricity service critically depend on how these uncertainties are perceived, valued and managed by the different stakeholders within the complex industry organization such as the electric power industry. We explain several reasons why price signals obtained from current short-term electricity markets alone are not sufficient enough for long-term sustainable provision. Some enhancements are presented in the thesis to improve the short-term electricity market price signals to reflect the true cost of operation. New market mechanisms and instruments are needed to facilitate the stakeholders to better deal with long-term risks. The problems of ensuring long-term stable reliable service in the sense of the traditional resource adequacy requirements are revisited in both the restructuring industry and regulated industry. We introduce a so-called Stratum Electricity Market (SEM) design as the basic market mechanism for solving the problem of long-term reliable electricity service through a series of interactive multi-lateral market exchange platforms for risks communication, management and evaluations over various time horizons and by the different groups of stakeholders. In other words, our proposed SEM is a basic IT-enabled framework for the decision making processes by various parties over different time. Because of the uniqueness of electricity as a commodity, the

  14. Electric Power Infrastructure Reliability and Security (EPIRS) Reseach and Development Initiative

    Energy Technology Data Exchange (ETDEWEB)

    Rick Meeker; L. Baldwin; Steinar Dale; Alexander Domijan; Davild Larbalestier; Hui Li; Peter McLaren; Sastry Pamidi; Horatio Rodrigo; Michael Steurer

    2010-03-31

    Power systems have become increasingly complex and face unprecedented challenges posed by population growth, climate change, national security issues, foreign energy dependence and an aging power infrastructure. Increased demand combined with increased economic and environmental constraints is forcing state, regional and national power grids to expand supply without the large safety and stability margins in generation and transmission capacity that have been the rule in the past. Deregulation, distributed generation, natural and man-made catastrophes and other causes serve to further challenge and complicate management of the electric power grid. To meet the challenges of the 21st century while also maintaining system reliability, the electric power grid must effectively integrate new and advanced technologies both in the actual equipment for energy conversion, transfer and use, and in the command, control, and communication systems by which effective and efficient operation of the system is orchestrated - in essence, the 'smart grid'. This evolution calls for advances in development, integration, analysis, and deployment approaches that ultimately seek to take into account, every step of the way, the dynamic behavior of the system, capturing critical effects due to interdependencies and interaction. This approach is necessary to better mitigate the risk of blackouts and other disruptions and to improve the flexibility and capacity of the grid. Building on prior Navy and Department of Energy investments in infrastructure and resources for electric power systems research, testing, modeling, and simulation at the Florida State University (FSU) Center for Advanced Power Systems (CAPS), this project has continued an initiative aimed at assuring reliable and secure grid operation through a more complete understanding and characterization of some of the key technologies that will be important in a modern electric system, while also fulfilling an education and

  15. The integrated North American electricity market : a bi-national model for securing a reliable supply of electricity

    International Nuclear Information System (INIS)

    Egan, T.

    2004-03-01

    The 50 million people who experienced the power blackout on August 14, 2003 in southern Ontario and the U.S. Midwest and Northeast understood how vital electricity is in our day-to-day lives, but they also saw the resiliency of the North American electricity system. More than 65 per cent of the power generation was restored to service within 12 hours and no damage was caused to the generation or transmission facilities. Although the interconnected North American electricity system is among the most reliable in the world, it is threatened by an aging infrastructure, lack of new generation and transmission to meet demand, and growing regulatory pressures. This report suggests that any measures that respond to the threat of ongoing reliability should be bi-national in scope due to the interconnected nature of the system. Currently, the market, regulatory and administrative systems are different in each country. The full engagement and cooperation of both Canada and the United States is important to ensure future cross-border trade and power reliability. The Canadian Electricity Association proposes the following 7 measures: (1) support an open debate on all the supply options available to meet growing power demands, (2) promote bi-national cooperation in the construction of new transmission capacity to ensure a reliable continental electricity system, (3) examine opportunities for bi-national cooperation for investment in advanced transmission technologies and transmission research and development, (4) promote new generation technology and demand-side measures to relieve existing transmission constraints and reduce the need for new transmission facilities, (5) endorse a self-governing international organization for developing and enforcing mandatory reliability standards for the electricity industry, (6) coordinate measures to promote critical infrastructure protection, and (7) harmonize U.S. and Canadian efforts to streamline or clarify regulation of electricity

  16. Predicting risk and human reliability: a new approach

    International Nuclear Information System (INIS)

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

    2009-01-01

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

  17. On-site A.C. electric power sources for 900 MWe French nuclear power reactors: reliability and importance for safety

    Energy Technology Data Exchange (ETDEWEB)

    Milhem, J. L.; Gros, G. [Commissariat a l' Energie Atomique, Institut de Protection et Surete Nucleaire, Departement d' Analyse de Surete, B.P. No. 6, 92260 Fontenay-aux-Roses (France)

    1986-02-15

    After presenting briefly the new provisions laid down by the Electricite de France to meet a total electrical power loss, the main elements of the probabilistic study concerning the corresponding risk described: reliability data of internal sources used, results of risk Improvement brought by the new measures, importance for Internal source before and after Implementation of the new measures. (authors)

  18. On-site A.C. electric power sources for 900 MWe french nuclear power reactors: reliability and importances for safety

    International Nuclear Information System (INIS)

    Milhem, J.L.; Gros, G.

    1985-10-01

    After presenting briefly the new provisions laid down by the Electricite de France to meet a total electrical power loss, the main elements of the probabilistic study concerning the corresponding risk are described: reliability data of internal sources used, results of risk improvement brought by the new measures, importance for internal source before and after implementation of the new measures

  19. Risk management of power supply in open electricity market

    International Nuclear Information System (INIS)

    Rinta-Runsala, E.; Kiviniemi, J.

    1999-12-01

    The open electricity market has increased the need of risk management in electric utilities. In this publication the concepts of risk assessment and measures mostly concentrating on market risks for power supply companies are reported. An essential past of the risk management includes the electricity derivates and trade

  20. Forward reliability markets: Less risk, less market power, more efficiency

    International Nuclear Information System (INIS)

    Cramton, Peter; Stoft, Steven

    2008-01-01

    A forward reliability market is presented. The market coordinates new entry through the forward procurement of reliability options - physical capacity bundled with a financial option to supply energy above a strike price. The market assures adequate generating resources and prices capacity from the bids of competitive new entry in an annual auction. Efficient performance incentives are maintained from a load-following obligation to supply energy above the strike price. The capacity payment fully hedges load from high spot prices, and reduces supplier risk as well. Market power is reduced in the spot market, since suppliers enter the spot market with a nearly balanced position in times of scarcity. Market power in the reliability market is addressed by not allowing existing supply to impact the capacity price. The approach, which has been adopted in New England and Colombia, is readily adapted to either a thermal system or a hydro system. (author)

  1. Reliability of copper based alloys for electric resistance spot welding

    International Nuclear Information System (INIS)

    Jovanovicj, M.; Mihajlovicj, A.; Sherbedzhija, B.

    1977-01-01

    Durability of copper based alloys (B-5 and B-6) for electric resistance spot-welding was examined. The total amount of Be, Ni and Zr was up to 2 and 1 wt.% respectively. Good durability and satisfactory quality of welded spots were obtained in previous laboratory experiments carried out on the fixed spot-welding machine of an industrial type (only B-5 alloy was examined). Electrodes made of both B-5 and B-6 alloy were tested on spot-welding grips and fixed spot-welding machines in Tvornica automobila Sarajevo (TAS). The obtained results suggest that the durability of electrodes made of B-5 and B-6 alloys is more than twice better than of that used in TAS

  2. The Reliability and Predictive Validity of the Stalking Risk Profile.

    Science.gov (United States)

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

    2018-03-01

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

  3. 78 FR 803 - Revisions to Electric Reliability Organization Definition of Bulk Electric System and Rules of...

    Science.gov (United States)

    2013-01-04

    ... Bulk 74. Electric System 1. Inclusion I1 (Transformers) 75. Commission Determination 80. 2. Inclusion... configurations are included in the bulk electric system. Inclusions: I1--Transformers with the primary terminal... bulk electric system. 15. NERC explained that inclusion I1 includes transformers with the primary...

  4. Managing total corporate electricity/energy market risks

    International Nuclear Information System (INIS)

    Henney, A.; Keers, G.

    1998-01-01

    The banking industry has developed a tool kit of very useful value at risk techniques for hedging risk, but these techniques must be adapted to the special complexities of the electricity market. This paper starts with a short history of the use of value-at-risk (VAR) techniques in banking risk management and then examines the specific and, in many instances, complex risk management challenges faced by electric companies from the behavior of prices in electricity markets and from the character of generation and electric retailing risks. The third section describes the main methods for making VAR calculations along with an analysis of their suitability for analyzing the risks of electricity portfolios and the case for using profit at risk and downside risk as measures of risk. The final section draws the threads together and explains how to look at managing total corporate electricity market risk, which is a big step toward managing total corporate energy market risk

  5. Using VIIRS Day/Night Band to Measure Electricity Supply Reliability: Preliminary Results from Maharashtra, India

    Directory of Open Access Journals (Sweden)

    Michael L. Mann

    2016-08-01

    Full Text Available Unreliable electricity supplies are common in developing countries and impose large socio-economic costs, yet precise information on electricity reliability is typically unavailable. This paper presents preliminary results from a machine-learning approach for using satellite imagery of nighttime lights to develop estimates of electricity reliability for western India at a finer spatial scale. We use data from the Visible Infrared Imaging Radiometer Suite (VIIRS onboard the Suomi National Polar Partnership (SNPP satellite together with newly-available data from networked household voltage meters. Our results point to the possibilities of this approach as well as areas for refinement. With currently available training data, we find a limited ability to detect individual outages identified by household-level measurements of electricity voltage. This is likely due to the relatively small number of individual outages observed in our preliminary data. However, we find that the approach can estimate electricity reliability rates for individual locations fairly well, with the predicted versus actual regression yielding an R2 > 0.5. We also find that, despite the after midnight overpass time of the SNPP satellite, the reliability estimates derived are representative of daytime reliability.

  6. Assessing Changes in the Reliability of the U.S. Electric Power System

    Energy Technology Data Exchange (ETDEWEB)

    Larsen, Peter H. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Stanford Univ., CA (United States). Dept. of Physics; LaCommare, Kristina H. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Eto, Joseph H. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Sweeney, James L. [Stanford Univ., CA (United States)

    2015-08-01

    Over the past 15 years, the most well-publicized efforts to assess trends in U.S. electric power system reliability have focused only on a subset of all power interruption events (see, for example, Amin 2008 and Campbell 2012)—namely, only the very largest events, which trigger immediate emergency reporting to federal agencies and industry regulators. Anecdotally, these events are thought by many to represent no more than 10% of the power interruptions experienced annually by electricity consumers. Moreover, a review of these emergency reports has identified shortcomings in relying on these data as reliable sources for assessing trends, even with the reliability events they report (Fisher et al. 2012). Recent work has begun to address these limitations by examining trends in reliability data collected annually by electricity distribution companies (Eto et al. 2012). In principle, all power interruptions experienced by electricity customers, regardless of size, are recorded by the distribution utility. Moreover, distribution utilities have a long history of recording this information, often in response to mandates from state public utility commissions (Eto et al. 2006). Thus, studies that rely on reliability data collected by distribution utilities can, in principle, provide a more complete basis upon which to assess trends or changes in reliability over time.

  7. OPTIMIZATION OF THE RELIABILITY OF AGRICULTURAL CONSUMERS ELECTRICITY DISTRIBUTING AND SUPPLY SYSTEMS

    Directory of Open Access Journals (Sweden)

    Lupushor I.

    2007-12-01

    Full Text Available The problems of the optimization reliability in electrical networks of the different class of voltage have probabilistic nature, they discretely change and depend on the number of factors both definite and indefinite and have importance by selection of electric equipment, graph of development of electrical networks and voltage levels. The definition of the major factors, which have determining significance on their value and speed of their change allow to elaborate methods of their optimization and to elaborate effective methods of their growth limitation in electrical networks with the different class of voltage.

  8. Incorporating reliability evaluation into the uncertainty analysis of electricity market price

    International Nuclear Information System (INIS)

    Kang, Chongqing; Bai, Lichao; Xia, Qing; Jiang, Jianjian; Zhao, Jing

    2005-01-01

    A novel model and algorithm for analyzing the uncertainties in electricity market is proposed in this paper. In this model, bidding decision is formulated as a probabilistic model that takes into account the decision-maker's willingness to bid, risk preferences, the fluctuation of fuel-price, etc. At the same time, generating unit's uncertain output model is considered by its forced outage rate (FOR). Based on the model, the uncertainty of market price is then analyzed. Taking the analytical results into consideration, not only the reliability of the power system can be conventionally analyzed, but also the possible distribution of market prices can be easily obtained. The probability distribution of market prices can be further used to calculate the expected output and the sales income of generating unit in the market. Based on these results, it is also possible to evaluate the risk involved by generating units. A simple system with four generating units is used to illustrate the proposed algorithm. The proposed algorithm and the modeling technique are expected to helpful to the market participants in making their economic decisions

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

    International Nuclear Information System (INIS)

    Bonfietti, Gerson

    2003-01-01

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

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

    Directory of Open Access Journals (Sweden)

    B. Mazzorana

    2009-02-01

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

  11. Reliability of solid-state lighting electrical drivers subjected to WHTOL accelerated aging

    Energy Technology Data Exchange (ETDEWEB)

    Lall, Pradeep; Sakalauku, Peter; Davis, Lynn

    2014-05-27

    An investigation of a solid-state lighting (SSL) luminaire with the focus on the electronic driver which has been exposed to a standard wet hot temperature operating life (WHTOL) of 85% RH and 85°C in order to assess reliability of prolonged exposer to a harsh environment has been conducted. SSL luminaires are beginning introduced as head lamps in some of today's luxury automobiles and may also be fulfilling a variety of important outdoor applications such as overhead street lamps, traffic signals and landscape lighting. SSL luminaires in these environments are almost certain to encounter excessive moisture from humidity and high temperatures for a persistent period of time. The lack of accelerated test methods for LEDs to assess long-term reliability prior to introduction into the marketplace, a need for SSL physics based PHM modeling indicators for assessment and prediction of LED life, as well as the U.S. Department of Energy's R&D roadmap to replace todays lighting with SSL luminaires makes it important to increase the understanding of the reliability of SSL devices, specifically, in harsh environment applications. In this work, a set of SSL electrical drivers were investigated to determine failure mechanisms that occur during prolonged harsh environment applications. Each driver consists of four aluminum electrolytic capacitors (AECs) of three different types and was considered the weakest component inside the SSL electrical driver. The reliability of the electrical driver was assessed by monitoring the change in capacitance and the change in equivalent series resistance for each AEC, as well as monitoring the luminous flux of the SSL luminaire or the output of the electrical driver. The luminous flux of a pristine SSL electrical driver was also monitored in order to detect minute changes in the electrical drivers output and to aid in the investigation of the SSL luminaires reliability. The failure mechanisms of the electrical drivers have been

  12. Reliability Assessment of Offshore Wind Turbines Considering Faults of Electrical / Mechanical Components

    DEFF Research Database (Denmark)

    Kostandyan, Erik; Sørensen, John Dalsgaard

    2013-01-01

    For offshore wind turbines, the cost contribution to Cost of Energy from inspections and Operation & Maintenance can be substantial, and can be expected to increase when wind farms are placed at deeper water depths, further from the coast and in more harsh environments. Estimates of the reliability...... is considered and related to reliability estimation by taking into account faults e.g. due to failure of an electrical component or loss of grid....

  13. Flexibility and reliability in long-term planning exercises dedicated to the electricity sector

    Energy Technology Data Exchange (ETDEWEB)

    Maizi, Nadia; Drouineau, Mathilde; Assoumou, Edi; Mazauric, Vincent

    2010-09-15

    Long-term planning models are useful to build plausible options for future energy systems and must consequently address the technological feasibility and associated cost of these options. This paper focuses on the electricity sector and on problems of flexibility and reliability in power systems in order to improve results provided by long-term planning exercises: flexibility needs are integrated as an additional criterion for new investment decisions and, reliability requirements are assessed through the level of electrical losses they induced and a related cost. These approaches are implemented in a long-term planning model and demonstrated through a study of the Reunion Island.

  14. Multidimensional Risk Management for Underground Electricity Networks

    Directory of Open Access Journals (Sweden)

    Garcez Thalles V.

    2014-08-01

    Full Text Available In the paper we consider an electricity provider company that makes decision on allocating resources on electric network maintenance. The investments decrease malfunction rate of network nodes. An accidental event (explosion, fire, etc. or a malfunctioning on underground system can have various consequences and in different perspectives, such as deaths and injuries of pedestrians, fires in nearby locations, disturbances in the flow of vehicular traffic, loss to the company image, operating and financial losses, etc. For this reason it is necessary to apply an approach of the risk management that considers the multidimensional view of the consequences. Furthermore an analysis of decision making should consider network dependencies between the nodes of the electricity distribution system. In the paper we propose the use of the simulation to assess the network effects (such as the increase of the probability of other accidental event and the occurrence of blackouts of the dependent nodes in the multidimensional risk assessment in electricity grid. The analyzed effects include node overloading due to malfunction of adjacent nodes and blackouts that take place where there is temporarily no path in the grid between the power plant and a node. The simulation results show that network effects have crucial role for decisions in the network maintenance – outcomes of decisions to repair a particular node in the network can have significant influence on performance of other nodes. However, those dependencies are non-linear. The effects of network connectivity (number of connections between nodes on its multidimensional performance assessment depend heavily on the overloading effect level. The simulation results do not depend on network type structure (random or small world – however simulation outcomes for random networks have shown higher variance compared to small-world networks.

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

    Science.gov (United States)

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

    2017-06-01

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

  16. Risk and reliability analyses (LURI) and expert judgement techniques

    International Nuclear Information System (INIS)

    Pyy, P.; Pulkkinen, U.

    1998-01-01

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

  17. Risk-minimisation in electricity markets

    DEFF Research Database (Denmark)

    Tegner, Martin; Ernstsen, Rune Ramsdal; Skajaa, Anders

    2017-01-01

    This paper analyses risk management of fixed price, unspecified consumption contracts in energy markets. We model the joint dynamics of the spot-price and the consumption of electricity, study expected loss minimisation for different loss measures, and derive optimal static hedge strategies based...... on forward contracts. The strategies are implemented empirically and compared to a benchmark strategy widely used by the industry. On 2012–2014 Nordic market data, the suggested hedges significantly outperform the benchmark: The realised cumulative profit-and-losses are greater for almost every single one...

  18. 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.

  19. Factors influencing the reliability of non-electric detonating circuit in underground uranium mines and preventive measures of misfiring

    International Nuclear Information System (INIS)

    Li Qin

    2010-01-01

    Characteristics of non-electric detonating circuit are introduced. The main factors influencing the reliability of non-electric detonating circuit are described. Taking an underground blasting of a uranium mine for example, the reliability of various kinds of detonating network system is calculated using the reliability theory and numerical analysis method. The reasons that cause the misfiring in non-electric detonating circuit system are analyzed, and preventive measures are put forward.(authors)

  20. The development of the Czech Republic electric industry - Reliable, safe and responsible source mix

    Energy Technology Data Exchange (ETDEWEB)

    Vrba, Miroslav; Jez, Jiri; Ptacek, Jiri

    2010-09-15

    The paper focuses on the development of the Czech Republic electric industry in close perspective and the prediction of its expected future in period up to 2030. The goal of the paper is to specify methods and procedures applied within periodic assessment of Czech electric power sector balance outlook for the State authorities. A necessity to respect economic recession and politicization of the issue of power sector development has invoked that these items are added to commonly used procedures. A key criterion is the reliable and safe electricity supply by adequate source mix for acceptable prices and environmental aspects.

  1. 77 FR 30517 - Electricity Subsector Cybersecurity Risk Management Process

    Science.gov (United States)

    2012-05-23

    ... DEPARTMENT OF ENERGY Electricity Subsector Cybersecurity Risk Management Process AGENCY: Office of... Electricity Subsector Cybersecurity Risk Management Process guideline. The guideline describes a risk... Management Process. The primary goal of this guideline is to describe a risk management process that is...

  2. Reliability

    OpenAIRE

    Condon, David; Revelle, William

    2017-01-01

    Separating the signal in a test from the irrelevant noise is a challenge for all measurement. Low test reliability limits test validity, attenuates important relationships, and can lead to regression artifacts. Multiple approaches to the assessment and improvement of reliability are discussed. The advantages and disadvantages of several different approaches to reliability are considered. Practical advice on how to assess reliability using open source software is provided.

  3. Reliable CPS design for mitigating semiconductor and battery aging in electric vehicles

    NARCIS (Netherlands)

    Chang, W.; Proebstl, A.; Goswami, D.; Zamani, M.; Chakraborty, S.

    2015-01-01

    Reliability and performance of cyber-physical systems (CPS) in electric vehicles (EVs) are influenced by three design aspects: (i) controller design, (ii) battery usage, i.e., Battery rate capacity and aging effects, (iii) processor aging of the in-vehicle embedded platform. In this paper, we

  4. 77 FR 59745 - Delegation of Authority Regarding Electric Reliability Organization's Budget, Delegation...

    Science.gov (United States)

    2012-10-01

    ...; Order No. 766] Delegation of Authority Regarding Electric Reliability Organization's Budget, Delegation... rule. SUMMARY: The Commission is issuing this Final Rule to revise its delegations of authority to... delegation agreements, and ERO policies and procedures. DATES: This rule is effective October 1, 2012. FOR...

  5. R&D program benefits estimation: DOE Office of Electricity Delivery and Energy Reliability

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    2006-12-04

    The overall mission of the U.S. Department of Energy’s Office of Electricity Delivery and Energy Reliability (OE) is to lead national efforts to modernize the electric grid, enhance the security and reliability of the energy infrastructure, and facilitate recovery from disruptions to the energy supply. In support of this mission, OE conducts a portfolio of research and development (R&D) activities to advance technologies to enhance electric power delivery. Multiple benefits are anticipated to result from the deployment of these technologies, including higher quality and more reliable power, energy savings, and lower cost electricity. In addition, OE engages State and local government decision-makers and the private sector to address issues related to the reliability and security of the grid, including responding to national emergencies that affect energy delivery. The OE R&D activities are comprised of four R&D lines: High Temperature Superconductivity (HTS), Visualization and Controls (V&C), Energy Storage and Power Electronics (ES&PE), and Distributed Systems Integration (DSI).

  6. 78 FR 26349 - Notice of Commissioner and Staff Attendance at North American Electric Reliability Corporation...

    Science.gov (United States)

    2013-05-06

    ... Standards Oversight and Technology Committee Meetings Sheraton Boston Hotel, 39 Dalton Street, Boston, MA, 02199. May 8 (7:00 a.m.-5:00 p.m.) and May 9 (8:00 a.m.-1:00 p.m.), 2013 Further information regarding... American Electric Reliability Corporation For further information, please contact Jonathan First, 202-502...

  7. Evaluation of conventional electric power generating industry quality assurance and reliability practices

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, R.T.; Lauffenburger, H.A.

    1981-03-01

    The techniques and practices utilized in an allied industry (electric power generation) that might serve as a baseline for formulating Quality Assurance and Reliability (QA and R) procedures for photovoltaic solar energy systems were studied. The study results provide direct near-term input for establishing validation methods as part of the SERI performance criteria and test standards development task.

  8. Reliability of supply in competitive electricity markets: The Nordic electricity Market

    International Nuclear Information System (INIS)

    Singh, Balbir

    2005-12-01

    An overview of the current regulation and performance of the network utilities with respect to the reliability of supply across Europe in general indicates wide variation. On the regional level the situation in the Nordic market is no exception. Can the variation in reliability of supply in Nordic region be explained by differences in regulatory frameworks in the Nordic countries and is it possible to draw any best practice lessons for other countries and regions? The Norwegian regulation and performance with respect to reliability criterion is encouraging, however it must be emphasized that the Norwegian experience with reliability regulation in its current form covers a period of 3 years, a period that is too short to evaluate the Norwegian model. A closer examination of the Norwegian model reveals dynamic trade off in reliability performance, which if permanent may endanger the reliability of supply in the long-run. Last, but not the least important is the criterion that choice of regulation should be based on a careful social cost-benefit analysis of the regulatory model where both cost incurred by the regulatory agencies and the compliance costs incurred by the regulated utilities are included. A preliminary analysis of regulatory agencies in the Nordic market indicates that Norwegian model of network regulation is quite resource incentive. While it is premature to draw conclusions about the national regulatory mechanisms, the Nordic cross border regulation through voluntary arrangements under the auspices of NORDEL provides a good example of an arrangement that is useful when implementation of a formal regulatory regime across different jurisdiction is not possible

  9. Systems Reliability Framework for Surface Water Sustainability and Risk Management

    Science.gov (United States)

    Myers, J. R.; Yeghiazarian, L.

    2016-12-01

    With microbial contamination posing a serious threat to the availability of clean water across the world, it is necessary to develop a framework that evaluates the safety and sustainability of water systems in respect to non-point source fecal microbial contamination. The concept of water safety is closely related to the concept of failure in reliability theory. In water quality problems, the event of failure can be defined as the concentration of microbial contamination exceeding a certain standard for usability of water. It is pertinent in watershed management to know the likelihood of such an event of failure occurring at a particular point in space and time. Microbial fate and transport are driven by environmental processes taking place in complex, multi-component, interdependent environmental systems that are dynamic and spatially heterogeneous, which means these processes and therefore their influences upon microbial transport must be considered stochastic and variable through space and time. A physics-based stochastic model of microbial dynamics is presented that propagates uncertainty using a unique sampling method based on artificial neural networks to produce a correlation between watershed characteristics and spatial-temporal probabilistic patterns of microbial contamination. These results are used to address the question of water safety through several sustainability metrics: reliability, vulnerability, resilience and a composite sustainability index. System reliability is described uniquely though the temporal evolution of risk along watershed points or pathways. Probabilistic resilience describes how long the system is above a certain probability of failure, and the vulnerability metric describes how the temporal evolution of risk changes throughout a hierarchy of failure levels. Additionally our approach allows for the identification of contributions in microbial contamination and uncertainty from specific pathways and sources. We expect that this

  10. Commentary: Risk Management and Reliability Design for Buildings

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-05-28

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

  11. Structural reliability analysis applied to pipeline risk analysis

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-07-01

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

  12. Decision theory, the context for risk and reliability analysis

    International Nuclear Information System (INIS)

    Kaplan, S.

    1985-01-01

    According to this model of the decision process then, the optimum decision is that option having the largest expected utility. This is the fundamental model of a decision situation. It is necessary to remark that in order for the model to represent a real-life decision situation, it must include all the options present in that situation, including, for example, the option of not deciding--which is itself a decision, although usually not the optimum one. Similarly, it should include the option of delaying the decision while the authors gather further information. Both of these options have probabilities, outcomes, impacts, and utilities like any option and should be included explicitly in the decision diagram. The reason for doing a quantitative risk or reliability analysis is always that, somewhere underlying there is a decision to be made. The decision analysis therefore always forms the context for the risk or reliability analysis, and this context shapes the form and language of that analysis. Therefore, they give in this section a brief review of the well-known decision theory diagram

  13. Reliability assessment of competing risks with generalized mixed shock models

    International Nuclear Information System (INIS)

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

    2017-01-01

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

  14. Increasing the reliability of electric energy supply to consumers in ROMAG-PROD Heavy Water Plant

    International Nuclear Information System (INIS)

    Barta, Ioan; Hanes, Marian . E-mail electrica@romag.ro

    2004-01-01

    Full text: This work aims at achieving an analysis of time evolution of the status of electrical installations, their performances and reliability, at describing the refurbishment measures adopted, at assessing the efficiency of these measures and also to suggest solutions for improving the reliability in the electric energy supply of ROMAG-PROD Heavy Water Plant. The analysis started from the original design, the manner the electrical installations were mounted, the technological level of this equipment and gives an evaluation of the deficiencies and the evolution of incidents occurred during the operation period. On the basis of the experience gathered one advances new items for equipment renewing and refurbishment of electric installations which together with the existing ones would ensure an electric energy supply more secure and efficient, leading directly to a more safe and efficient operation of the ROMAG-PROD Heavy Water Plant. In this work the incidents of electric energy nature which occurred are analyzed, the equipment which generated events identified and measures to solve these problems proposed

  15. ASCERTAINMENT OF ELECTRIC-SUPPLY SCHEMES RELIABILITY FOR THE ATOMIC POWER PLANT AUXILIARIES

    Directory of Open Access Journals (Sweden)

    A. L. Starzhinskij

    2015-01-01

    Full Text Available The paper completes ascertainment of electrical-supply scheme reliability for the auxiliaries of a nuclear power plant. Thereat the author considers the system behavior during the block normal operation, carrying out current maintenance, and capital repairs in combination with initiating events. The initiating events for reactors include complete blackout, i.e. the loss of outside power supply (normal and reserve; emergency switching one of the working turbogenerators; momentary dumping the normal rating to the level of auxiliaries with seating the cutout valve of one turbo-generator. The combination of any initiating event with the repairing mode in case of one of the system elements failure should not lead to blackout occurrence of more than one system of the reliable power supply. This requirement rests content with the help of the reliable power supply system self-dependence (electrical and functional and the emergency power-supply operational autonomy (diesel generator and accumulator batteries.The reliability indicators of the power supply system for the nuclear power plant auxiliaries are the conditional probabilities of conjoined blackout of one, two, and three sections of the reliable power supply conditional upon an initiating event emerging and the blackout of one, two, and three reliable power-supply sections under the normal operational mode. Furthermore, they also are the blackout periodicity of one and conjointly two, three, and four sections of normal operation under the block normal operational mode. It is established that the blackout of one bus section of normal operation and one section of reliable power-supply system of the auxiliaries that does not lead to complete blackout of the plant auxiliaries may occur once in three years. The probability of simultaneous power failure of two or three normal-operation sections and of two reliable power-supply sections during the power plant service life is unlikely.

  16. Electricity market pricing, risk hedging and modeling

    Science.gov (United States)

    Cheng, Xu

    In this dissertation, we investigate the pricing, price risk hedging/arbitrage, and simplified system modeling for a centralized LMP-based electricity market. In an LMP-based market model, the full AC power flow model and the DC power flow model are most widely used to represent the transmission system. We investigate the differences of dispatching results, congestion pattern, and LMPs for the two power flow models. An appropriate LMP decomposition scheme to quantify the marginal costs of the congestion and real power losses is critical for the implementation of financial risk hedging markets. However, the traditional LMP decomposition heavily depends on the slack bus selection. In this dissertation we propose a slack-independent scheme to break LMP down into energy, congestion, and marginal loss components by analyzing the actual marginal cost of each bus at the optimal solution point. The physical and economic meanings of the marginal effect at each bus provide accurate price information for both congestion and losses, and thus the slack-dependency of the traditional scheme is eliminated. With electricity priced at the margin instead of the average value, the market operator typically collects more revenue from power sellers than that paid to power buyers. According to the LMP decomposition results, the revenue surplus is then divided into two parts: congestion charge surplus and marginal loss revenue surplus. We apply the LMP decomposition results to the financial tools, such as financial transmission right (FTR) and loss hedging right (LHR), which have been introduced to hedge against price risks associated to congestion and losses, to construct a full price risk hedging portfolio. The two-settlement market structure and the introduction of financial tools inevitably create market manipulation opportunities. We investigate several possible market manipulation behaviors by virtual bidding and propose a market monitor approach to identify and quantify such

  17. 76 FR 57723 - Electricity Sector Cybersecurity Risk Management Process Guideline

    Science.gov (United States)

    2011-09-16

    ... DEPARTMENT OF ENERGY Electricity Sector Cybersecurity Risk Management Process Guideline AGENCY... public comment on DOE's intent to publish the Electricity Sector Cybersecurity Risk Management Process Guideline. The guideline describes a risk management process that is targeted to the specific needs of...

  18. How reliably can climate change and mitigation policy impacts on electric utilities be assessed?

    International Nuclear Information System (INIS)

    Dowlatabadi, H.; Kopp, R.J.; Palmer, K.; De Witt, D.

    1993-01-01

    Numerous mechanisms link climate change and electric utilities. Electricity generation releases radiatively active trace substances (RATS). Significant changes in atmospheric concentration of RATS can lead to a change in regional and global climate regimes. Mitigation action designed to prevent or limit climate change is possible through curbing emissions. Climate change and related mitigation actions impact on electric utilities. Foresight in electric utility planning requires reliable predictions of how the utilities may be affected in the decades ahead. In this paper the impacts of climate change and mitigation policies are noted, and our ability to assess these is reviewed. To this end a suite of models exploring supply and demand questions have been developed. The overall conclusion of the study is that the demand-side uncertainties dominate other unknowns and need to be better characterized and understood. (author)

  19. Reliability measurement for mixed mode failures of 33/11 kilovolt electric power distribution stations.

    Directory of Open Access Journals (Sweden)

    Faris M Alwan

    Full Text Available The reliability of the electrical distribution system is a contemporary research field due to diverse applications of electricity in everyday life and diverse industries. However a few research papers exist in literature. This paper proposes a methodology for assessing the reliability of 33/11 Kilovolt high-power stations based on average time between failures. The objective of this paper is to find the optimal fit for the failure data via time between failures. We determine the parameter estimation for all components of the station. We also estimate the reliability value of each component and the reliability value of the system as a whole. The best fitting distribution for the time between failures is a three parameter Dagum distribution with a scale parameter [Formula: see text] and shape parameters [Formula: see text] and [Formula: see text]. Our analysis reveals that the reliability value decreased by 38.2% in each 30 days. We believe that the current paper is the first to address this issue and its analysis. Thus, the results obtained in this research reflect its originality. We also suggest the practicality of using these results for power systems for both the maintenance of power systems models and preventive maintenance models.

  20. Scoping study on trends in the economic value of electricity reliability to the U.S. economy; TOPICAL

    International Nuclear Information System (INIS)

    Eto, Joseph; Koomey, Jonathan; Lehman, Bryan; Martin, Nathan; Mills, Evan; Webber, Carrie; Worrell, Ernst

    2001-01-01

    During the past three years, working with more than 150 organizations representing public and private stakeholders, EPRI has developed the Electricity Technology Roadmap. The Roadmap identifies several major strategic challenges that must be successfully addressed to ensure a sustainable future in which electricity continues to play an important role in economic growth. Articulation of these anticipated trends and challenges requires a detailed understanding of the role and importance of reliable electricity in different sectors of the economy. This report is intended to contribute to that understanding by analyzing key aspects of trends in the economic value of electricity reliability in the U.S. economy. We first present a review of recent literature on electricity reliability costs. Next, we describe three distinct end-use approaches for tracking trends in reliability needs: (1) an analysis of the electricity-use requirements of office equipment in different commercial sectors; (2) an examination of the use of aggregate statistical indicators of industrial electricity use and economic activity to identify high reliability-requirement customer market segments; and (3) a case study of cleanrooms, which is a cross-cutting market segment known to have high reliability requirements. Finally, we present insurance industry perspectives on electricity reliability as an example of a financial tool for addressing customers' reliability needs

  1. Scoping study on trends in the economic value of electricity reliability to the U.S. economy

    Energy Technology Data Exchange (ETDEWEB)

    Eto, Joseph; Koomey, Jonathan; Lehman, Bryan; Martin, Nathan; Mills, Evan; Webber, Carrie; Worrell, Ernst

    2001-06-01

    During the past three years, working with more than 150 organizations representing public and private stakeholders, EPRI has developed the Electricity Technology Roadmap. The Roadmap identifies several major strategic challenges that must be successfully addressed to ensure a sustainable future in which electricity continues to play an important role in economic growth. Articulation of these anticipated trends and challenges requires a detailed understanding of the role and importance of reliable electricity in different sectors of the economy. This report is intended to contribute to that understanding by analyzing key aspects of trends in the economic value of electricity reliability in the U.S. economy. We first present a review of recent literature on electricity reliability costs. Next, we describe three distinct end-use approaches for tracking trends in reliability needs: (1) an analysis of the electricity-use requirements of office equipment in different commercial sectors; (2) an examination of the use of aggregate statistical indicators of industrial electricity use and economic activity to identify high reliability-requirement customer market segments; and (3) a case study of cleanrooms, which is a cross-cutting market segment known to have high reliability requirements. Finally, we present insurance industry perspectives on electricity reliability as an example of a financial tool for addressing customers' reliability needs.

  2. Thermal Management and Reliability of Automotive Power Electronics and Electric Machines

    Energy Technology Data Exchange (ETDEWEB)

    Narumanchi, Sreekant V [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Bennion, Kevin S [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Cousineau, Justine E [National Renewable Energy Laboratory (NREL), Golden, CO (United States); DeVoto, Douglas J [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Feng, Xuhui [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Kekelia, Bidzina [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Kozak, Joseph P [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Major, Joshua [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Moreno, Gilberto [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Paret, Paul P [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Tomerlin, Jeff J [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2018-02-09

    Low-cost, high-performance thermal management technologies are helping meet aggressive power density, specific power, cost, and reliability targets for power electronics and electric machines. The National Renewable Energy Laboratory is working closely with numerous industry and research partners to help influence development of components that meet aggressive performance and cost targets through development and characterization of cooling technologies, and thermal characterization and improvements of passive stack materials and interfaces. Thermomechanical reliability and lifetime estimation models are important enablers for industry in cost-and time-effective design.

  3. Electric Power Infrastructure Reliability And Security Research And Development Initiative. Final report

    International Nuclear Information System (INIS)

    Dale, S.; Meeker, R.; Steurer, M.; Li, H.; Pamidi, S.; Rodrigo, H.; Suryanarayanan, S.; Cartes, D.; Ordonez, J.; Domijan, A.; Liu, W.; Cox, D.; McLaren, P.; Hovsapian, R.; Edwards, D.; Simmons, S.; Wilde, N.; Woodruff, S.; Kopriva, D.; Hussaini, Y.; Mohammed, O.; Zheng, J.; Baldwin, T.L.

    2008-01-01

    This is the final scientific/technical report for the Electric Power Infrastructure Reliability and Security R and D Initiative sponsored by the U.S. Department of Energy, Office of Electricity Delivery and Energy Reliability, under award number DE-FG02-05CH11292. This report covers results from the FSU-led, multi-institution effort conducted over the period 8/15/05 to 10/14/2007. Building upon existing infrastructure for power systems research, modeling, and simulation, the Center for Advanced Power Systems (CAPS) at Florida State University (FSU) is developing world-class programs in electric power systems research and education to support future electric power system needs and challenges. With U.S. Department of Energy Support, FSU CAPS has engaged in a multi-faceted effort to conduct basic and applied research towards understanding, developing, and deploying technologies and approaches that can lead to improved reliability and security of the North American electric power generation and delivery infrastructure. This wide-reaching project, through a number of carefully selected thrusts cutting across several research disciplines, set out to address key terrestrial electric utility power system issues and challenges. The challenges and the thrusts to address them were arrived at through analysis of a number of national reports and recommendations combined with input from an experienced multi-disciplined team of power systems research staff and faculty at FSU CAPS. The resulting project effort can be grouped into four major areas: - Power Systems and New Technology Insertion - Controls, Protection, and Security - Simulation Development - High Temperature Superconductivity (HTS)

  4. Bilateral electric energy contracts: return and risk

    Energy Technology Data Exchange (ETDEWEB)

    Gunn, Laura K.; Silva, Elisa B.; Correia, Paulo B. [State University of Campinas (UNICAMP), SP (Brazil). College of Mechanical Engineering

    2009-07-01

    In Brazil electricity is traded through three segments: the spot market that balances offer and demand, with prices calculated by a cost-based computational model; the regulated market , where prices are settled in public auctions, and the free market for bilateral contracts. As spot and regulated market prices are public information, a seller is able to calculate his opportunity price to trade a bilateral contract in the free market by using the non-arbitrage principle. Thus, the seller searches the price of a bilateral contract in the free market that balances his/her revenues with the value expected in case it were negotiated in the regulated and the spot market. Besides the expected revenue, the seller may also consider the CVaR to measure the risk of her/his bilateral contract in the free market. So this paper develops a binomial lattice approach to price bilateral contracts in the free market, considering the seller's opportunity of negotiations in both regulated and spot markets, and measuring the contract risk directly. (author)

  5. On reliability and maintenance modelling of ageing equipment in electric power systems

    International Nuclear Information System (INIS)

    Lindquist, Tommie

    2008-04-01

    Maintenance optimisation is essential to achieve cost-efficiency, availability and reliability of supply in electric power systems. The process of maintenance optimisation requires information about the costs of preventive and corrective maintenance, as well as the costs of failures borne by both electricity suppliers and customers. To calculate expected costs, information is needed about equipment reliability characteristics and the way in which maintenance affects equipment reliability. The aim of this Ph.D. work has been to develop equipment reliability models taking the effect of maintenance into account. The research has focussed on the interrelated areas of condition estimation, reliability modelling and maintenance modelling, which have been investigated in a number of case studies. In the area of condition estimation two methods to quantitatively estimate the condition of disconnector contacts have been developed, which utilise results from infrared thermography inspections and contact resistance measurements. The accuracy of these methods were investigated in two case studies. Reliability models have been developed and implemented for SF6 circuit-breakers, disconnector contacts and XLPE cables in three separate case studies. These models were formulated using both empirical and physical modelling approaches. To improve confidence in such models a Bayesian statistical method incorporating information from the equipment design process was also developed. This method was illustrated in a case study of SF6 circuit-breaker operating rods. Methods for quantifying the effect of maintenance on equipment condition and reliability have been investigated in case studies on disconnector contacts and SF6 circuit-breakers. The input required by these methods are condition measurements and historical failure and maintenance data, respectively. This research has demonstrated that the effect of maintenance on power system equipment may be quantified using available data

  6. Natural-gas-powered thermoelectricity as a reliability factor in the Brazilian electric sector

    International Nuclear Information System (INIS)

    Fernandes, E.; Oliveira, J.C.S. de; de Oliveira, P.R.; Alonso, P.S.R.

    2008-01-01

    The introduction of natural-gas-powered thermoelectricity into the Brazilian generation sector can be considered as a very complex energy, economic, regulatory and institutional revision. Brazil is a country with very specific characteristics in electricity generation, as approximately 80% of the generating capacity is based on hydroelectricity, showing strong dependency on rain and management of water reservoirs. A low rate of investment in the Brazilian Electricity Industry in the period of 1995-2000, associated with periods of low rainfall, led to a dramatic lowering of the water stocks in the reservoirs. With this scenario and the growing supply of natural gas, both from within Brazil and imported, natural gas thermal electric plants became a good option to diversify the electrical supply system. In spite of the Brazilian Government's efforts to install such plants, the country was faced with severe electricity rationing in 2001. The objective of this work is to show the need to continue with the implementation of natural gas thermal electricity projects, in a manner that allows flexibility and guarantees greater working reliability for the entire Brazilian electricity sector. Taking into account the world trend towards renewable energy, the perspectives of usage of biofuels in the Brazilian Energy Matrix and in electrical energy generation are also analyzed. The very issue of electrical power efficiency in Brazil and its challenges and strategic proposals from the standpoint of Government Programs and results provided so far are presented. The technological constraints in order to put on stream the thermal electric plants are also analyzed. The article concludes with a positive perspective of the usage of natural gas as to be the third pillar in the Brazilian Energy Matrix for the years to come

  7. THE ANALYSIS OF STRUCTURAL RELIABILITY OF THE MAIN ELECTRIC CONNECTION CIRCUITS OF NUCLEAR POWER PLANTS

    Directory of Open Access Journals (Sweden)

    M. A. Korotkevich

    2017-01-01

    Full Text Available The reliability of the main circuit of electrical connections at a nuclear electric power plant that has two units with a capacity of 1,200 MW each has been determined. Reliability, economical, maneuverable properties of the atomic power plant under study are largely determined by its main circuit, so the choice of the circuit for the design and its status in the process of operation occur to be critical objectives. Main electrical connection circuits in nuclear electric power plants are selected on the basis of the schematic networks of the energy system and the land attached to the plant. The circuit of the connection of a nuclear power plant to the grid in the original normal operating modes at all stages of the construction of such a plant should provide the outcome of the full added capacity of a nuclear power plant and the preservation of its stability in the power system without the influence of the emergency system automatics when any outgoing transmission line is disabled. When selecting the main circuit the individual capacity of the installed units and their number are taken into account as well as the order of development of the plant and power supply system; the voltage on which the power of a plant is delivered; a shortcircuit current for switchgear high voltage and the need for their limitation by circuit means; the most power that can be lost when damage to any switch. A model of reliability of the main circuit of electrical connections is designed to detect all types of accidents that are possible at the coincidence of failures of elements with the repair and operational modes that differs in composition and damageability of the equipment, as well as under conditions of the development of accidents due to failure of operation of devices of relay protection and automation.

  8. Electrical system design and reliability at Ontario Hydro nuclear generating stations

    Energy Technology Data Exchange (ETDEWEB)

    Royce, C. J. [Ontario Hydro, 700 University Avenue, Toronto, Ontario M5G 1X6 (Canada)

    1986-02-15

    This paper provides an overview of design practice and the predicted and actual reliability of electrical station service Systems at Ontario Nuclear Generating Stations. Operational experience and licensing changes have indicated the desirability of improving reliability in certain instances. For example, the requirement to start large emergency coolant injection pumps resulted in the turbine generator units in a multi-unit station being used as a back-up power supply. Results of reliability analyses are discussed. To mitigate the effects of common mode events Ontario Hydro adopted a 'two group' approach to the design of safety related Systems. This 'two group' approach is reviewed and a single fully environmentally qualified standby power supply is proposed for future use. (author)

  9. Risk and investment management in liberalized electricity markets

    DEFF Research Database (Denmark)

    Lemming, Jacob Kjærgaard

    2005-01-01

    markets affects the nancial risk related to different decision problems within the areas of risk management and investments in liberalized electricity markets. Focus is on applied microeconomics and analyzes of the interplay between market design parameters and the technical characteristics...... of the electricity system. Theory, literature and introduction to speci c problem areas related to risk management and investments is provided in two separate introductory chapters. Contributions to research within specific problems areas is then subsequently provided by five research papers. The two topics...... are relatively broad, however the two chapters and ve papers all share analyzes of nancial risk in liberalized electricity markets as a common underlying theme. The risk management part of the thesis focusses on modelling and measurement of financial risk in electricity markets. Key topics are electricity price...

  10. Reliability constrained generation expansion planning with consideration of wind farms uncertainties in deregulated electricity market

    International Nuclear Information System (INIS)

    Hemmati, Reza; Hooshmand, Rahmat-Allah; Khodabakhshian, Amin

    2013-01-01

    Highlights: • Generation expansion planning is presented in deregulated electricity market. • Wind farm uncertainty is modeled in the problem. • The profit of each GENCO is maximized and also the safe operation of system is satisfied. • Salve sector is managed as an optimization programming and solved by using PSO technique. • Master sector is considered in pool market and Cournot model is used to simulate it. - Abstract: This paper addresses reliability constrained generation expansion planning (GEP) in the presence of wind farm uncertainty in deregulated electricity market. The proposed GEP aims at maximizing the expected profit of all generation companies (GENCOs), while considering security and reliability constraints such as reserve margin and loss of load expectation (LOLE). Wind farm uncertainty is also considered in the planning and GENCOs denote their planning in the presence of wind farm uncertainty. The uncertainty is modeled by probability distribution function (PDF) and Monte-Carlo simulation (MCS) is used to insert uncertainty into the problem. The proposed GEP is a constrained, nonlinear, mixed-integer optimization programming and solved by using particle swarm optimization (PSO) method. In this paper, Electricity market structure is modeled as a pool market. Simulation results verify the effectiveness and validity of the proposed planning for maximizing GENCOs profit in the presence of wind farms uncertainties in electricity market

  11. The Challenge Posed by Geomagnetic Activity to Electric Power Reliability: Evidence From England and Wales

    Science.gov (United States)

    Forbes, Kevin F.; St. Cyr, O. C.

    2017-10-01

    This paper addresses whether geomagnetic activity challenged the reliability of the electric power system during part of the declining phase of solar cycle 23. Operations by National Grid in England and Wales are examined over the period of 11 March 2003 through 31 March 2005. This paper examines the relationship between measures of geomagnetic activity and a metric of challenged electric power reliability known as the net imbalance volume (NIV). Measured in megawatt hours, NIV represents the sum of all energy deployments initiated by the system operator to balance the electric power system. The relationship between geomagnetic activity and NIV is assessed using a multivariate econometric model. The model was estimated using half-hour settlement data over the period of 11 March 2003 through 31 December 2004. The results indicate that geomagnetic activity had a demonstrable effect on NIV over the sample period. Based on the parameter estimates, out-of-sample predictions of NIV were generated for each half hour over the period of 1 January to 31 March 2005. Consistent with the existence of a causal relationship between geomagnetic activity and the electricity market imbalance, the root-mean-square error of the out-of-sample predictions of NIV is smaller; that is, the predictions are more accurate, when the statistically significant estimated effects of geomagnetic activity are included as drivers in the predictions.

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

    International Nuclear Information System (INIS)

    Lofgren, E.V.

    1985-08-01

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

  13. Reliability and risk analysis data base development: an historical perspective

    International Nuclear Information System (INIS)

    Fragola, Joseph R.

    1996-01-01

    Collection of empirical data and data base development for use in the prediction of the probability of future events has a long history. Dating back at least to the 17th century, safe passage events and mortality events were collected and analyzed to uncover prospective underlying classes and associated class attributes. Tabulations of these developed classes and associated attributes formed the underwriting basis for the fledgling insurance industry. Much earlier, master masons and architects used design rules of thumb to capture the experience of the ages and thereby produce structures of incredible longevity and reliability (Antona, E., Fragola, J. and Galvagni, R. Risk based decision analysis in design. Fourth SRA Europe Conference Proceedings, Rome, Italy, 18-20 October 1993). These rules served so well in producing robust designs that it was not until almost the 19th century that the analysis (Charlton, T.M., A History Of Theory Of Structures In The 19th Century, Cambridge University Press, Cambridge, UK, 1982) of masonry voussoir arches, begun by Galileo some two centuries earlier (Galilei, G. Discorsi e dimostrazioni mathematiche intorno a due nuove science, (Discourses and mathematical demonstrations concerning two new sciences, Leiden, The Netherlands, 1638), was placed on a sound scientific basis. Still, with the introduction of new materials (such as wrought iron and steel) and the lack of theoretical knowledge and computational facilities, approximate methods of structural design abounded well into the second half of the 20th century. To this day structural designers account for material variations and gaps in theoretical knowledge by employing factors of safety (Benvenuto, E., An Introduction to the History of Structural Mechanics, Part II: Vaulted Structures and Elastic Systems, Springer-Verlag, NY, 1991) or codes of practice (ASME Boiler and Pressure Vessel Code, ASME, New York) originally developed in the 19th century (Antona, E., Fragola, J. and

  14. 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

  15. Drought and Heat Wave Impacts on Electricity Grid Reliability in Illinois

    Science.gov (United States)

    Stillwell, A. S.; Lubega, W. N.

    2016-12-01

    A large proportion of thermal power plants in the United States use cooling systems that discharge large volumes of heated water into rivers and cooling ponds. To minimize thermal pollution from these discharges, restrictions are placed on temperatures at the edge of defined mixing zones in the receiving waters. However, during extended hydrological droughts and heat waves, power plants are often granted thermal variances permitting them to exceed these temperature restrictions. These thermal variances are often deemed necessary for maintaining electricity reliability, particularly as heat waves cause increased electricity demand. Current practice, however, lacks tools for the development of grid-scale operational policies specifying generator output levels that ensure reliable electricity supply while minimizing thermal variances. Such policies must take into consideration characteristics of individual power plants, topology and characteristics of the electricity grid, and locations of power plants within the river basin. In this work, we develop a methodology for the development of these operational policies that captures necessary factors. We develop optimal rules for different hydrological and meteorological conditions, serving as rule curves for thermal power plants. The rules are conditioned on leading modes of the ambient hydrological and meteorological conditions at the different power plant locations, as the locations are geographically close and hydrologically connected. Heat dissipation in the rivers and cooling ponds is modeled using the equilibrium temperature concept. Optimal rules are determined through a Monte Carlo sampling optimization framework. The methodology is applied to a case study of eight power plants in Illinois that were granted thermal variances in the summer of 2012, with a representative electricity grid model used in place of the actual electricity grid.

  16. Configuration of risk monitor system by plant defense-in-depth risk monitor and reliability monitor

    International Nuclear Information System (INIS)

    Yoshikawa, Hidekazu; Lind Morten; Yang Ming; Hashim Muhammad; Zhang Zhijian

    2012-01-01

    A new method of risk monitor system of a nuclear power plant has been proposed from the aspect by what degree of safety functions incorporated in the plant system is maintained by multiple barriers of defense-in-depth (DiD). Wherein, the central idea is plant DiD risk monitor and reliability monitor derived from the five aspects of (1) design principle of nuclear safety based on DiD concept, (2) definition of risk and risk to be monitored, (3) severe accident phenomena as major risk, (4) scheme of risk ranking, and (5) dynamic risk display. In this paper, the overall frame of the proposed risk monitor system is summarized and the detailed discussion is made on major items such as definition of risk and risk ranking, anatomy of fault occurrence, two-layer configuration of risk monitor, how to configure individual elements of plant DiD risk monitor, and lastly how to apply for a PWR safety system. (author)

  17. Human Reliability Analysis in Support of Risk Assessment for Positive Train Control

    Science.gov (United States)

    2003-06-01

    This report describes an approach to evaluating the reliability of human actions that are modeled in a probabilistic risk assessment : (PRA) of train control operations. This approach to human reliability analysis (HRA) has been applied in the case o...

  18. Reliability through markets in Ontario : submission by the Independent Electricity Market Operator to the Minister of Energy's Consultation Process

    International Nuclear Information System (INIS)

    2003-01-01

    For the past five years, Ontario has invested $1 billion to restructure and open its electricity market to competition. In recent months, and in response to residential consumers pricing concerns, the Independent Electricity Market Operator (IMO) transferred credits to local distribution companies allowing them to issue $75 rebates to all affected customers as of December 1, 2002, and to bill low-volume and other designated customers at a rate of 4.3 cents per kilowatt hour for the commodity portion of their bills. This report addresses the concern that price responsiveness will be lost for those parts of the market with fixed prices. It was noted that the reliability of the power system could be placed at risk if the range of customers with fixed prices is broadened. Fixed prices would also jeopardize the province's ability to attract new supply and enhance competition in the electricity sector. The IMO believes that price responsiveness in the wholesale market is crucial to the reliability of the electricity system and recommends that a plan for any additional fixed pricing should include a clearly defined phase-out over the period ending in 2006 as new supply comes on-line. The IMO emphasizes that the lack of price responsiveness to the market, particularly in peak energy demand periods, is equivalent to adding hundreds of MW to the load. The report presents lessons learned in other jurisdictions and highlights noteworthy considerations such as the market power mitigation agreement, improving competition, a phased-in approach, and demand side initiatives

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

    International Nuclear Information System (INIS)

    1987-01-01

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

  20. Electricity markets volatility: estimates, regularities and risk management applications

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Masao [Sauder School of Business, University of British Columbia, 2053 Main Mall, Vancouver, BC, V6 T 1Z2 (Canada)]. E-mail: masao.nakamura@sauder.ubc.ca; Nakashima, Tomoaki [Powerex Corp., Vancouver, BC, V6C 2X8 (Canada); Niimura, Takahide [TNC Systems Technologies, Burnaby, BC, V5 H 2W4 (Canada)

    2006-09-15

    The recent deregulation of the market for electric power in many parts of the US and Canada has expanded the set of potential tools for managing the types of risks faced by both generators and consumers of electric power. In particular manufacturing and other firms whose operations are powered by electricity now face, on a continuing basis, the engineering management decisions concerning whether they should buy or produce electricity, and if they are to buy or sell electricity, what types of contracts are optimum. These types of risk management decisions typically involve futures, forwards, options and other financial derivatives. The price and volatility of electric power are known to play an essential role in determining which of these instruments should be used. However, electricity as a commodity possesses certain special features not shared by other commodities and hence its risk properties are not yet well understood. In this paper we consider and test certain hypotheses about the properties of electricity price using recent market data. We find that electricity prices possess certain volatility and other systematic properties that can be characterized by the type and method of delivery of electricity. These properties can be used by firms in formulating their optimal demand and supply schedules of electric power.

  1. Electricity markets volatility: estimates, regularities and risk management applications

    International Nuclear Information System (INIS)

    Nakamura, Masao; Nakashima, Tomoaki; Niimura, Takahide

    2006-01-01

    The recent deregulation of the market for electric power in many parts of the US and Canada has expanded the set of potential tools for managing the types of risks faced by both generators and consumers of electric power. In particular manufacturing and other firms whose operations are powered by electricity now face, on a continuing basis, the engineering management decisions concerning whether they should buy or produce electricity, and if they are to buy or sell electricity, what types of contracts are optimum. These types of risk management decisions typically involve futures, forwards, options and other financial derivatives. The price and volatility of electric power are known to play an essential role in determining which of these instruments should be used. However, electricity as a commodity possesses certain special features not shared by other commodities and hence its risk properties are not yet well understood. In this paper we consider and test certain hypotheses about the properties of electricity price using recent market data. We find that electricity prices possess certain volatility and other systematic properties that can be characterized by the type and method of delivery of electricity. These properties can be used by firms in formulating their optimal demand and supply schedules of electric power

  2. 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

  3. Coal-Powered Electric Generating Unit Efficiency and Reliability Dialogue: Summary Report

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, Emmanuel [Energetics, Inc., Columbia, MD (United States)

    2018-02-01

    Coal continues to play a critical role in powering the Nation’s electricity generation, especially for baseload power plants. With aging coal generation assets facing decreased performance due to the state of the equipment, and with challenges exacerbated by the current market pressures on the coal sector, there are opportunities to advance early-stage technologies that can retrofit or replace equipment components. These changes will eventually result in significant improvements in plant performance once further developed and deployed by industry. Research and development in areas such as materials, fluid dynamics, fuel properties and preparation characteristics, and a new generation of plant controls can lead to new components and systems that can help improve the efficiency and reliability of coal-fired power plants significantly, allowing these assets to continue to provide baseload power. Coal stockpiles at electricity generation plants are typically large enough to provide 30 to 60 days of power prior to resupply—significantly enhancing the stability and reliability of the U.S. electricity sector. Falling prices for non-dispatchable renewable energy and mounting environmental regulations, among other factors, have stimulated efforts to improve the efficiency of these coal-fired electric generating units (EGUs). In addition, increased reliance on natural gas and non-dispatchable energy sources has spurred efforts to further increase the reliability of coal EGUs. The Coal Powered EGU Efficiency and Reliability Dialogue brought together stakeholders from across the coal EGU industry to discuss methods for improvement. Participants at the event reviewed performance-enhancing innovations in coal EGUs, discussed the potential for data-driven management practices to increase efficiency and reliability, investigated the impacts of regulatory compliance on coal EGU performance, and discussed upcoming challenges for the coal industry. This report documents the key

  4. Risk-based Optimization and Reliability Levels of Coastal Structures

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Burcharth, H. F.

    Identification of optimum reliability levels for coastal structures is considered. A class of breakwaters is considered where no human injuries can be expected in cases of failure. The optimum reliability level is identified by minimizing the total costs over the service life of the structure, in...... on the minimumcost reliability levels is investigated for different values of the real rate of interest, the service lifetime, the downtime costs due to malfunction and the decommission costs.......Identification of optimum reliability levels for coastal structures is considered. A class of breakwaters is considered where no human injuries can be expected in cases of failure. The optimum reliability level is identified by minimizing the total costs over the service life of the structure...

  5. Risk-based Optimization and Reliability Levels of Coastal Structures

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Burcharth, Hans F.

    2005-01-01

     Identification of optimum reliability levels for coastal structures is considered. A class of breakwaters is considered where no human injuries can be expected in cases of failure. The optimum reliability level is identified by minimizing the total costs over the service life of the structure, i...... on the minimumcost reliability levels is investigated for different values of the real rate of interest, the service lifetime, the downtime costs due to malfunction and the decommission costs....... Identification of optimum reliability levels for coastal structures is considered. A class of breakwaters is considered where no human injuries can be expected in cases of failure. The optimum reliability level is identified by minimizing the total costs over the service life of the structure...

  6. Demand participation in the restructured Electric Reliability Council of Texas market

    International Nuclear Information System (INIS)

    Zarnikau, Jay W.

    2010-01-01

    Does an electricity market which has been restructured to foster competition provide greater opportunities for demand response than a traditional regulated utility industry? The experiences of the restructured Electric Reliability Council of Texas (ERCOT) market over the past eight years provide some hope that it is possible to design a competitive market which will properly value and accommodate demand response. While the overall level of demand response in ERCOT is below the levels enjoyed prior to restructuring, there have nonetheless been some promising advances, including the integration of demand-side resources into competitive markets for ancillary services. ERCOT's experiences demonstrate that the degree of demand participation in a restructured market is highly sensitive to the market design. But even in a market which has been deregulated to a large degree, regulatory intervention and special demand-side programs may be needed in order to bolster demand response. (author)

  7. Hybrid instrument applied to human reliability study in event of loss of external electric power in a nuclear power plant

    International Nuclear Information System (INIS)

    Martins, Eduardo Ferraz

    2015-01-01

    The study projects in highly complex installations involves robust modeling, supported by conceptual and mathematical tools, to carry out systematic research and structured the different risk scenarios that can lead to unwanted events from occurring equipment failures or human errors. In the context of classical modeling, the Probabilistic Safety Analysis (PSA) seeks to provide qualitative and quantitative information about the project particularity and their operational facilities, including the identification of factors or scenarios that contribute to the risk and consequent comparison options for increasing safety. In this context, the aim of the thesis is to develop a hybrid instrument (CPP-HI) innovative, from the integrated modeling techniques of Failure Mode and Effect Analysis (FMEA), concepts of Human Reliability Analysis and Probabilistic Composition of Preferences (PCP). In support of modeling and validation of the CPP-HI, a simulation was performed on a triggering event 'Loss of External Electric Power' - PEEE, in a Nuclear Power plant. The results were simulated in a virtual environment (sensitivity analysis) and are robust to the study of Human Reliability Analysis (HRA) in the context of the PSA. (author)

  8. Risk Based Maintenance in Electricity Network Organisations

    NARCIS (Netherlands)

    Mehairjan, R.P.Y.

    2016-01-01

    Presently, maintenance management of assets in infrastructure utilities such as electricity, gas and water are widely undergoing changes towards new working environments. These are mainly driven against the background of stringent regulatory regimes, an ageing asset base, increased customer demands

  9. The role of risk in electricity resource planning

    International Nuclear Information System (INIS)

    Nicodemus, Gerd

    1998-01-01

    Sources of risk in electricity resource planning include: liberalisation electricity markets and environmental effects of energy choice. Market liberalisation favours more flexible, efficient options, risk-adjusted discount rates will account for different project risks, regulation shifts to incentive-based rather than direct control. Choice of social discount rate takes degree of environmental irreversibility into account (time period affected by economic activity) to preserve flexibility; 'public good' character of environmental risk requires lowering the discount rate. Elaborated risk-management policies are helpful in identifying cost-effective energy options

  10. Electricity market design and risk management

    International Nuclear Information System (INIS)

    Boschi, Federico; Cervigni, Guido

    2005-01-01

    We show that each wholesale electricity market design trades-off between efficiency and liquidity. Efficiency requires that the product traded in the wholesale market closely reflect the physical features of electricity. Liquidity requires standardization of the products that ore traded on the wholesale market. We stress that Iiquidity comes at a cost since an excessive degree of standardization may lead to significant inefficiencies and forge wealth transfers among market participants [it

  11. METHODS OF IMPROVING THE RELIABILITY OF THE CONTROL SYSTEM TRACTION POWER SUPPLY OF ELECTRIC TRANSPORT BASED ON AN EXPERT INFORMATION

    Directory of Open Access Journals (Sweden)

    O. O. Matusevych

    2009-03-01

    Full Text Available The author proposed the numerous methods of solving the multi-criterion task – increasing of reliability of control system on the basis of expert information. The information, which allows choosing thoughtfully the method of reliability increasing for a control system of electric transport, is considered.

  12. Reliability and Probabilistic Risk Assessment - How They Play Together

    Science.gov (United States)

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

    2015-01-01

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

  13. Anticipating Interruptions. Security and risk in a liberalized electricity infrastructure

    Energy Technology Data Exchange (ETDEWEB)

    Silvast, A.

    2013-11-01

    During the past ten years, a number of social scientists have emphasized the importance of material infrastructures like electricity supply as a research topic for the social sciences. The developing of such new perspectives concerning infrastructures also includes uncertainties and risks. This research analyzes the management of uncertainties in the Finnish electricity infrastructure by posing the following research question: how are electricity interruptions, or blackouts, anticipated in Finland and how are these interruptions managed as risks? The main research methodology of the work is multi-sited field work. The empirical materials include interviews with experts and lay people (33 interviews); participant observation in two electricity control rooms; an electricity consumer survey (115 respondents); and also a number of infrastructure and security policy documents and observations from electricity security seminars. The materials were primarily gathered between 2004 and 2008. Social science research often links risks with major current social changes or socio-cultural risk perceptions. In recent international social science discussions, however, a new research topic has emerged - those styles of reasoning and techniques of governance that are deployed to manage risk as a practical matter. My study explores these themes empirically by focusing on the specific habitual practices of risk management in the Finnish electricity infrastructure. The work develops various also semi-ethnographic inquiries into infrastructure risk techniques like monitor screening of real-time risks in electricity control rooms; the management of risks in a liberalized electricity market; the emergence of Finnish reasoning about blackouts from a specific historical background; and the ways in which electricity consumers respond to blackouts in their homes. In addition, the work reflects upon the position of a risk researcher in those situations when the research subjects do not define

  14. Retailers' risk management and vertical arrangements in electricity markets

    International Nuclear Information System (INIS)

    Boroumand, Raphaël Homayoun; Zachmann, Georg

    2012-01-01

    The failure of the asset-light retailer's organizational model is indicative of the incapacity of this organizational structure to manage efficiently the combination of sourcing and market risks in the current market environment. Because of the structural dimensions of electricity's market risks, a retailer's level of risk exposure is unknown ex ante and will only be revealed ex post when consumption is known. In contrast to the “textbook model” of electricity reforms, the paper demonstrates through numerical simulations that in the current market context pure portfolios of contracts are incomplete risk management instruments compared to physical hedging. The latter is critical to overcome the asset-light retailer's curse. - Highlights: ► The paper analyses the risks faced by electricity retailers. ► We study the limits of contractual hedging. ► Through numerical simulations, we compare the risk profiles of different portfolios of hedging. ► We demonstrate the superior efficiency of physical hedging.

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

    NARCIS (Netherlands)

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

    2015-01-01

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

  16. On the complex analysis of the reliability, safety, and economic efficiency of atomic electric power stations

    International Nuclear Information System (INIS)

    Emel'yanov, I.Ya.; Klemin, A.I.; Polyakov, E.F.

    1977-01-01

    The problem is posed of effectively increasing the engineering performance of nuclear electric power stations (APS). The principal components of the engineering performance of modern large APS are considered: economic efficiency, radiation safety, reliability, and their interrelationship. A nomenclature is proposed for the quantitative indices which most completely characterize the enumerated properties and are convenient for the analysis of the engineering performance. The urgent problem of developing a methodology for the complex analysis and optimization of the principal performance components is considered; this methodology is designed to increase the efficiency of the work on high-performance competitive APS. The principle of complex optimization of the reliability, safety, and economic-efficiency indices is formulated; specific recommendations are made for the practical realization of this principle. The structure of the complex quantiative analysis of the enumerated performance components is given. The urgency and promise of the complex approach to solving the problem of APS optimization is demonstrated, i.e., the solution of the problem of creating optimally reliable, fairly safe, and maximally economically efficient stations

  17. Risk analysis for decision support in electricity distribution system asset management: methods and frameworks for analysing intangible risks

    Energy Technology Data Exchange (ETDEWEB)

    Nordgaard, Dag Eirik

    2010-04-15

    During the last 10 to 15 years electricity distribution companies throughout the world have been ever more focused on asset management as the guiding principle for their activities. Within asset management, risk is a key issue for distribution companies, together with handling of cost and performance. There is now an increased awareness of the need to include risk analyses into the companies' decision making processes. Much of the work on risk in electricity distribution systems has focused on aspects of reliability. This is understandable, since it is surely an important feature of the product delivered by the electricity distribution infrastructure, and it is high on the agenda for regulatory authorities in many countries. However, electricity distribution companies are also concerned with other risks relevant for their decision making. This typically involves intangible risks, such as safety, environmental impacts and company reputation. In contrast to the numerous methodologies developed for reliability risk analysis, there are relatively few applications of structured analyses to support decisions concerning intangible risks, even though they represent an important motivation for decisions taken in electricity distribution companies. The overall objective of this PhD work has been to explore risk analysis methods that can be used to improve and support decision making in electricity distribution system asset management, with an emphasis on the analysis of intangible risks. The main contributions of this thesis can be summarised as: An exploration and testing of quantitative risk analysis (QRA) methods to support decisions concerning intangible risks; The development of a procedure for using life curve models to provide input to QRA models; The development of a framework for risk-informed decision making where QRA are used to analyse selected problems; In addition, the results contribute to clarify the basic concepts of risk, and highlight challenges

  18. Credit risk identification and suggestions of electricity market

    Science.gov (United States)

    He, Chuan; Wang, Haichao; Chen, Zhongyuan; Hao, Yuxing; Jiang, Hailong; Qian, Hanhan; Wang, Meibao

    2018-03-01

    The power industry has a long history of credit problems, and the power industry has credit problems such as power users defaulting on electricity bills before the new electricity reform. With the reform of the power system, the credit problems in the power industry will be more complicated. How to effectively avoid the risk factors existing in the course of market operation and how to safeguard the fairness and standardization of market operation is an urgent problem to be solved. This paper first describes the credit risk in power market, and analyzes the components of credit risk identification in power market, puts forward suggestions on power market risk management.

  19. STRUCTURAL FLUCTUATIONS, ELECTRICAL RESPONSE AND THE RELIABILITY OF NANOSTRUCTURES (FINAL REPORT)

    Energy Technology Data Exchange (ETDEWEB)

    Philip J. Rous; Ellen D. Williams; Michael S. Fuhrer

    2006-07-31

    The goal of the research supported by DOE-FG02-01ER45939 was to synthesize a number of experimental and theoretical approaches to understand the relationship between morphological fluctuations, the electrical response and the reliability (failure) of metallic nanostructures. The primary focus of our work was the study of metallic nanowires which we regard as prototypical of nanoscale interconnects. Our research plan has been to link together these materials properties and behaviors by understanding the phenomenon of, and the effects of electromigration at nanometer length scales. The thrust of our research has been founded on the concept that, for nanostructures where the surface-to-volume ratio is necessarily high, surface diffusion is the dominant mass transport mechanism that governs the fluctuations, electrical properties and failure modes of nanostructures. Our approach has been to develop experimental methods that permit the direct imaging of the electromagnetic distributions within nanostructures, their structural fluctuations and their electrical response. This experimental research is complemented by a parallel theoretical and computational program that describes the temporal evolution of nanostructures in response to current flow.

  20. Dynamic Self-Adaptive Reliability Control for Electric-Hydraulic Systems

    Directory of Open Access Journals (Sweden)

    Yi Wan

    2015-02-01

    Full Text Available The high-speed electric-hydraulic proportional control is a new development of the hydraulic control technique with high reliability, low cost, efficient energy, and easy maintenance; it is widely used in industrial manufacturing and production. However, there are still some unresolved challenges, the most notable being the requirements of high stability and real-time by the classical control algorithm due to its high nonlinear characteristics. We propose a dynamic self-adaptive mixed control method based on the least squares support vector machine (LSSVM and the genetic algorithm for high-speed electric-hydraulic proportional control systems in this paper; LSSVM is used to identify and adjust online a nonlinear electric-hydraulic proportional system, and the genetic algorithm is used to optimize the control law of the controlled system and dynamic self-adaptive internal model control and predictive control are implemented by using the mixed intelligent method. The internal model and the inverse control model are online adjusted together. At the same time, a time-dependent Hankel matrix is constructed based on sample data; thus finite dimensional solution can be optimized on finite dimensional space. The results of simulation experiments show that the dynamic characteristics are greatly improved by the mixed intelligent control strategy, and good tracking and high stability are met in condition of high frequency response.

  1. Review of the Brunswick Steam Electric Plant Probabilistic Risk Assessment

    International Nuclear Information System (INIS)

    Sattison, M.B.; Davis, P.R.; Satterwhite, D.G.; Gilmore, W.E.; Gregg, R.E.

    1989-11-01

    A review of the Brunswick Steam Electric Plant probabilistic risk Assessment was conducted with the objective of confirming the safety perspectives brought to light by the probabilistic risk assessment. The scope of the review included the entire Level I probabilistic risk assessment including external events. This is consistent with the scope of the probabilistic risk assessment. The review included an assessment of the assumptions, methods, models, and data used in the study. 47 refs., 14 figs., 15 tabs

  2. Analyzing the topological, electrical and reliability characteristics of a power transmission system for identifying its critical elements

    International Nuclear Information System (INIS)

    Zio, E.; Golea, L.R.

    2012-01-01

    The subject of this paper is the analysis of an electrical transmission system with the objective of identifying its most critical elements with respect to failures and attacks. The methodological approach undertaken is based on graph-theoretical (topological) network analysis. Four different perspectives of analysis are considered within the formalism of weighed networks, adding to the purely topological analysis of the system, the reliability and electrical characteristics of its components. In each phase of the analysis: i) a graph-theoretical representation is offered to highlight the structure of the most important system connections according to the particular characteristics examined (topological, reliability, electrical or electrical-reliability), ii) the classical degree index of a network node is extended to account for the different characteristics considered. The application of these concepts of analysis to an electrical transmission system of literature confirms the importance of different perspectives of analysis on such a critical infrastructure. - Highlights: ► We analyze a power system from topological, reliability and electrical perspectives. ► We rank critical components within a vulnerability assessment framework. ► We compute an extended degree to rank critical energy paths. ► We compare several analytical approaches and provide a table for choosing among them. ► We suggest network changes to increase the reliability of highly loaded energy paths.

  3. Applied risk analysis to the future Brazilian electricity generation matrix

    Energy Technology Data Exchange (ETDEWEB)

    Maues, Jair; Fernandez, Eloi; Correa, Antonio

    2010-09-15

    This study compares energy conversion systems for the generation of electrical power, with an emphasis on the Brazilian energy matrix. The financial model applied in this comparison is based on the Portfolio Theory, developed by Harry Markowitz. The risk-return ratio related to the electrical generation mix predicted in the National Energy Plan - 2030, published in 2006 by the Brazilian Energy Research Office, is evaluated. The increase of non-traditional renewable energy in this expected electrical generating mix, specifically, residues of sugar cane plantations and wind energy, reduce not only the risk but also the average cost of the kilowatt-hour generated.

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

    CERN Document Server

    2017-01-01

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

  5. Designing reliable supply chain network with disruption risk

    Directory of Open Access Journals (Sweden)

    Ali Bozorgi Amiri

    2013-01-01

    Full Text Available Although supply chains disruptions rarely occur, their negative effects are prolonged and severe. In this paper, we propose a reliable capacitated supply chain network design (RSCND model by considering random disruptions in both distribution centers and suppliers. The proposed model determines the optimal location of distribution centers (DC with the highest reliability, the best plan to assign customers to opened DCs and assigns opened DCs to suitable suppliers with lowest transportation cost. In this study, random disruption occurs at the location, capacity of the distribution centers (DCs and suppliers. It is assumed that a disrupted DC and a disrupted supplier may lose a portion of their capacities, and the rest of the disrupted DC's demand can be supplied by other DCs. In addition, we consider shortage in DCs, which can occur in either normal or disruption conditions and DCs, can support each other in such circumstances. Unlike other studies in the extent of literature, we use new approach to model the reliability of DCs; we consider a range of reliability instead of using binary variables. In order to solve the proposed model for real-world instances, a Non-dominated Sorting Genetic Algorithm-II (NSGA-II is applied. Preliminary results of testing the proposed model of this paper on several problems with different sizes provide seem to be promising.

  6. A reliable method for intracranial electrode implantation and chronic electrical stimulation in the mouse brain.

    Science.gov (United States)

    Jeffrey, Melanie; Lang, Min; Gane, Jonathan; Wu, Chiping; Burnham, W McIntyre; Zhang, Liang

    2013-08-06

    Electrical stimulation of brain structures has been widely used in rodent models for kindling or modeling deep brain stimulation used clinically. This requires surgical implantation of intracranial electrodes and subsequent chronic stimulation in individual animals for several weeks. Anchoring screws and dental acrylic have long been used to secure implanted intracranial electrodes in rats. However, such an approach is limited when carried out in mouse models as the thin mouse skull may not be strong enough to accommodate the anchoring screws. We describe here a screw-free, glue-based method for implanting bipolar stimulating electrodes in the mouse brain and validate this method in a mouse model of hippocampal electrical kindling. Male C57 black mice (initial ages of 6-8 months) were used in the present experiments. Bipolar electrodes were implanted bilaterally in the hippocampal CA3 area for electrical stimulation and electroencephalographic recordings. The electrodes were secured onto the skull via glue and dental acrylic but without anchoring screws. A daily stimulation protocol was used to induce electrographic discharges and motor seizures. The locations of implanted electrodes were verified by hippocampal electrographic activities and later histological assessments. Using the glue-based implantation method, we implanted bilateral bipolar electrodes in 25 mice. Electrographic discharges and motor seizures were successfully induced via hippocampal electrical kindling. Importantly, no animal encountered infection in the implanted area or a loss of implanted electrodes after 4-6 months of repetitive stimulation/recording. We suggest that the glue-based, screw-free method is reliable for chronic brain stimulation and high-quality electroencephalographic recordings in mice. The technical aspects described this study may help future studies in mouse models.

  7. Review of the human reliability analysis performed for Empire State Electric Energy Research Corporation

    International Nuclear Information System (INIS)

    Swart, D.; Banz, I.

    1985-01-01

    The Empire State Electric Energy Research Corporation (ESEERCO) commissioned Westinghouse to conduct a human reliability analysis to identify and quantify human error probabilities associated with operator actions for four specific events which may occur in light water reactors: loss of coolant accident, steam generator tube rupture, steam/feed line break, and stuck open pressurizer spray valve. Human Error Probabilities (HEPs) derived from Swain's Technique for Human Error Rate Prediction (THERP) were compared to data obtained from simulator exercises. A correlation was found between the HEPs derived from Swain and the results of the simulator data. The results of this study provide a unique insight into human factors analysis. The HEPs obtained from such probabilistic studies can be used to prioritize scenarios for operator training situations, and thus improve the correlation between simulator exercises and real control room experiences

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

    International Nuclear Information System (INIS)

    Yamamoto, Satoshi

    2014-01-01

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

  9. Economic evaluation of reliability-centred maintenance (RCM): an electricity transmission industry perspective

    International Nuclear Information System (INIS)

    Bowler, D.J.; Primrose, P.L.; Leonard, R.

    1995-01-01

    Traditional approaches to appraising the introduction of reliability centred maintenance (RCM) are shown to exhibit severe limitations. In particular, the economic implications surrounding its adoption are repeatedly mis-stated, with the consequence that organisations may be investing in unprofitable RCM ventures. Previously quoted benefits are examined and, contrary to established opinion, it is shown that these 'generalised' statements, once redeemed, are able to be quantified. The paper then proceeds to describe a financial methodology, developed by NGC and UMIST, by which the introduction of RCM can be evaluated. Moreover, it shows that, by regarding RCM as an investment decision, rather than an 'act of faith', the economic viability of a potential application can be determined before vital resources are committed. Finally, it is demonstrated that when the methodology is applied within the context of the electricity transmission industry, the economic case underlying the adoption of RCM can be realistically appraised. (author)

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

    International Nuclear Information System (INIS)

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

    1977-01-01

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

  11. Updated Value of Service Reliability Estimates for Electric Utility Customers in the United States

    Energy Technology Data Exchange (ETDEWEB)

    Sullivan, Michael [Nexant Inc., Burlington, MA (United States); Schellenberg, Josh [Nexant Inc., Burlington, MA (United States); Blundell, Marshall [Nexant Inc., Burlington, MA (United States)

    2015-01-01

    This report updates the 2009 meta-analysis that provides estimates of the value of service reliability for electricity customers in the United States (U.S.). The meta-dataset now includes 34 different datasets from surveys fielded by 10 different utility companies between 1989 and 2012. Because these studies used nearly identical interruption cost estimation or willingness-to-pay/accept methods, it was possible to integrate their results into a single meta-dataset describing the value of electric service reliability observed in all of them. Once the datasets from the various studies were combined, a two-part regression model was used to estimate customer damage functions that can be generally applied to calculate customer interruption costs per event by season, time of day, day of week, and geographical regions within the U.S. for industrial, commercial, and residential customers. This report focuses on the backwards stepwise selection process that was used to develop the final revised model for all customer classes. Across customer classes, the revised customer interruption cost model has improved significantly because it incorporates more data and does not include the many extraneous variables that were in the original specification from the 2009 meta-analysis. The backwards stepwise selection process led to a more parsimonious model that only included key variables, while still achieving comparable out-of-sample predictive performance. In turn, users of interruption cost estimation tools such as the Interruption Cost Estimate (ICE) Calculator will have less customer characteristics information to provide and the associated inputs page will be far less cumbersome. The upcoming new version of the ICE Calculator is anticipated to be released in 2015.

  12. The Reliability of EMU FIscal Indicators: Risks and Safeguards

    OpenAIRE

    Fabrizio Balassone; Daniele Franco; Stefania Zotteri

    2007-01-01

    The reliability of EMU�s fiscal indicators has been questioned by recent episodes of large upward deficit revisions. This paper discusses the causes of such revisions in order to identify ways to improve monitoring. The computation of EMU�s deficit indicator involves the assessment of accrued revenue and expenditure and the identification of transactions in financial assets. Both can open margins for opportunistic accounting. However, crosschecks between deficit and changes in gross nomin...

  13. Inter- and intra- observer reliability of risk assessment of repetitive work without an explicit method.

    Science.gov (United States)

    Eliasson, Kristina; Palm, Peter; Nyman, Teresia; Forsman, Mikael

    2017-07-01

    A common way to conduct practical risk assessments is to observe a job and report the observed long term risks for musculoskeletal disorders. The aim of this study was to evaluate the inter- and intra-observer reliability of ergonomists' risk assessments without the support of an explicit risk assessment method. Twenty-one experienced ergonomists assessed the risk level (low, moderate, high risk) of eight upper body regions, as well as the global risk of 10 video recorded work tasks. Intra-observer reliability was assessed by having nine of the ergonomists repeat the procedure at least three weeks after the first assessment. The ergonomists made their risk assessment based on his/her experience and knowledge. The statistical parameters of reliability included agreement in %, kappa, linearly weighted kappa, intraclass correlation and Kendall's coefficient of concordance. The average inter-observer agreement of the global risk was 53% and the corresponding weighted kappa (K w ) was 0.32, indicating fair reliability. The intra-observer agreement was 61% and 0.41 (K w ). This study indicates that risk assessments of the upper body, without the use of an explicit observational method, have non-acceptable reliability. It is therefore recommended to use systematic risk assessment methods to a higher degree. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  14. RISKS OF LOSING CONTROLLABILITY WHILE LIBERALIZING THE ELECTRIC POWER INDUSTRY

    Directory of Open Access Journals (Sweden)

    Yu. S. Petrusha

    2015-01-01

    Full Text Available The paper analyses controllability qua a reliability characteristic of the electric-power grid controlling system. The following notions are used: the object (environment susceptibility towards the control stimuli, the controlling system adequacy, environment of the secure functioning. The author points to the necessity of accounting for the limitations of technological and organizational character. While liberalizing the electric-power industry, the backbone control-principle “the industry functioning reliability” is being replaced with the principle of “profit-making” that requires complete restatement of the control philosophy.The conflict between commercial benefit gaining and the reliability assurance expenses leads to losing controllability in all the managerial links and to probable catastrophic consequences. The recapitulation of the Russian Federation power industry privatization substantiates concerns of the liberal ideas poor survivability in the ex-Soviet territories. The results of degradation of the secure-functioning environment demonstrate affinity of the mechanisms that triggered the Chernobyl NPP, Fukusima NPP, and Sayan-Shushenskya HPP disasters. Securing reliability of the strategic objects leaves the competence boundaries of the electricpower industry.The topical issue of Belorussian electric-power industry functioning and developing is the combination of technical re-equipment (developing the operational dispatch management and the control-system organizational modernizing in general with gradual and controllable transition to the market mechanisms of functioning. Herewith, preserving the state monopoly on regime provision for the operation of the electric-power system should not leave out the industry appeal for outside investment and is regulated by the optimal degree and intensity of the state participation in governing the electric-power supply industry. The distinction of privatization models and the stages

  15. Reliability Indicators of Urban Electric Network Schemes for Supply of Second and Third Category Consumers

    Directory of Open Access Journals (Sweden)

    M. A. Korotkevich

    2012-01-01

    Full Text Available The paper considers two schemes of the urban distributive electric network for supply of the second and third category consumers for whom indicators of reliability have been determined.As for a network scheme of the 2nd category it has been determined that while installing low-oil and vacuum switches at a distributive point the most remote transformer substation has the highest non-availability  factor which is higher of the corresponding non-availability  factor of the nearest transformer substation by 1,21–1,23 fold  accordingly.As for a network scheme of the 3rd category consumers it has been obtained the data that reliability of consumers receiving supply from bus-bars of transformer substations with 0,38 kW voltage changes  significantly (by 1,2–1,9-fold while changing a breakpoint of the network with 10 kW voltage.

  16. Evaluation of Reliability in Risk-Constrained Scheduling of Autonomous Microgrids with Demand Response and Renewable Resources

    DEFF Research Database (Denmark)

    Vahedipour-Dahraie, Mostafa; Anvari-Moghaddam, Amjad; Guerrero, Josep M.

    2018-01-01

    of microgrid. Moreover, the impacts of different VOLL and risk aversion parameter are illustrated on the system reliability. Extensive simulation results are also presented to illustrate the impact of risk aversion on system security issues with and without DR. Numerical results demonstrate the advantages......Uncertain natures of the renewable energy resources and consumers’ participation in demand response (DR) programs have introduced new challenges to the energy and reserve scheduling of microgrids, particularly in the autonomous mode. In this paper, a risk-constrained stochastic framework...... is presented to maximize the expected profit of a microgrid operator under uncertainties of renewable resources, demand load and electricity price. In the proposed model, the trade-off between maximizing the operator’s expected profit and the risk of getting low profits in undesired scenarios is modeled...

  17. Key attributes of the SAPHIRE risk and reliability analysis software for risk-informed probabilistic applications

    International Nuclear Information System (INIS)

    Smith, Curtis; Knudsen, James; Kvarfordt, Kellie; Wood, Ted

    2008-01-01

    The Idaho National Laboratory is a primary developer of probabilistic risk and reliability analysis (PRRA) tools, dating back over 35 years. Evolving from mainframe-based software, the current state-of-the-practice has led to the creation of the SAPHIRE software. Currently, agencies such as the Nuclear Regulatory Commission, the National Aeronautics and Aerospace Agency, the Department of Energy, and the Department of Defense use version 7 of the SAPHIRE software for many of their risk-informed activities. In order to better understand and appreciate the power of software as part of risk-informed applications, we need to recall that our current analysis methods and solution methods have built upon pioneering work done 30-40 years ago. We contrast this work with the current capabilities in the SAPHIRE analysis package. As part of this discussion, we provide information for both the typical features and special analysis capabilities, which are available. We also present the application and results typically found with state-of-the-practice PRRA models. By providing both a high-level and detailed look at the SAPHIRE software, we give a snapshot in time for the current use of software tools in a risk-informed decision arena

  18. Risk and investment management in liberalized electricity markets

    International Nuclear Information System (INIS)

    Lemming, J.

    2003-09-01

    Electricity markets around the world are currently undergoing a liberalization process that changes the way electricity is traded and priced as a commodity. The electricity system has unique technical characteristics and the importance of electricity in today's information society is significant. The liberalization will not change the fact that politicians and regulators will be held responsible for keeping electricity on reasonable costs. What changes is the tool used by regulators to accomplish this task. The introduction of competitive markets implies that market participants will be held financial responsible for their decisions. System operators remain responsible for the physical balancing, thus electricity markets will remain strongly regulated even after liberalization. The hypothesis of this thesis is that the relevance of financial tools for electricity market risk management depends critically on the technical characteristics of electricity assets and on the demands placed by the stakeholders in the electricity sector. In many cases such technical characteristics and stakeholder demands will imply a need for revised and renewed tools compared to those used for portfolios of financial assets. (BA)

  19. A reliability design method for a lithium-ion battery pack considering the thermal disequilibrium in electric vehicles

    Science.gov (United States)

    Xia, Quan; Wang, Zili; Ren, Yi; Sun, Bo; Yang, Dezhen; Feng, Qiang

    2018-05-01

    With the rapid development of lithium-ion battery technology in the electric vehicle (EV) industry, the lifetime of the battery cell increases substantially; however, the reliability of the battery pack is still inadequate. Because of the complexity of the battery pack, a reliability design method for a lithium-ion battery pack considering the thermal disequilibrium is proposed in this paper based on cell redundancy. Based on this method, a three-dimensional electric-thermal-flow-coupled model, a stochastic degradation model of cells under field dynamic conditions and a multi-state system reliability model of a battery pack are established. The relationships between the multi-physics coupling model, the degradation model and the system reliability model are first constructed to analyze the reliability of the battery pack and followed by analysis examples with different redundancy strategies. By comparing the reliability of battery packs of different redundant cell numbers and configurations, several conclusions for the redundancy strategy are obtained. More notably, the reliability does not monotonically increase with the number of redundant cells for the thermal disequilibrium effects. In this work, the reliability of a 6 × 5 parallel-series configuration is the optimal system structure. In addition, the effect of the cell arrangement and cooling conditions are investigated.

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

    Science.gov (United States)

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

    2012-01-01

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

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

    Science.gov (United States)

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

    2013-11-01

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

  2. Risk of neurological diseases among survivors of electric shocks

    DEFF Research Database (Denmark)

    Grell, Kathrine; Meersohn, Andrea; Schüz, Joachim

    2012-01-01

    Several studies suggest a link between electric injuries and neurological diseases, where electric shocks may explain elevated risks for neuronal degeneration and, subsequently, neurological diseases. We conducted a retrospective cohort study on the risk of neurological diseases among people...... in Denmark who had survived an electric accident in 1968-2008. The cohort included 3,133 people and occurrences of neurological diseases were determined by linkage to the nationwide population-based Danish National Register of Patients. The numbers of cases observed at first hospital contact in the cohort...... were compared with the respective rates of first hospital contacts for neurological diseases in the general population. We observed significantly increased risks for peripheral nerve diseases (standardized hospitalization ratio (SHR), 1.66; 95% confidence interval (CI), 1.22-2.22), for migraine (SHR, 1...

  3. 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.

  4. 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.

  5. Improving electrical power systems reliability through locally controlled distributed curtailable load

    Science.gov (United States)

    Dehbozorgi, Mohammad Reza

    2000-10-01

    Improvements in power system reliability have always been of interest to both power companies and customers. Since there are no sizable electrical energy storage elements in electrical power systems, the generated power should match the load demand at any given time. Failure to meet this balance may cause severe system problems, including loss of generation and system blackouts. This thesis proposes a methodology which can respond to either loss of generation or loss of load. It is based on switching of electric water heaters using power system frequency as the controlling signal. The proposed methodology encounters, and the thesis has addressed, the following associated problems. The controller must be interfaced with the existing thermostat control. When necessary to switch on loads, the water in the tank should not be overheated. Rapid switching of blocks of load, or chattering, has been considered. The contributions of the thesis are: (A) A system has been proposed which makes a significant portion of the distributed loads connected to a power system to behave in a predetermined manner to improve the power system response during disturbances. (B) The action of the proposed system is transparent to the customers. (C) The thesis proposes a simple analysis for determining the amount of such loads which might be switched and relates this amount to the size of the disturbances which can occur in the utility. (D) The proposed system acts without any formal communication links, solely using the embedded information present system-wide. (E) The methodology of the thesis proposes switching of water heater loads based on a simple, localized frequency set-point controller. The thesis has identified the consequent problem of rapid switching of distributed loads, which is referred to as chattering. (F) Two approaches have been proposed to reduce chattering to tolerable levels. (G) A frequency controller has been designed and built according to the specifications required to

  6. Power transformer reliability modelling

    NARCIS (Netherlands)

    Schijndel, van A.

    2010-01-01

    Problem description Electrical power grids serve to transport and distribute electrical power with high reliability and availability at acceptable costs and risks. These grids play a crucial though preferably invisible role in supplying sufficient power in a convenient form. Today’s society has

  7. 'Living PRA' concept for plant risk: Reliability and availability tracking

    International Nuclear Information System (INIS)

    Sancaktar, S.; Sharp, D.R.

    1985-01-01

    The 'Living PRA' (Probabilistic Risk Assessment) is based on placing a PRA plant model on an interactive computer. This model consists of fault tree analyses for plant systems, event tree analyses for abnormal events and site specific consequence analysis for public and/or financial risks, for a nuclear power plant. A living PRA allows updates and sensitivity analyses by the plant owner throughout the lifetime of a plant. Recently, event and fault trees from two major PRAs were placed in a computerized format. The BYRON PRA study and the Living PRA and Economic Risk examples for Indian Point Unit-3 enabled analysts to gain experience and insight into the problems of plant operation. The above concept is well established for the Nuclear Power Plant evaluation. It has been also used for evaluation of processing facilities. In these studies, systems modeling was carried out by using the GRAFTER system for automated fault tree construction. Presently both the tools and the experience exists to set up useful and viable living PRA models for nuclear and chemical processing plants to enhance risk management by the plant owners through in-house use of micro computer based models

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

    DEFF Research Database (Denmark)

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

    2016-01-01

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

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

    Science.gov (United States)

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

    2014-05-01

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

  10. A Novel Risk Scoring System Reliably Predicts Readmission Following Pancreatectomy

    Science.gov (United States)

    Valero, Vicente; Grimm, Joshua C.; Kilic, Arman; Lewis, Russell L.; Tosoian, Jeffrey J.; He, Jin; Griffin, James; Cameron, John L.; Weiss, Matthew J.; Vollmer, Charles M.; Wolfgang, Christopher L.

    2015-01-01

    Background Postoperative readmissions have been proposed by Medicare as a quality metric and may impact provider reimbursement. Since readmission following pancreatectomy is common, we sought to identify factors associated with readmission in order to establish a predictive risk scoring system (RSS). Study Design A retrospective analysis of 2,360 pancreatectomies performed at nine, high-volume pancreatic centers between 2005 and 2011 was performed. Forty-five factors strongly associated with readmission were identified. To derive and validate a RSS, the population was randomly divided into two cohorts in a 4:1 fashion. A multivariable logistic regression model was constructed and scores were assigned based on the relative odds ratio of each independent predictor. A composite Readmission After Pancreatectomy (RAP) score was generated and then stratified to create risk groups. Results Overall, 464 (19.7%) patients were readmitted within 90-days. Eight pre- and postoperative factors, including prior myocardial infarction (OR 2.03), ASA Class ≥ 3 (OR 1.34), dementia (OR 6.22), hemorrhage (OR 1.81), delayed gastric emptying (OR 1.78), surgical site infection (OR 3.31), sepsis (OR 3.10) and short length of stay (OR 1.51), were independently predictive of readmission. The 32-point RAP score generated from the derivation cohort was highly predictive of readmission in the validation cohort (AUC 0.72). The low (0-3), intermediate (4-7) and high risk (>7) groups correlated to 11.7%, 17.5% and 45.4% observed readmission rates, respectively (preadmission following pancreatectomy. Identification of patients with increased risk of readmission using the RAP score will allow efficient resource allocation aimed to attenuate readmission rates. It also has potential to serve as a new metric for comparative research and quality assessment. PMID:25797757

  11. 18-month outlook : an assessment of the reliability of the Ontario Electricity System

    International Nuclear Information System (INIS)

    2005-01-01

    This paper provides an 18 month forecast of the Ontario electricity system, as well as an outline of activities and recent developments relating to the issue of reliability. An additional aim of the paper was to identify potentially adverse conditions that may require adjustment or coordination of maintenance plans for generation and transmission equipment. Requests for proposals (RFPs) for renewable generation within the specified time-frame were also discussed, as well as the return to service of Ontario Power Generation's Pickering Unit 1. Reduced reserve levels for the summer of 2005 were anticipated, and details of forecasted peak demand, generator maintenance, new generation and price-responsive demand adjustments and forced outage rates were presented. It was suggested that adequate market mechanisms were in place to manage reserve levels. Developments concerning the new Parkway Transformer station were reviewed. A resource outlook was provided. Available resources were expected to exceed planning requirements with the exception of 6 weeks in the summer of 2005. A projected capacity increase was also anticipated, due to the return of Pickering 1 and an additional 515 MW in the fall of 2005. Price-responsive demands were forecasted to exceed 650 MW due to increases in dispatchable load. It was suggested that in order to ensure power demand during peak periods, imports may be required under extreme weather conditions, combined with the possible deferral or cancellation of generation maintenance. Transmission impacts due to shutdowns were discussed. Voltage system requirements were reviewed, along with details of the installation of additional shunt capacitors and transformer controls. The electricity market was reviewed in the context of current overall economic conditions. Data forecasting normal peak demand was presented for the entire outlook period. 19 tabs., 10 figs

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

    International Nuclear Information System (INIS)

    Salmela, Olli

    2005-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2005-08-01

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

  14. Reliability centered maintenance as an optimization tool for electrical power plants

    International Nuclear Information System (INIS)

    Jacquot, J.P.; Bryla, P.; Martin-Mattei, C.; Meuwisse, C.

    1997-08-01

    Seven years ago, Electricite de France launched a Reliability Centered Maintenance (RCM) pilot project to optimize preventive maintenance for its nuclear power plants. After a feasibility study, a RCM method was standardized. It is now applied on a large scale to the 50 EDF nuclear units. A RCM workstation based on this standardized method has been developed and is now used in each plant. In the next step, it is considered whether a Risk based Approach can be included in this RCM process in order to analyze critical passive components such as pipes and supports. Considering the potential advantages of these optimization techniques, a dedicated process has been also developed for maintenance of future plants, gas turbines, or nuclear units. A survey of these different developments of methods and tools is presented. (author)

  15. Risk management in electricity markets emphasizing transmission congestion

    International Nuclear Information System (INIS)

    Kristiansen, Tarjei

    2004-01-01

    This thesis analyzes transmission pricing, transmission congestion risks and their associated hedging instruments as well as mechanisms for stimulating investments in transmission expansion. An example of risk management in the case of a hydropower producer is included. After liberalization and restructuring of electricity markets, risk management has become important. In particular the thesis analyzes risks due to transmission congestion both in the short- and long-term (investments) for market players such as generators, loads, traders, independent system operators and merchant investors. The work is focused on the northeastern United States electricity markets and the Nordic electricity markets. The first part of the thesis reviews the literature related to the eight research papers in the thesis. This describes the risks that are relevant for an electricity market player and how these can be managed. Next, the basic ingredients of a competitive electricity market are described including the design of the system operator. The transmission pricing method is decisive for hedging against transmission congestion risks and there is an overview of transmission pricing models considering their similarities and differences. Depending on the transmission pricing method used, locational or area (zonal) pricing, the electricity market players can use financial transmission rights or Contracts for Differences, respectively. In the long-term it is important to create mechanisms for investments in transmission expansion and the thesis describes one possible approach and its potential problems. The second part comprises eight research papers. It presents empirical analyses of existing markets for transmission congestion derivatives, theoretical analyses of transmission congestion derivatives, modeling of merchant long-term financial transmission rights, theoretical analysis of the risks of the independent system operator in providing financial transmission rights, an analysis

  16. Consortium for Electric Reliability Technology Solutions Grid of the Future White Paper on Review of Recent Reliability Issues and Systems Events

    Energy Technology Data Exchange (ETDEWEB)

    Hauer, John F.; Dagle, Jeffery E.

    1999-12-01

    This report is one of six reports developed under the U.S. Department of Energy (DOE) program in Power System Integration and Reliability (PSIR). The objective of this report is to review, analyze, and evaluate critical reliability issues demonstrated by recent disturbance events in the North America power system. Eleven major disturbances are examined, most occurring in this decade. The strategic challenge is that the pattern of technical need has persisted for a long period of time. For more than a decade, anticipation of market deregulation has been a major disincentive to new investments in system capacity. It has also inspired reduced maintenance of existing assets. A massive infusion of better technology is emerging as the final option to continue reliable electrical services. If an investment in better technology will not be made in a timely manner, then North America should plan its adjustments to a very different level of electrical service. It is apparent that technical operations staff among the utilities can be very effective at marshaling their forces in the immediate aftermath of a system emergency, and that serious disturbances often lead to improved mechanisms for coordinated operation. It is not at all apparent that such efforts can be sustained through voluntary reliability organizations in which utility personnel external to those organizations do most of the technical work. The eastern interconnection shows several situations in which much of the technical support has migrated from the utilities to the Independent System Operator (ISO), and the ISO staffs or shares staff with the regional reliability council. This process may be a natural and very positive consequence of utility restructuring. If so, the process should be expedited in regions where it is less advanced.

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

    Science.gov (United States)

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

    2014-08-01

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

  18. INCREASING RELIABILITY OF STEPPED AUTOMATIC STARTING AND RHEOSTAT BREAKING SYSTEM OF ELECTRIC TRAINS ER9T AND EPL9T

    Directory of Open Access Journals (Sweden)

    N. H. Visin

    2010-06-01

    Full Text Available The article examines transitional processes in the power circuit of tractive motors and their influence on the work of stepped automatic starting of electric trains ER9T and EPL9T. The recommendations for increasing the reliability of operation of multiple-unit rolling stock are proposed.

  19. Electricity market risk management using forward contracts with bilateral options

    International Nuclear Information System (INIS)

    Chung, T.S.; Yu, C.W.; Wong, K.P.; Zhang, S.H.

    2003-01-01

    Extreme short-term price volatility in competitive electricity markets creates the need for risk management arrangements. A new electricity forward contract with bilateral financial options is introduced, which allows both seller and buyer to take advantage of flexibility in generation and consumption to obtain monetary benefits while simultaneously removing the risk of market price fluctuations. The option theory is incorporated to formulate the contract price. The strike prices of options are derived from solving an equilibrium model in which both the buyer and the seller aim to maximise their own profit. Theoretical analysis shows that the proposed optional forward contract presents a more equitable and reasonable payoff structure that allows the buyer and seller to earn a larger overall expected benefit, and the contractual arrangement supports efficiency in economic dispatch of electricity production and consumption. The insights obtained from these results will be helpful to participants in the contractual decision-making process. (Author)

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

    Science.gov (United States)

    Macagnino, Sandro; Steinert, Tilman; Uhlmann, Carmen

    2018-05-01

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

  1. Spacecraft electrical power subsystem: Failure behavior, reliability, and multi-state failure analyses

    International Nuclear Information System (INIS)

    Kim, So Young; Castet, Jean-Francois; Saleh, Joseph H.

    2012-01-01

    This article investigates the degradation and failure behavior of spacecraft electrical power subsystem (EPS) on orbit. First, this work provides updated statistical reliability and multi-state failure analyses of spacecraft EPS and its different constituents, namely the batteries, the power distribution, and the solar arrays. The EPS is shown to suffer from infant mortality and to be a major driver of spacecraft unreliability. Over 25% of all spacecraft failures are the result of EPS failures. As a result, satellite manufacturers may wish to pursue targeted improvement to this subsystem, either through better testing or burn-in procedures, better design or parts selection, or additional redundancy. Second, this work investigates potential differences in the EPS degradation and failure behavior for spacecraft in low earth orbits (LEO) and geosynchronous orbits (GEO). This analysis was motivated by the recognition that the power/load cycles and the space environment are significantly different in LEO and GEO, and as such, they may result in different failure behavior for the EPS in these two types of orbits. The results indicate, and quantify the extent to which, the EPS fails differently in LEO and GEO, both in terms of frequency and severity of failure events. A casual summary of the findings can be stated as follows: the EPS fails less frequently but harder (with fatal consequences to the spacecraft) in LEO than in GEO.

  2. Puget Sound Area Electric Reliability Plan : Appendix E, Transmission Reinforcement Analysis.

    Energy Technology Data Exchange (ETDEWEB)

    United States. Bonneville Power Administration.

    1992-04-01

    The purpose of this appendix to the draft environmental impact statement (EIS) report is to provide an update of the latest study work done on transmission system options for the Puget Sound Area Electric Reliability Plan. Also included in the attachments to the EIS are 2 reports analyzing the voltage stability of the Puget Sound transmission system and a review by Power Technologies, Inc. of the BPA voltage stability analysis and reactive options. Five transmission line options and several reactive options are presently being considered as possible solutions to the PSAFRP by the Transmission Team. The first two line options would be built on new rights-of way adjacent (as much as possible) to existing corridors. The reactive options would optimize the existing transmission system capability by adding new stations for series capacitors and/or switchgear. The other three line options are rebuilds or upgrades of existing cross mountain transmission lines. These options are listed below and include a preliminary assessment of the additional transmission system reinforcement required to integrate the new facilities into the existing transmission system. Plans were designed to provide at least 500 MVAR reactive margin.

  3. Reliability of the electric power supply in the safety apparatus of nuclear power plants: a comparative analysis

    International Nuclear Information System (INIS)

    Cruz, L.A.

    1992-01-01

    This paper discusses the risk of total loss of electric power supply to the Class 1E system. Two alternatives are focused: a system with two off-site and two onsite power supplies emergency power supply, as recommended by the American Regulations, and a system with only one off-site and four on-site power supplies, applicable when two off-site are not available. To allow the fact that the equipment can be repaired, the method proper involves use of the Markov model, with which one can find, for each configuration of the system, the change over time of the probability of a simultaneous failure of all power sources. The sensitivity of each parameter is studied in each case and, on the basis of the results of the study, the author conclude that the system with two off-site power supplies is preferable in all alternatives analysed, although the system with one off-site power supply can be adopted with high reliability diesel-generators. (author)

  4. An assessment of the reliability of the Ontario electricity system : 18-month outlook from April 2004 to September 2005

    International Nuclear Information System (INIS)

    2004-01-01

    This report presents a resource assessment by the Independent Electricity Market Operator (IMO) for the 18-month period from April 2004 to September 2005. It is based on the IMO's forecast of electricity demand. The information was provided by power generators in Ontario. The outlook for the electricity system has improved due to the return to service of 3 nuclear units and the addition of more than 700 MW of generation. The return to service of the nuclear units has decreased Ontario's reliance on imports to help meet energy demand in the province. The shutdown of 1150 MW of coal-fired generation at Lakeview Thermal Generating Station in Mississauga emphasizes the importance of improving transmission and generation capacity in the Toronto area. This report also includes updated values for existing resource scenarios and planned resource scenarios. The reliability of Ontario's transmission system was also assessed along with the adequacy of the existing resource to meet the forecast demand. The existing installed generation resources include 5 nuclear stations generating 10,831 MW of electricity, 5 coal stations generating 7,564 MW of electricity, 22 oil and gas fired stations generating 4,364 MW of electricity, 61 hydroelectric stations generating 7,676 MW of electricity, and 2 other stations generating 66 MW of electricity. Although the existing resource scenario is better than in previous reports, imports will be required under extreme weather conditions to help meet electricity demand in Ontario during peak periods. 21 tabs., 10 figs

  5. Use of reliability engineering tools in safety and risk assessment of nuclear facilities

    Energy Technology Data Exchange (ETDEWEB)

    Raso, Amanda Laureano; Vasconcelos, Vanderley de; Marques, Raíssa Oliveira; Soares, Wellington Antonio; Mesquita, Amir Zacarias, E-mail: amandaraso@hotmail.com, E-mail: vasconv@cdtn.br, E-mail: raissaomarques@gmail.com, E-mail: soaresw@cdtn.br, E-mail: amir@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil). Serviço de Tecnologia de Reatores

    2017-07-01

    Safety, reliability and availability are fundamental criteria in design, construction and operation of nuclear facilities, as nuclear power plants. Deterministic and probabilistic risk assessments of such facilities are required by regulatory authorities in order to meet licensing regulations, contributing to assure safety, as well as reduce costs and environmental impacts. Probabilistic Risk Assessment has become an important part of licensing requirements of the nuclear power plants in Brazil and in the world. Risk can be defined as a qualitative and/or quantitative assessment of accident sequence frequencies (or probabilities) and their consequences. Risk management is a systematic application of management policies, procedures and practices to identify, analyze, plan, implement, control, communicate and document risks. Several tools and computer codes must be combined, in order to estimate both probabilities and consequences of accidents. Event Tree Analysis (ETA), Fault Tree Analysis (FTA), Reliability Block Diagrams (RBD), and Markov models are examples of evaluation tools that can support the safety and risk assessment for analyzing process systems, identifying potential accidents, and estimating consequences. Because of complexity of such analyzes, specialized computer codes are required, such as the reliability engineering software develop by Reliasoft® Corporation. BlockSim (FTA, RBD and Markov models), RENO (ETA and consequence assessment), Weibull++ (life data and uncertainty analysis), and Xfmea (qualitative risk assessment) are some codes that can be highlighted. This work describes an integrated approach using these tools and software to carry out reliability, safety, and risk assessment of nuclear facilities, as well as, and application example. (author)

  6. Developments in Levee Reliability and Flood Risk Analysis in the Netherlands

    NARCIS (Netherlands)

    Jonkman, S.N.; Schweckendiek, T.

    2015-01-01

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

  7. Use of reliability engineering tools in safety and risk assessment of nuclear facilities

    International Nuclear Information System (INIS)

    Raso, Amanda Laureano; Vasconcelos, Vanderley de; Marques, Raíssa Oliveira; Soares, Wellington Antonio; Mesquita, Amir Zacarias

    2017-01-01

    Safety, reliability and availability are fundamental criteria in design, construction and operation of nuclear facilities, as nuclear power plants. Deterministic and probabilistic risk assessments of such facilities are required by regulatory authorities in order to meet licensing regulations, contributing to assure safety, as well as reduce costs and environmental impacts. Probabilistic Risk Assessment has become an important part of licensing requirements of the nuclear power plants in Brazil and in the world. Risk can be defined as a qualitative and/or quantitative assessment of accident sequence frequencies (or probabilities) and their consequences. Risk management is a systematic application of management policies, procedures and practices to identify, analyze, plan, implement, control, communicate and document risks. Several tools and computer codes must be combined, in order to estimate both probabilities and consequences of accidents. Event Tree Analysis (ETA), Fault Tree Analysis (FTA), Reliability Block Diagrams (RBD), and Markov models are examples of evaluation tools that can support the safety and risk assessment for analyzing process systems, identifying potential accidents, and estimating consequences. Because of complexity of such analyzes, specialized computer codes are required, such as the reliability engineering software develop by Reliasoft® Corporation. BlockSim (FTA, RBD and Markov models), RENO (ETA and consequence assessment), Weibull++ (life data and uncertainty analysis), and Xfmea (qualitative risk assessment) are some codes that can be highlighted. This work describes an integrated approach using these tools and software to carry out reliability, safety, and risk assessment of nuclear facilities, as well as, and application example. (author)

  8. Proceeding of 35th domestic symposium on applications of structural reliability and risk assessment methods to nuclear power plants

    International Nuclear Information System (INIS)

    2005-06-01

    As the 35th domestic symposium of Atomic Energy Research Committee, the Japan Welding Engineering Society, the symposium was held titled as Applications of structural reliability/risk assessment methods to nuclear energy'. Six speakers gave lectures titled as 'Structural reliability and risk assessment methods', 'Risk-informed regulation of US nuclear energy and role of probabilistic risk assessment', 'Reliability and risk assessment methods in chemical plants', 'Practical structural design methods based on reliability in architectural and civil areas', 'Maintenance activities based on reliability in thermal power plants' and 'LWR maintenance strategies based on Probabilistic Fracture Mechanics'. (T. Tanaka)

  9. The perception of risks related to electricity generation

    Energy Technology Data Exchange (ETDEWEB)

    Midden, C J; Daamen, D D; Verplanken, B

    1987-01-01

    Some of the key findings are discussed of psychological research on the perception of risks and attitudes with respect to the use of uranium and coal for electricity generation. It appears that attitudes are mostly not based on ideology but rather determined by a trade-off of expected risks and advantages. Lay estimates of probabilities are compared with expert judgements. In the last section attitudes of people living near existing or planned power plants are analyzed. Serious doubts are raised about the possibilities to give residents economic compensation for exposure to risks. 1 fig., 29 refs.

  10. Development of reliability and probabilistic safety assessment program RiskA

    International Nuclear Information System (INIS)

    Wu, Yican

    2015-01-01

    Highlights: • There are four parts in the structure of RiskA. User input part lets users input the PSA model and some necessary data by GUI or model transformation tool. In calculation engine part, fault tree analysis, event tree analysis, uncertainty analysis, sensitivity analysis, importance analysis and failure mode and effects analysis are supplied. User output part outputs the analysis results, user customized reports and some other data. The last part includes reliability database, some other common tools and help documents. • RiskA has several advanced features. Extensible framework makes it easy to add any new functions, making RiskA to be a large platform of reliability and probabilistic safety assessment. It is very fast to analysis fault tree in RiskA because many advanced algorithm improvement were made. Many model formats can be imported and exported, which made the PSA model in the commercial software can be easily transformed to adapt RiskA platform. Web-based co-modeling let several users in different places work together whenever they are online. • The comparison between RiskA and other mature PSA codes (e.g. CAFTA, RiskSpectrum, XFTA) has demonstrated that the calculation and analysis of RiskA is correct and efficient. Based on the development of this code package, many applications of safety and reliability analysis of some research reactors and nuclear power plants were performed. The development of RiskA appears to be of realistic and potential value for academic research and practical operation safety management of nuclear power plants in China and abroad. - Abstract: PSA (probabilistic safety assessment) software, the indispensable tool in nuclear safety assessment, has been widely used. An integrated reliability and PSA program named RiskA has been developed by FDS Team. RiskA supplies several standard PSA modules including fault tree analysis, event tree analysis, uncertainty analysis, failure mode and effect analysis and reliability

  11. IRRAS, Integrated Reliability and Risk Analysis System for PC

    International Nuclear Information System (INIS)

    Russell, K.D.

    1995-01-01

    1 - Description of program or function: IRRAS4.16 is a program developed for the purpose of performing those functions necessary to create and analyze a complete Probabilistic Risk Assessment (PRA). This program includes functions to allow the user to create event trees and fault trees, to define accident sequences and basic event failure data, to solve system and accident sequence fault trees, to quantify cut sets, and to perform uncertainty analysis on the results. Also included in this program are features to allow the analyst to generate reports and displays that can be used to document the results of an analysis. Since this software is a very detailed technical tool, the user of this program should be familiar with PRA concepts and the methods used to perform these analyses. 2 - Method of solution: IRRAS4.16 is written entirely in MODULA-2 and uses an integrated commercial graphics package to interactively construct and edit fault trees. The fault tree solving methods used are industry recognized top down algorithms. For quantification, the program uses standard methods to propagate the failure information through the generated cut sets. 3 - Restrictions on the complexity of the problem: Due to the complexity of and the variety of ways a fault tree can be defined it is difficult to define limits on the complexity of the problem solved by this software. It is, however, capable of solving a substantial fault tree due to efficient methods. At this time, the software can efficiently solve problems as large as other software currently used on mainframe computers. Does not include source code

  12. Games for electricity traders: Understanding risk in a deregulated industry

    Energy Technology Data Exchange (ETDEWEB)

    Dyner, Isaac [Energy Institute, CeiBA-Complexity Center, Universidad Nacional de Colombia AA 1027 Medellin (Colombia)], E-mail: idyner@unalmed.edu.co; Larsen, Erik [Faculty of Economics, University of Lugano, Via Buffi 13 CH-6900 Lugano (Switzerland)], E-mail: erik.larsen@lu.unisi.ch; Franco, Carlos Jaime [Energy Institute, CeiBA-Complexity Center, Universidad Nacional de Colombia AA 1027 Medellin (Colombia)], E-mail: cjfranco@unalmed.edu.co

    2009-02-15

    We illustrate and discuss the use of a computer-based learning environment, known as a microworld, for training agents in the Colombian electricity market. As the market operator was concerned with efficiency in the electricity spot market because of an insufficient number of participants, they commissioned a tool that could help potential participants to learn about both market operation as well as the risk management it involved. By making the industry more transparent it was intended that a larger number of traders and companies would participate in the market, making it more efficient. We describe the development and use of this tool, which is based on system dynamics and gaming.

  13. Games for electricity traders. Understanding risk in a deregulated industry

    Energy Technology Data Exchange (ETDEWEB)

    Dyner, Isaac; Franco, Carlos Jaime [Energy Institute, CeiBA-Complexity Center, Universidad Nacional de Colombia AA 1027 Medellin (Colombia); Larsen, Erik [Faculty of Economics, University of Lugano, Via Buffi 13 CH-6900 Lugano (Switzerland)

    2009-02-15

    We illustrate and discuss the use of a computer-based learning environment, known as a microworld, for training agents in the Colombian electricity market. As the market operator was concerned with efficiency in the electricity spot market because of an insufficient number of participants, they commissioned a tool that could help potential participants to learn about both market operation as well as the risk management it involved. By making the industry more transparent it was intended that a larger number of traders and companies would participate in the market, making it more efficient. We describe the development and use of this tool, which is based on system dynamics and gaming. (author)

  14. Games for electricity traders. Understanding risk in a deregulated industry

    International Nuclear Information System (INIS)

    Dyner, Isaac; Franco, Carlos Jaime; Larsen, Erik

    2009-01-01

    We illustrate and discuss the use of a computer-based learning environment, known as a microworld, for training agents in the Colombian electricity market. As the market operator was concerned with efficiency in the electricity spot market because of an insufficient number of participants, they commissioned a tool that could help potential participants to learn about both market operation as well as the risk management it involved. By making the industry more transparent it was intended that a larger number of traders and companies would participate in the market, making it more efficient. We describe the development and use of this tool, which is based on system dynamics and gaming. (author)

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

    OpenAIRE

    Cioclov, Dimitru Dragos

    2013-01-01

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

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

    International Nuclear Information System (INIS)

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

    1989-01-01

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

  17. Probabilistic risk benchmark of the Brazilian electrical system; Risco probabilistico de referencia do sistema eletrico brasileiro

    Energy Technology Data Exchange (ETDEWEB)

    Soares, Neyl Hamilton Martelotta

    2002-05-01

    The main goal of this dissertation is to proceed a first numerical evaluation of the probabilistic risks magnitudes associated with the Brazilian Electrical network, considering the subsystems North, Northeast, South, Southeast and Mid West. This result is relevant because it can be used as an initial comparative reference for future reliability studies of the Brazilian Basic Grid. As a by-product, the whole set of criteria and procedures used in the work are described in detail. They may also serve as a preliminary base for future similar evaluations. (author)

  18. Risk Reduction Methods for Managing the Development of Regional Electric Power Industry

    Directory of Open Access Journals (Sweden)

    Mikhail Kozhevnikov

    2017-11-01

    Full Text Available The development of the regional electric power industry has come to the forefront due to the changing scale, quality, and configuration of electric power infrastructure, and the spread of distributed generation. This gives rise to more stringent requirements regarding the reliability, safety, and environmental impact of electric power supply. This article aims to justify a package of methods that make it possible to identify and minimize investment, production, financial, and environmental risks in order to ensure sustainable development of the regional electric power industry that performs anti-crisis functions, and of individual energy companies. The key method to be employed is integrated resource planning (IRP. As a part of the method, energy conservation, renewable energy sources, and combined heat and power production are considered as equally valid ways of meeting future demand. The authors have designed a methodology for taking into account uncertainty and risk when implementing IRP. The methodology includes analysis of scenarios and decision making processes by calculating past and projected values of profit indicators. When conducting the environmental and economic assessment of an investment project in the electric power industry, the authors suggest using an aggregate indicator of environmental and economic effectiveness that is calculated on the basis of a combination of locally significant positive and negative environmental and economic impacts of the project. The authors formulate conceptual provisions that serve as the foundation for a promising model of the regional electric power industry and which contain recommendations for managing the development of the industry while minimizing organizational, market, and technological risks.

  19. A portfolio risk analysis on electricity supply planning

    International Nuclear Information System (INIS)

    Huang, Y.-H.; Wu, J.-H.

    2008-01-01

    Conventional electricity planning selects from a range of alternative technologies based on the least-cost method without assessing cost-related risks. The current approach to determining energy generation portfolios creates a preference for fossil fuel. Consequently, this preference results in increased exposure to recent fluctuations in fossil fuel prices, particularly for countries heavily depend on imported energy. This paper applies portfolio theory in conventional electricity planning with Taiwan as a case study. The model objective is to minimize the 'risk-weighted present value of total generation cost'. Both the present value of generating cost and risk (variance of the generating cost) are considered. Risk of generating cost is introduced for volatile fuel prices and uncertainty of technological change and capital cost reduction. The impact of risk levels on the portfolio of power generation technologies is also examined to provide some valuable policy suggestions. Study results indicate that replacing fossil fuel with renewable energy helps reduce generating cost risk. However, due to limited renewable development potential in Taiwan, there is an upper bound of 15% on the maximum share of renewable energy in the generating portfolio. In the meantime, reevaluating the current nuclear energy policy for reduced exposure to fossil fuel price fluctuations is worthwhile

  20. 76 FR 10583 - Priorities for Addressing Risks to the Reliability of the Bulk-Power System; Notice Establishing...

    Science.gov (United States)

    2011-02-25

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

  1. 76 FR 2369 - Priorities for Addressing Risks to the Reliability of the Bulk-Power System; Notice of Technical...

    Science.gov (United States)

    2011-01-13

    ... Addressing Risks to the Reliability of the Bulk- Power System; Notice of Technical Conference December 16.... The purpose of the conference is to discuss policy issues related to reliability of the Bulk-Power System, including priorities for addressing risks to reliability. The agenda for this conference will be...

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

    International Nuclear Information System (INIS)

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

    1985-01-01

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

  3. Reliability of risk assessment measures used in sexually violent predator proceedings.

    Science.gov (United States)

    Miller, Cailey S; Kimonis, Eva R; Otto, Randy K; Kline, Suzonne M; Wasserman, Adam L

    2012-12-01

    The field interrater reliability of three assessment tools frequently used by mental health professionals when evaluating sex offenders' risk for reoffending--the Psychopathy Checklist-Revised (PCL-R), the Minnesota Sex Offender Screening Tool-Revised (MnSOST-R) and the Static-99-was examined within the context of sexually violent predator program proceedings. Rater agreement was highest for the Static--99 (intraclass correlation coefficient [ICC₁] = .78) and lowest for the PCL-R (ICC₁ = .60; MnSOST-R ICC₁ = .74), although all instruments demonstrated lower field reliability than that reported in their test manuals. Findings raise concerns about the reliability of risk assessment tools that are used to inform judgments of risk in high-stake sexually violent predator proceedings. Implications for future research and suggestions for improving evaluator training to increase accuracy when informing legal decision making are discussed.

  4. Relevance and reliability of experimental data in human health risk assessment of pesticides.

    Science.gov (United States)

    Kaltenhäuser, Johanna; Kneuer, Carsten; Marx-Stoelting, Philip; Niemann, Lars; Schubert, Jens; Stein, Bernd; Solecki, Roland

    2017-08-01

    Evaluation of data relevance, reliability and contribution to uncertainty is crucial in regulatory health risk assessment if robust conclusions are to be drawn. Whether a specific study is used as key study, as additional information or not accepted depends in part on the criteria according to which its relevance and reliability are judged. In addition to GLP-compliant regulatory studies following OECD Test Guidelines, data from peer-reviewed scientific literature have to be evaluated in regulatory risk assessment of pesticide active substances. Publications should be taken into account if they are of acceptable relevance and reliability. Their contribution to the overall weight of evidence is influenced by factors including test organism, study design and statistical methods, as well as test item identification, documentation and reporting of results. Various reports make recommendations for improving the quality of risk assessments and different criteria catalogues have been published to support evaluation of data relevance and reliability. Their intention was to guide transparent decision making on the integration of the respective information into the regulatory process. This article describes an approach to assess the relevance and reliability of experimental data from guideline-compliant studies as well as from non-guideline studies published in the scientific literature in the specific context of uncertainty and risk assessment of pesticides. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  5. Risk limitation, safety and environmental compatibility in electricity generation

    International Nuclear Information System (INIS)

    Angelini, A.M.

    1981-01-01

    The purpose of this paper is to present the problem of meeting future electricity needs while at the same time reducing to a minimum the risks, the pollution of air and water and the environmental effects of power stations. The first resource to exploit is the ''virtual source'' represented by energy saving pursued to the limit of the possible. The second, in order of priority, is that of renewable resources as yet unused and under development. Unfortunately, in most countries these latter resources are far from sufficient: it is then necessary to choose between the use of conventional fossil fuels and nuclear fuels. In this paper it is shown that, of all the possible fossil fuels, only coal can be considered for electricity production. As a result, in meeting new electricity needs, the choice will have to be made between coal and nuclear power. Attention is directed to factors having a significant influence on this choice, particularly the risks and safety problems in the widest sense, with a view to making a global evaluation comprising not just generating stations but the entire production cycle, from the search for the primary source to the supplying of electricity to the user. The most important problems that arise in this connection are briefly analysed in the paper, which concludes with an appeal for more objectivity in providing information on energy, such information being at present very ''polluted'' and exerting a major influence on the views of experts. (author)

  6. Financial risk management in a competitive electricity market

    International Nuclear Information System (INIS)

    Bjorgan, R.; Liu, C.C.; Lawarree, J.

    1999-01-01

    This paper proposes solutions for electricity producers in the field of financial risk management for electric energy contract evaluation. The efficient frontier is used as a tool to identify the preferred portfolio of contracts. Each portfolio has a probability density function for the profit. For important scheduling policies, closed form solutions are found for the amount of futures contracts that correspond to the efficient frontier. Production scheduling must consider resource constraints. It is found that, without resource constrains, the portfolio with the highest expected profit can be preferred--even for a risk-averse decision-maker. When resource constraints are present, portfolios not corresponding to the maximum expected profit criteria will more frequently be preferred

  7. Risk evaluation in Columbian electricity market using fuzzy logic

    International Nuclear Information System (INIS)

    Medina, S.; Moreno, J.

    2007-01-01

    This article proposes a model based on Fuzzy Logic to evaluate the market risk that a trading agent faces in the electric power negotiation in Colombia, as part of a general model of negotiation. The proposed model considers single external factors as regulatory changes, social and political issues, and the condition of the national transmission net. Variables of the market associated to these risk factors were selected and some graphic and statistical analyses were made in order to check their relationship with the electricity prices and to determine why the experts consider these factors in their analyses. According to the obtained results a Mamdani Fuzzy Inference System which contains the expert knowledge was developed and it is presented in a fuzzy cognitive map. (author)

  8. Shutdown risk management applied at Philadelphia Electric Company

    International Nuclear Information System (INIS)

    Dagan, William J.; True, Douglas E.; Wilson, Thomas; Truax, William

    2004-01-01

    The development and implementation of an effective risk management program requires basic risk or safety knowledge and the conversion of such information into effective management tools. ERIN Engineering and Research, Inc., under contract to the Electric Power Research Institute, has developed an effective program. Outage Risk Assessment and Management (ORAM), to provide plant and management personnel with understandable results of shutdown risk studies. With this tool, the impact of plans and decision options can be readily determined and displayed for the decision maker. This paper describes these methods and their application to the Limerick Nuclear Station of Philadelphia Electric Company. It also sets forth a broader application of these methods to include support of management decisions at-power and following forced outages. The result is an integrated risk management framework which can allow management and technical personnel to utilize readily available and understandable risk insights to optimize each activity. This paper addresses the resolution of several key issues in detail: How was the ORAM risk management method employed to represent the existing plant shutdown procedures and policies? How did the ORAM risk management method enhance the decision-making ability of the outage management staff? How was the ORAM software efficiently integrated with the outage scheduling software? How is quantitative risk information generated and used for outage planning and control? The ORAM risk management philosophy utilizes a series of colors to depict various risk configurations. Each such configuration has associated with it clear guidance. By modifying the conditions existing in the plant it is possible to impact the type of risk being encountered as well as the guidance which is appropriate for that period. In addition, the duration of a particular configuration can be effectively managed to reduce the overall risk impact. These are achieved with minimal

  9. Support mechanisms and risk: Implications on the Nordic electricity system

    DEFF Research Database (Denmark)

    Kitzing, Lena; Ravn, Hans

    2013-01-01

    a stochastic analysis for the Nordic electricity system by conducting simulations with the energy system model Balmorel and by applying the mean-standard deviation approach of modern portfolio theory to quantify risk implications of policy instruments for an exemplary offshore wind park. The analysis reveals......Investments in renewable energy projects, such as offshore wind parks, are very much dependent on financial support. The type of policy instrument chosen for such support determines investors' exposure to market risk, and thus influences which rate of return they expect to achieve. We make...... that the two support policy schemes Feed-in Tariffs and Feed-in Premiums provide different risk-return relationships. In the investigated case, a Feed-in Premium scheme would require a 13% higher support level, because of a 6% higher exposure of investors to market risk. Our findings can help when designing...

  10. Final Report to the National Energy Technology Laboratory on FY14- FY15 Cooperative Research with the Consortium for Electric Reliability Technology Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Vittal, Vijay [Arizona State Univ., Tempe, AZ (United States); Lampis, Anna Rosa [Arizona State Univ., Tempe, AZ (United States)

    2018-01-16

    approximately 30 principal investigators and some 70 graduate students and other researchers. Its researchers are multi-disciplinary, conducting research in three principal areas: power systems, power markets and policy, and transmission and distribution technologies. The research is collaborative; each project involves researchers typically at two universities working with industry advisors who have expressed interest in the project. Examples of topics for recent PSERC research projects include grid integration of renewables and energy storage, new tools for taking advantage of increased penetration of real-time system measurements, advanced system protection methods to maintain grid reliability, and risk and reliability assessment of increasingly complex cyber-enabled power systems. A PSERC’s objective is to proactively address the technical and policy challenges of U.S. electric power systems. To achieve this objective, PSERC works with CERTS to conduct technical research on advanced applications and investigate the design of fair and transparent electricity markets; these research topics align with CERTS research areas 1 and 2: Real-time Grid Reliability Management (Area 1), and Reliability and Markets (Area 2). The CERTS research areas overlap with the PSERC research stems: Power Systems, Power Markets, and Transmission and Distribution Technologies, as described on the PSERC website (see http://www.pserc.org/research/research_program.aspx). The performers were with Arizona State University (ASU), Cornell University (CU), University of California at Berkeley (UCB), and University of Illinois at Urbana-Champaign (UIUC). PSERC research activities in the area of reliability and markets focused on electric market and power policy analyses. The resulting studies suggest ways to frame best practices using organized markets for managing U.S. grid assets reliably and to identify highest priority areas for improvement. PSERC research activities in the area of advanced

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

    Science.gov (United States)

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

    2016-12-01

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

  12. Influence of moisture and hydrogen purity of the reliability of powerful electric machines

    International Nuclear Information System (INIS)

    Vigovs'kij, O.V.; Khvalyin, D.Yi.; Mistets'kij, V.A.

    2017-01-01

    It is shown that today the turbo generators with hydrogen-water cooling system is most unreliable technical equipment of Ukrainian nuclear power plants. On the one hand, hydrogen has several advantages over other coolers; on the other hand, the presence of hydrogen in the turbo generators systems carries the danger of engine rooms of power plants. It is also shown that the water and oxygen are main hazardous impurities in hydrogen, and zone of generator shaft compaction is the most responsible zone with high concentration of water. From the analysis was found that increasing of hydrogen purity reduces the mechanical losses and the change in total losses depending on the hydrogen purity has a linear nature. For example, with an increase the hydrogen purity from 0,1203 to 0,09 the loss in turbo generator rotor can be reduced by nearly 500 kW, which is about 25 % at a pressure of 0,5 MPa. The possibility of using metal hydrides to ensure purity, purification and hydrogen sorption was looked. The most practical value is for such hydrides as LaNi5Hx, FeTiHx, ZrNiHx. The main advantage the metal hydrides method of purification is a significant reduction in the number of purification stages. It was shown that the use of a thermoelectric gas dryer will reduce the total consumption of technological gases, that are removed from nuclear power plants, by 2,3 - 2,4 times due to a decrease in 5,0 - 6,0 times their absolute humidity, and decrease by 5, 0 times the activity of gases due to an increase in their exposure time in the decrease activity installation. All this suggests that the creation a hydrogen humidity monitoring system in the exploited turbo generator will solve the problem of objective control of hydrogen purity with further computerization and accumulation the information. Using a drainage or purification system of hydrogen, reducing the temperature and humidity of the cooling gas, can increase the reliability of operation the turbo generators and significantly

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

    Directory of Open Access Journals (Sweden)

    Leonardo Dueñas-Osorio

    2012-06-01

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

  14. 78 FR 43198 - Flexible and Local Resources Needed for Reliability in the California Wholesale Electric Market...

    Science.gov (United States)

    2013-07-19

    ... auction impact the effectiveness of forward procurement for reliability purposes? Why or why not? 11:15 a... three-year forward resource adequacy obligation backed by a market-based CAISO backstop procurement... development of a durable, market-based mechanism to provide incentives to insure reliability needs are met...

  15. Strategic bidding of generating units in competitive electricity market with considering their reliability

    International Nuclear Information System (INIS)

    Soleymani, S.; Ranjbar, A.M.; Shirani, A.R.

    2008-01-01

    In the restructured power systems, they are typically scheduled based on the offers and bids to buy and sell energy and ancillary services (AS) subject to operational and security constraints. Generally, no account is taken of unit reliability when scheduling it. Therefore generating units have no incentive to improve their reliability. This paper proposes a new method to obtain the equilibrium points for reliability and price bidding strategy of units when the unit reliability is considered in the scheduling problem. The proposed methodology employs the supply function equilibrium (SFE) for modeling a unit's bidding strategy. Units change their bidding strategies and improve their reliability until Nash equilibrium points are obtained. GAMS (general algebraic modeling system) language has been used to solve the market scheduling problem using DICOPT optimization software with mixed integer non-linear programming. (author)

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

    DEFF Research Database (Denmark)

    Edgren, Robert; Castrén, Sari; Mäkelä, Marjukka

    2016-01-01

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

  17. The Monte Carlo Simulation Method for System Reliability and Risk Analysis

    CERN Document Server

    Zio, Enrico

    2013-01-01

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

  18. High Electricity Demand in the Northeast U.S.: PJM Reliability Network and Peaking Unit Impacts on Air Quality.

    Science.gov (United States)

    Farkas, Caroline M; Moeller, Michael D; Felder, Frank A; Henderson, Barron H; Carlton, Annmarie G

    2016-08-02

    On high electricity demand days, when air quality is often poor, regional transmission organizations (RTOs), such as PJM Interconnection, ensure reliability of the grid by employing peak-use electric generating units (EGUs). These "peaking units" are exempt from some federal and state air quality rules. We identify RTO assignment and peaking unit classification for EGUs in the Eastern U.S. and estimate air quality for four emission scenarios with the Community Multiscale Air Quality (CMAQ) model during the July 2006 heat wave. Further, we population-weight ambient values as a surrogate for potential population exposure. Emissions from electricity reliability networks negatively impact air quality in their own region and in neighboring geographic areas. Monitored and controlled PJM peaking units are generally located in economically depressed areas and can contribute up to 87% of hourly maximum PM2.5 mass locally. Potential population exposure to peaking unit PM2.5 mass is highest in the model domain's most populated cities. Average daily temperature and national gross domestic product steer peaking unit heat input. Air quality planning that capitalizes on a priori knowledge of local electricity demand and economics may provide a more holistic approach to protect human health within the context of growing energy needs in a changing world.

  19. Risk management and participation planning of electric vehicles in smart grids for demand response

    International Nuclear Information System (INIS)

    Nezamoddini, Nasim; Wang, Yong

    2016-01-01

    Demand response (DR) can serve as an effective tool to better balance the electricity demand and supply in the smart grid. It is defined as 'the changes in electricity usage by end-use customers from their normal consumption patterns' in response to pricing and incentive payments. This paper focuses on new opportunities for DR with electric vehicles (EVs). EVs are potential distributed energy resources that support both the grid-to-vehicle and vehicle-to-grid modes. Their participation in the time-based (e.g., time-of-use) and incentive-based (e.g., regulation services) DR programs helps improve the stability and reduce the potential risks to the grid. Smart scheduling of EV charging and discharging activities also supports high penetration of renewables with volatile energy generation. This paper proposes a novel stochastic model from the Independent System Operator's perspective for risk management and participation planning of EVs in the smart grid for DR. The risk factors considered in this paper involve those caused by uncertainties in renewables (wind and solar), load patterns, parking patterns, and transmission lines' reliability. The effectiveness of the model in response to various settings such as the area type (residential, commercial, and industrial), the EV penetration level, and the risk level has been investigated. - Highlights: • We identify new opportunities for demand response (DR) using electric vehicles (EVs). • We integrate EVs in both grid-to-vehicle and vehicle-to-grid modes in smart grids. • EV participation for both time- and incentive-based DR programs are modelled. • We consider uncertainties in renewables, load, parking, and transmission lines. • Model case studies are demonstrated in residential, commercial, and industrial areas.

  20. reliability reliability

    African Journals Online (AJOL)

    eobe

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

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

    Science.gov (United States)

    Heinze, Cornelia; Halfens, Ruud; Dassen, Theo

    2008-12-01

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

  2. How to interpret safety critical failures in risk and reliability assessments

    International Nuclear Information System (INIS)

    Selvik, Jon Tømmerås; Signoret, Jean-Pierre

    2017-01-01

    Management of safety systems often receives high attention due to the potential for industrial accidents. In risk and reliability literature concerning such systems, and particularly concerning safety-instrumented systems, one frequently comes across the term ‘safety critical failure’. It is a term associated with the term ‘critical failure’, and it is often deduced that a safety critical failure refers to a failure occurring in a safety critical system. Although this is correct in some situations, it is not matching with for example the mathematical definition given in ISO/TR 12489:2013 on reliability modeling, where a clear distinction is made between ‘safe failures’ and ‘dangerous failures’. In this article, we show that different interpretations of the term ‘safety critical failure’ exist, and there is room for misinterpretations and misunderstandings regarding risk and reliability assessments where failure information linked to safety systems are used, and which could influence decision-making. The article gives some examples from the oil and gas industry, showing different possible interpretations of the term. In particular we discuss the link between criticality and failure. The article points in general to the importance of adequate risk communication when using the term, and gives some clarification on interpretation in risk and reliability assessments.

  3. 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...

  4. Development of component reliability data for PSA and risk based management in Japan

    International Nuclear Information System (INIS)

    Yoshihiro Tomioka; Mitsumasa Hirano; Shunsuke Kondo

    1997-01-01

    The author presents the outline of development of the component reliability data for PSA and risk based management in Japan. In the first part following the introduction, the development process is described. The next part describes issues discussed in the course of the development, which are treatment of zero failure data, error factor, estimation of unavailable failure rate and integral test

  5. 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...

  6. DJ-1 is a reliable serum biomarker for discriminating high-risk endometrial cancer.

    Science.gov (United States)

    Di Cello, Annalisa; Di Sanzo, Maddalena; Perrone, Francesca Marta; Santamaria, Gianluca; Rania, Erika; Angotti, Elvira; Venturella, Roberta; Mancuso, Serafina; Zullo, Fulvio; Cuda, Giovanni; Costanzo, Francesco

    2017-06-01

    New reliable approaches to stratify patients with endometrial cancer into risk categories are highly needed. We have recently demonstrated that DJ-1 is overexpressed in endometrial cancer, showing significantly higher levels both in serum and tissue of patients with high-risk endometrial cancer compared with low-risk endometrial cancer. In this experimental study, we further extended our observation, evaluating the role of DJ-1 as an accurate serum biomarker for high-risk endometrial cancer. A total of 101 endometrial cancer patients and 44 healthy subjects were prospectively recruited. DJ-1 serum levels were evaluated comparing cases and controls and, among endometrial cancer patients, between high- and low-risk patients. The results demonstrate that DJ-1 levels are significantly higher in cases versus controls and in high- versus low-risk patients. The receiver operating characteristic curve analysis shows that DJ-1 has a very good diagnostic accuracy in discriminating endometrial cancer patients versus controls and an excellent accuracy in distinguishing, among endometrial cancer patients, low- from high-risk cases. DJ-1 sensitivity and specificity are the highest when high- and low-risk patients are compared, reaching the value of 95% and 99%, respectively. Moreover, DJ-1 serum levels seem to be correlated with worsening of the endometrial cancer grade and histotype, making it a reliable tool in the preoperative decision-making process.

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

    International Nuclear Information System (INIS)

    Boccio, J.L.

    1986-01-01

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

  8. Risk premiums in the German day-ahead Electricity Market

    International Nuclear Information System (INIS)

    Viehmann, Johannes

    2011-01-01

    This paper conducts an empirical analysis of risk premiums in the German day-ahead Electricity Wholesale Market. We compare hourly price data of the European Energy Exchange (EEX) auction and of the continuous over-the-counter (OTC) market which takes place prior to the EEX auction. Data provided by the Energy Exchange Austria (EXAA) has been used as a snapshot of the OTC market two hours prior to the EEX auction. Ex post analysis found market participants are willing to pay both significant positive and negative premiums for hourly contracts. The largest positive premiums were paid for high demand evening peak hours on weekdays during winter months. By contrast, night hours on weekends featuring lowest demand levels display negative premiums. Additionally, ex ante analysis found a strong positive correlation between the expected tightness of the system and positive premiums. For this purpose, a tightness factor has been introduced that includes expectations of fundamental factors such as power plant availability, wind power production and demand. Hence, findings by can be supported that power traders in liberalised markets behave like risk-averse rational economic agents. - Research highlights: →Analysis of hourly risk premiums in the German day-ahead Electricity Wholesale Market. →Market participants are willing to pay both significant positive and negative premiums for hourly contracts. →A strong correlation exists between the expected tightness of the power system and premiums.

  9. Global electricity transformation: The critical need for integrated market design and risk management research

    International Nuclear Information System (INIS)

    Hung-po Chao

    2006-01-01

    The past three decades transformed the electricity industry. The essential goals of liberalization have been to lower costs, improve reliability, and stimulate investment and innovations through establishment of competitive electricity markets, while also relying on market mechanisms to provide creative solutions to environmental and security problems. In many instances, these goals have been achieved, but the occurrence of some spectacular market failures have brought into question the whole restructuring effort. This paper reviews recent experiences with market reform and concludes that a significant cause of failure has been the rush to unbundle vertically integrated utilities without sufficient consideration of alternative ways to manage the risk of electricity market restructuring. In particular, there is a critical need for integrated market design and risk management research to improve the process of market transformation by taking a more evolutionary approach to discover a 'Third Way' above vertical integration and full unbundling. Such research can offer a crucial feedback link to the restructuring process by identifying important lessons to be learned from past experience and developing new analytical tools to help introduce more successful market designs for the future. (author)

  10. 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)

  11. Evaluation of the Validity and Reliability of the Waterlow Pressure Ulcer Risk Assessment Scale.

    Science.gov (United States)

    Charalambous, Charalambos; Koulori, Agoritsa; Vasilopoulos, Aristidis; Roupa, Zoe

    2018-04-01

    Prevention is the ideal strategy to tackle the problem of pressure ulcers. Pressure ulcer risk assessment scales are one of the most pivotal measures applied to tackle the problem, much criticisms has been developed regarding the validity and reliability of these scales. To investigate the validity and reliability of the Waterlow pressure ulcer risk assessment scale. The methodology used is a narrative literature review, the bibliography was reviewed through Cinahl, Pubmed, EBSCO, Medline and Google scholar, 26 scientific articles where identified. The articles where chosen due to their direct correlation with the objective under study and their scientific relevance. The construct and face validity of the Waterlow appears adequate, but with regards to content validity changes in the category age and gender can be beneficial. The concurrent validity cannot be assessed. The predictive validity of the Waterlow is characterized by high specificity and low sensitivity. The inter-rater reliability has been demonstrated to be inadequate, this may be due to lack of clear definitions within the categories and differentiating level of knowledge between the users. Due to the limitations presented regarding the validity and reliability of the Waterlow pressure ulcer risk assessment scale, the scale should be used in conjunction with clinical assessment to provide optimum results.

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

    Science.gov (United States)

    Boes, C

    2000-12-01

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

  13. Safety, reliability, risk management and human factors: an integrated engineering approach applied to nuclear facilities

    Energy Technology Data Exchange (ETDEWEB)

    Vasconcelos, Vanderley de; Silva, Eliane Magalhaes Pereira da; Costa, Antonio Carlos Lopes da; Reis, Sergio Carneiro dos [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)], e-mail: vasconv@cdtn.br, e-mail: silvaem@cdtn.br, e-mail: aclc@cdtn.br, e-mail: reissc@cdtn.br

    2009-07-01

    Nuclear energy has an important engineering legacy to share with the conventional industry. Much of the development of the tools related to safety, reliability, risk management, and human factors are associated with nuclear plant processes, mainly because the public concern about nuclear power generation. Despite the close association between these subjects, there are some important different approaches. The reliability engineering approach uses several techniques to minimize the component failures that cause the failure of the complex systems. These techniques include, for instance, redundancy, diversity, standby sparing, safety factors, and reliability centered maintenance. On the other hand system safety is primarily concerned with hazard management, that is, the identification, evaluation and control of hazards. Rather than just look at failure rates or engineering strengths, system safety would examine the interactions among system components. The events that cause accidents may be complex combinations of component failures, faulty maintenance, design errors, human actions, or actuation of instrumentation and control. Then, system safety deals with a broader spectrum of risk management, including: ergonomics, legal requirements, quality control, public acceptance, political considerations, and many other non-technical influences. Taking care of these subjects individually can compromise the completeness of the analysis and the measures associated with both risk reduction, and safety and reliability increasing. Analyzing together the engineering systems and controls of a nuclear facility, their management systems and operational procedures, and the human factors engineering, many benefits can be realized. This paper proposes an integration of these issues based on the application of systems theory. (author)

  14. Evaluation of the Validity and Reliability of the Waterlow Pressure Ulcer Risk Assessment Scale

    Science.gov (United States)

    Charalambous, Charalambos; Koulori, Agoritsa; Vasilopoulos, Aristidis; Roupa, Zoe

    2018-01-01

    Introduction Prevention is the ideal strategy to tackle the problem of pressure ulcers. Pressure ulcer risk assessment scales are one of the most pivotal measures applied to tackle the problem, much criticisms has been developed regarding the validity and reliability of these scales. Objective To investigate the validity and reliability of the Waterlow pressure ulcer risk assessment scale. Method The methodology used is a narrative literature review, the bibliography was reviewed through Cinahl, Pubmed, EBSCO, Medline and Google scholar, 26 scientific articles where identified. The articles where chosen due to their direct correlation with the objective under study and their scientific relevance. Results The construct and face validity of the Waterlow appears adequate, but with regards to content validity changes in the category age and gender can be beneficial. The concurrent validity cannot be assessed. The predictive validity of the Waterlow is characterized by high specificity and low sensitivity. The inter-rater reliability has been demonstrated to be inadequate, this may be due to lack of clear definitions within the categories and differentiating level of knowledge between the users. Conclusion Due to the limitations presented regarding the validity and reliability of the Waterlow pressure ulcer risk assessment scale, the scale should be used in conjunction with clinical assessment to provide optimum results. PMID:29736104

  15. Safety, reliability, risk management and human factors: an integrated engineering approach applied to nuclear facilities

    International Nuclear Information System (INIS)

    Vasconcelos, Vanderley de; Silva, Eliane Magalhaes Pereira da; Costa, Antonio Carlos Lopes da; Reis, Sergio Carneiro dos

    2009-01-01

    Nuclear energy has an important engineering legacy to share with the conventional industry. Much of the development of the tools related to safety, reliability, risk management, and human factors are associated with nuclear plant processes, mainly because the public concern about nuclear power generation. Despite the close association between these subjects, there are some important different approaches. The reliability engineering approach uses several techniques to minimize the component failures that cause the failure of the complex systems. These techniques include, for instance, redundancy, diversity, standby sparing, safety factors, and reliability centered maintenance. On the other hand system safety is primarily concerned with hazard management, that is, the identification, evaluation and control of hazards. Rather than just look at failure rates or engineering strengths, system safety would examine the interactions among system components. The events that cause accidents may be complex combinations of component failures, faulty maintenance, design errors, human actions, or actuation of instrumentation and control. Then, system safety deals with a broader spectrum of risk management, including: ergonomics, legal requirements, quality control, public acceptance, political considerations, and many other non-technical influences. Taking care of these subjects individually can compromise the completeness of the analysis and the measures associated with both risk reduction, and safety and reliability increasing. Analyzing together the engineering systems and controls of a nuclear facility, their management systems and operational procedures, and the human factors engineering, many benefits can be realized. This paper proposes an integration of these issues based on the application of systems theory. (author)

  16. Nuclear power plants electrical retrofitting for cost effectiveness, reliability and operating efficiency

    International Nuclear Information System (INIS)

    Ciufu, L.; Popescu, M. O.

    2016-01-01

    In the context of continuous fast growing of the energy demand the current power plants retrofitting concept may represent an important step in the emission reduction, being able to offer in the same time a maximum operating efficiency. This desideratum can be obtained by implementing a rigorous energy management plan, based on an increased energy production capacity of non-pollutant electrical power plants and future-oriented frame on extending their lifetime operation. This management is focused on using state-of-art electronic, electrical and industrial control equipments, which can represent a real key factor. Thus, in this paper an analysis of the electrical system retrofitting is presented. As a part of this research the authors propose and simulate ambitious ways to upgrade actual control and command of the electrical operating systems, by promoting variable speed for large pumps and also computer software, as SCADA, for an intelligent control and monitoring of these studied processes. (authors)

  17. The safety and reliability of the electricity transportation network, and the opening of markets

    International Nuclear Information System (INIS)

    Merlin, A.

    2003-01-01

    Following a decade in which the electricity sector was concerned by the opening of markets the world over, the year 2003 highlighted the challenges of secure supply and of the safety of electrical systems. Major incidents are nothing new throughout history, and occurred well before the trend towards opening the markets dot underway. However, it is necessary to verify that the rules for the organisation, clarification of responsibilities and regulation make it possible to control the growing complexity of interconnected systems related to opening the market up to competition. Faced with such situations, changes are necessary in Europe. Firstly, it is important to have the second European directive on the internal electricity market introduced everywhere, this directive providing common rules to be met by all key players to ensure greater safety within the electricity system, and strengthening the role of the electricity transport network manager, who is separate from the other players in the market. It is also necessary to draft a third directive, focusing on both security of supply and the operational safety of the European electricity system. (authors)

  18. WHO's health risk assessment of extremely low frequency electric fields

    International Nuclear Information System (INIS)

    Repacholi, M.H.

    2003-01-01

    The World Health Organization (WHO), the International Commission on Non-Ionizing Radiation Protection (ICNIRP), WHOs scientific collaborating centres (including the UKs National Radiological Protection Board (NRPB) and over 50 participating Member States are participants of WHOs International EMF Project. As part of WHOs health risk assessment process for extremely low frequency fields (ELFs), this workshop was convened by NRPB to assist WHO in evaluating potential health impacts of electrical currents and fields induced by ELF in molecules, cells, tissues and organs of the body. This paper describes the process by which WHO will conduct its health risk assessment. WHO is also trying to provide information on why exposure to ELF magnetic fields seems to be associated with an increased incidence of childhood leukaemia. Are there mechanisms that could lead to this health outcome or does the epidemiological evidence incorporate biases or other factors that need to be further explored? (author)

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

    International Nuclear Information System (INIS)

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

    1990-01-01

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

  20. A reliability-risk modelling of nuclear rad-waste facilities

    International Nuclear Information System (INIS)

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

    1975-01-01

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

  1. Risk analysis of the LHC underground area fire risk due to faulty electrical equipment

    CERN Document Server

    Harrison, A

    2007-01-01

    The European Organisation for Nuclear Research (CERN) in Geneva, Switzerland, is currently building the latest generation of particle accelerators, the LHC (Large Hadron Collider). The machine is housed in a circular tunnel of 27 km of circumference and is situated approximately 100 metres beneath the surface astride the Franco-Swiss border. Electrically induced fires in the LHC are a major concern, since an incident could present a threat to CERN personnel as well as the public. Moreover, the loss of equipment would result in significant costs and downtime. However, the amount of electrical equipment in the underground area required for operation, supervision and control of the machine is essential. Thus the present thesis is assessing the risk of fire due to faulty electrical equipment in both a qualitative as well as quantitative way. The recommendations following the qualitative analysis suggest the introduction of fire protection zones for the areas with the highest risk of fire due to a combination of p...

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

    International Nuclear Information System (INIS)

    Berning, A.; Spindler, H.

    1983-01-01

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

  3. Space Station Freedom power - A reliability, availability, and maintainability assessment of the proposed Space Station Freedom electric power system

    Science.gov (United States)

    Turnquist, S. R.; Twombly, M.; Hoffman, D.

    1989-01-01

    A preliminary reliability, availability, and maintainability (RAM) analysis of the proposed Space Station Freedom electric power system (EPS) was performed using the unit reliability, availability, and maintainability (UNIRAM) analysis methodology. Orbital replacement units (ORUs) having the most significant impact on EPS availability measures were identified. Also, the sensitivity of the EPS to variations in ORU RAM data was evaluated for each ORU. Estimates were made of average EPS power output levels and availability of power to the core area of the space station. The results of assessments of the availability of EPS power and power to load distribution points in the space stations are given. Some highlights of continuing studies being performed to understand EPS availability considerations are presented.

  4. Generic risk insights for General Electric boiling water reactors

    International Nuclear Information System (INIS)

    Travis, R.; Taylor, J.; Chung, J.

    1991-05-01

    A methodology has been developed to extract generic risk-based information from probabilistic risk assessments (PRAs) of General Electric boiling water rectors and applying the insights gained to plants that have not been subjected to a PRA. The available risk assessments (six plants) were examined to identify the most probable, i.e., dominant accident sequences at each plants. The goal was to include all sequences which represented at least 80% of core damage frequency. If the same plant specific dominant accident sequence appeared within this boundary in at least two plant PRAs, the sequence was considered to be a representative sequence. Eight sequences met this definition. From these sequences, the most important component failures and human error that contributed to each sequence have been prioritized. Guidance is provided to prioritize the representative sequences and modify selected basic events that have been shown to be sensitive to the plant specific design or operating variations of the contributing PRAs. This risk-based guidance can be used for utility and NRC activities including operator training, maintenance, design review, and inspections. 13 refs., 6 tabs

  5. Electricity distribution. Price control, reliability and customer services: response to OFFER

    International Nuclear Information System (INIS)

    1994-02-01

    This document presents the views of the National Consumer Council to a recent consultation paper from OFFER, the body responsible for regulation of the United Kingdom electric power industry. The financial performance of the Regional Electricity Companies (RECs) is reviewed by examining how it relates to the prices paid by domestic consumers. A critical analysis is presented of OFFER's notion of the revision of the existing price control mechanism for the distribution businesses within the RECs. Standards of performance, debt and consumer disconnection are also examined. (UK)

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

    Science.gov (United States)

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

    2017-11-01

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

  7. Accelerated reliability testing of highly aligned single-walled carbon nanotube networks subjected to DC electrical stressing.

    Science.gov (United States)

    Strus, Mark C; Chiaramonti, Ann N; Kim, Young Lae; Jung, Yung Joon; Keller, Robert R

    2011-07-01

    We investigate the electrical reliability of nanoscale lines of highly aligned, networked, metallic/semiconducting single-walled carbon nanotubes (SWCNTs) fabricated through a template-based fluidic assembly process. We find that these SWCNT networks can withstand DC current densities larger than 10 MA cm(-2) for several hours and, in some cases, several days. We develop test methods that show that the degradation rate, failure predictability and total device lifetime can be linked to the initial resistance. Scanning electron and transmission electron microscopy suggest that fabrication variability plays a critical role in the rate of degradation, and we offer an empirical method of quickly determining the long-term performance of a network. We find that well-fabricated lines subject to constant electrical stress show a linear accumulation of damage reminiscent of electromigration in metallic interconnects, and we explore the underlying physical mechanisms that could cause such behavior.

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

    Directory of Open Access Journals (Sweden)

    Marco Aurelio Lumertz Saffi

    2013-10-01

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

  9. Novel Threat-risk Index Using Probabilistic Risk Assessment and Human Reliability Analysis - Final Report

    Energy Technology Data Exchange (ETDEWEB)

    George A. Beitel

    2004-02-01

    In support of a national need to improve the current state-of-the-art in alerting decision makers to the risk of terrorist attack, a quantitative approach employing scientific and engineering concepts to develop a threat-risk index was undertaken at the Idaho National Engineering and Environmental Laboratory (INEEL). As a result of this effort, a set of models has been successfully integrated into a single comprehensive model known as Quantitative Threat-Risk Index Model (QTRIM), with the capability of computing a quantitative threat-risk index on a system level, as well as for the major components of the system. Such a threat-risk index could provide a quantitative variant or basis for either prioritizing security upgrades or updating the current qualitative national color-coded terrorist threat alert.

  10. Analyse Risk-Return Paradox: Evidence from Electricity Sector of Pakistan

    OpenAIRE

    Naqi Shah, Sadia; Qayyum, Abdul

    2016-01-01

    This study analyse risk return relationship of the electricity companies of Pakistan by using the log return series of these electricity companies. Financial time series data have the property of autoregressive heteroscedasticity so move towards the GARCH family test. As the study want to analyse the risk return relationship so, GARCH-M Model of Engel et al (1987) is used, who empirically found relationship between risk and return. Results show that risk return in case of Pakistan electricity...

  11. An evaluation of the reliability and usefulness of external-initiator PRA [probabilistic risk analysis] methodologies

    International Nuclear Information System (INIS)

    Budnitz, R.J.; Lambert, H.E.

    1990-01-01

    The discipline of probabilistic risk analysis (PRA) has become so mature in recent years that it is now being used routinely to assist decision-making throughout the nuclear industry. This includes decision-making that affects design, construction, operation, maintenance, and regulation. Unfortunately, not all sub-areas within the larger discipline of PRA are equally ''mature,'' and therefore the many different types of engineering insights from PRA are not all equally reliable. 93 refs., 4 figs., 1 tab

  12. Reliability and risk functions for structural components taking into account inspection results

    International Nuclear Information System (INIS)

    Rackwitz, R.; Schall, G.

    1989-01-01

    The method of outcrossings has been shown to be efficient when calculating the failure probability of metallic structural components under ergodic Gaussian loading. Using Paris/Erdogan's crack growth law it is possible to develop a semi-analytical calculation model for both the reliability and the risk function. For numerical studies an approximate method of asymptotic nature is proposed. The same methodology also enables to incorporate inspection observations. (orig.) [de

  13. An evaluation of the reliability and usefulness of external-initiator PRA (probabilistic risk analysis) methodologies

    Energy Technology Data Exchange (ETDEWEB)

    Budnitz, R.J.; Lambert, H.E. (Future Resources Associates, Inc., Berkeley, CA (USA))

    1990-01-01

    The discipline of probabilistic risk analysis (PRA) has become so mature in recent years that it is now being used routinely to assist decision-making throughout the nuclear industry. This includes decision-making that affects design, construction, operation, maintenance, and regulation. Unfortunately, not all sub-areas within the larger discipline of PRA are equally mature,'' and therefore the many different types of engineering insights from PRA are not all equally reliable. 93 refs., 4 figs., 1 tab.

  14. A Study on the Thermomechanical Reliability Risks of Through-Silicon-Vias in Sensor Applications

    Directory of Open Access Journals (Sweden)

    Shuai Shao

    2017-02-01

    Full Text Available Reliability risks for two different types of through-silicon-vias (TSVs are discussed in this paper. The first is a partially-filled copper TSV, if which the copper layer covers the side walls and bottom. A polymer is used to fill the rest of the cavity. Stresses in risk sites are studied and ranked for this TSV structure by FEA modeling. Parametric studies for material properties (modulus and thermal expansion of TSV polymer are performed. The second type is a high aspect ratio TSV filled by polycrystalline silicon (poly Si. Potential risks of the voids in the poly Si due to filling defects are studied. Fracture mechanics methods are utilized to evaluate the risk for two different assembly conditions: package assembled to printed circuit board (PCB and package assembled to flexible substrate. The effect of board/substrate/die thickness and the size and location of the void are discussed.

  15. Preparing for climate change regulation : an assessment of the current state of date reliability in the Canadian electrical industry

    International Nuclear Information System (INIS)

    Schuh, C.

    2003-01-01

    This presentation provided an overview of current Canadian greenhouse gas (GHG) reporting requirements, predictions about GHG regulations, and the current state of GHGs data reliability in the Canadian electrical industry. The author argued that while potential management strategies are necessary, they are not sufficient to meet Kyoto or similar types of initiatives because they do not provide incentives for reductions, they do not establish accountability, nor do they encourage reliable data. It was predicted that the first climate change regulation will be a sectoral agreement enacted at the federal/provincial level. It was also predicted that future regulations will include a requirement to report GHG emissions in a reliable manner and that regulators will use the data to track performance. The final prediction was that the onus will be on the companies to prove that the data is reliable as regulators will have limited resources to check the data. It was noted that the current state of data is not suitable for analytical testing because of a lack of clear definitions, a lack of industry comparison, inability to compare between companies, inability to compare between different types of power generation, and the inability to compare between years. It was suggested that data reliability could be improved by having the regulators review and monitor the reported data, or by having a third party review and provide assurance on the reported data. It was concluded that there will have to be agreement at the industry level on common measurement and calculation methodology, as well as an agreement on a common scope of reporting. 4 figs

  16. Fuel cells and electricity companies - new risk management opportunities

    International Nuclear Information System (INIS)

    Whale, M.

    2004-01-01

    'Full text:' Deregulation, distributed generation, combined heat and power, renewables, fuel cells, hydrogen. Power companies are facing a rapidly evolving environment that is testing their ability to effectively deploy capital and earn profits. While recent deregulation trends have shifted the structure of power markets into separating generators from distributors, the improving economic value proposition offered by smaller scale distributed generation technologies - such as fuel cells - would seem to be a conflicting development. In this complex and changing environment, decisions based on the economic reality of the capital markets are likely to prevail. By examining the opportunity to enhance risk management offered by stationary fuel cells, particularly in CHP applications, we provide a context for the issues being discussed in today's sessions focusing on power companies and electric utilities. Our risk management perspective suggests a pathway for implementing fuel cells in combined heat and power applications that large power generators can introduce in increasingly smaller sizes. With capital costs of fuel cells high and risk tolerance of power companies low, the challenge for smaller technology developers will be to reduce the apparently long time horizon that persists for substantial deployment. (author)

  17. Seismic risk analysis for the Westinghouse Electric facility, Cheswick, Pennsylvania

    International Nuclear Information System (INIS)

    1977-01-01

    This report presents the results of a detailed seismic risk analysis of the Westinghouse Electric plutonium fuel development facility at Cheswick, Pennsylvania. This report focuses on earthquakes. The historical seismic record was established after a review of available literature, consultation with operators of local seismic arrays and examination of appropriate seismic data bases. Because of the aseismicity of the region around the site, an analysis different from the conventional closest approach in a tectonic province was adapted. Earthquakes as far from the site as 1,000 km were included, as were the possibility of earthquakes at the site. In addition, various uncertainties in the input were explicitly considered in the analysis. For example, allowance was made for both the uncertainty in predicting maximum possible earthquakes in the region and the effect of the dispersion of data about the best fit attenuation relation. The attenuation relationship is derived from two of the most recent, advanced studies relating earthquake intensity reports and acceleration. Results of the risk analysis, which include a Bayesian estimate of the uncertainties, are presented as return period accelerations. The best estimate curve indicates that the Westinghouse facility will experience 0.05 g every 220 years and 0.10 g every 1400 years. The accelerations are very insensitive to the details of the source region geometries or the historical earthquake statistics in each region and each of the source regions contributes almost equally to the cumulative risk at the site

  18. Competitive electric power markets and grid reliability : something has changed during the past decade

    International Nuclear Information System (INIS)

    Fluckiger, K.

    2005-01-01

    This white paper reviewed some of the fundamental changes in the way in which electricity is provided to customers. Previously, electricity was delivered by integrated electric utilities that owned both generation and transmission and directly served their customers. Restructuring altered the rules that govern control, operation, ownership and regulation of the industry. The traditional integrated utility has been disaggregated. Wholesale electricity costs are no longer regulated and prices are now set by supply and demand in a market context. Generation investment decisions are based on future expectations of market performance. It was suggested that transmission should become a facilitator of the competitive market. Inter-ties are an essential part of a competitive market, as a means to import power when needed and to export surplus energy. The role of transmission in facilitating new generation by providing non-discriminatory and efficient transport to the market was discussed. It was noted that the lack of transmission investment is resulting in economic penalties, rising losses and constraints on more economic generators. Transmission congestion is counterproductive to the interests of customers. A move away from regional planning to a recognition of the wider interconnectedness of the system was recommended. The current practice of deferring necessary maintenance as a way to generate short-term profit was examined. It was noted that despite the need for new transmission infrastructure, investment in merchant alternating current projects has been slow to materialize. Other challenges to transmission included the uncertainty of regulatory processes and investment recovery as well as the unpredictability of flow patterns in the bulk power system. It was concluded that competitive generation markets will not work with an inadequate transmission infrastructure. Transmission enables new generation by ensuring non-discriminatory and efficient transport to market

  19. RELIABILITY ANALYSIS OF THE ELECTRICAL POWER DISTRIBUTION SYSTEM TO SELECTED PORTIONS OF THE NUCLEAR HVAC SYSTEM

    International Nuclear Information System (INIS)

    Ramirez, N.

    2004-01-01

    A design requirement probability of 0.01 or less in a 4-hour period ensures that the nuclear heating, ventilation, and air-conditioning (HVAC) system in the primary confinement areas of the Dry Transfer Facilities (DTFs) and Fuel Handling Facility (FHF) is working during a Category 1 drop event involving commercial spent nuclear fuel (CSNF) assemblies (BSC 2004a , Section 5.1.1.48). This corresponds to an hourly HVAC failure rate of 2.5E-3 per hour or less, which is contributed to by two dominant causes: equipment failure and loss of electrical power. Meeting this minimum threshold ensures that a Category 1 initiating event followed by the failure of HVAC is a Category 2 event sequence. The two causes for the loss of electrical power include the loss of offsite power and the loss of onsite power distribution. Thus, in order to meet the threshold requirement aforementioned, the failure rate of mechanical equipment, loss of offsite power, and loss of onsite power distribution must be less than or equal to 2.5E-3 per hour for the nuclear HVAC system in the primary confinement areas of the DTFs and FHF. The loss of offsite power occurs at a frequency of 1.1E-5 per hour (BSC 2004a, Section 5.1.1.48). The purpose of this analysis is to determine the probability of occurrence of the unavailability of the nuclear HVAC system in the primary confinement areas of the DTFs and FHF due to loss of electrical power. In addition, this analysis provides insights on the contribution to the unavailability of the HVAC system due to equipment failure. The scope of this analysis is limited to finding the frequency of loss of electrical power to the nuclear HVAC system in the primary confinement areas of the DTFs and FHF

  20. Competing risk models in reliability systems, a Weibull distribution model with Bayesian analysis approach

    International Nuclear Information System (INIS)

    Iskandar, Ismed; Gondokaryono, Yudi Satria

    2016-01-01

    In reliability theory, the most important problem is to determine the reliability of a complex system from the reliability of its components. The weakness of most reliability theories is that the systems are described and explained as simply functioning or failed. In many real situations, the failures may be from many causes depending upon the age and the environment of the system and its components. Another problem in reliability theory is one of estimating the parameters of the assumed failure models. The estimation may be based on data collected over censored or uncensored life tests. In many reliability problems, the failure data are simply quantitatively inadequate, especially in engineering design and maintenance system. The Bayesian analyses are more beneficial than the classical one in such cases. The Bayesian estimation analyses allow us to combine past knowledge or experience in the form of an apriori distribution with life test data to make inferences of the parameter of interest. In this paper, we have investigated the application of the Bayesian estimation analyses to competing risk systems. The cases are limited to the models with independent causes of failure by using the Weibull distribution as our model. A simulation is conducted for this distribution with the objectives of verifying the models and the estimators and investigating the performance of the estimators for varying sample size. The simulation data are analyzed by using Bayesian and the maximum likelihood analyses. The simulation results show that the change of the true of parameter relatively to another will change the value of standard deviation in an opposite direction. For a perfect information on the prior distribution, the estimation methods of the Bayesian analyses are better than those of the maximum likelihood. The sensitivity analyses show some amount of sensitivity over the shifts of the prior locations. They also show the robustness of the Bayesian analysis within the range

  1. Risk assessment of electric generation systems with high wind penetration

    International Nuclear Information System (INIS)

    Salgado Duarte, Yorlandys; Castillo Serpa, Alfredo M. del

    2017-01-01

    The research evaluates the risk function of an Electric Generation System (SGE) with high wind power penetration using the Sequential Monte Carlo Simulation (SMCS) method, which allows calculating indicators that characterize the performance of the SGE with expected average values. The research uses a Markov model of two states or four states according to the characteristics of the generator to simulate the instantaneous capacity. The primary sources of each conventional generator are assumed to be always available; however, wind power depends on the wind behavior in each analyzed region. In this research, the Chronological Series and Weibull models are used to model the wind behavior, and the analyzes are performed in the IEEE-RTS system. The work shows that the behavior of the probabilistic indicators used to analyze the static capacity of the SGE is determined by the model used to simulate the stochastic of the generators and by the primary energy source. (author)

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

    Science.gov (United States)

    Ghaffarian, Reza; Evans, John W.

    2014-01-01

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

  3. Holomorphic Embedding for Loadflow Integration of Operational Thermal and Electric Reliable Procedural Systems, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This sound, low risk proposal aims at developing technology for the fundamental modeling and data processing needs of future autonomous operation. It addresses...

  4. Environmental and Economic Optimization Model for Electric System Planning in Ningxia, China: Inexact Stochastic Risk-Aversion Programming Approach

    Directory of Open Access Journals (Sweden)

    L. Ji

    2015-01-01

    Full Text Available The main goal of this paper is to provide a novel risk aversion model for long-term electric power system planning from the manager’s perspective with the consideration of various uncertainties. In the proposed method, interval parameter programming and two-stage stochastic programming are integrated to deal with the technical, economics, and policy uncertainties. Moreover, downside risk theory is introduced to balance the trade-off between the profit and risk according to the decision-maker’s risk aversion attitude. To verify the effectiveness and practical application of this approach, an inexact stochastic risk aversion model is developed for regional electric system planning and management in Ningxia Hui Autonomous Region, China. The series of solutions provide the decision-maker with the optimal investment strategy and operation management under different future emission reduction scenarios and risk-aversion levels. The results indicated that pollution control devices are still the main measures to achieve the current mitigation goal and the adjustment of generation structure would play an important role in the future cleaner electricity system with the stricter environmental policy. In addition, the model can be used for generating decision alternatives and helping decision-makers identify desired energy structure adjustment and pollutants/carbon mitigation abatement policies under various economic and system-reliability constraints.

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

    Science.gov (United States)

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

    2016-08-01

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

  6. A competing risk model for the reliability of cylinder liners in marine Diesel engines

    Energy Technology Data Exchange (ETDEWEB)

    Bocchetti, D. [Grimaldi Group, Naples (Italy); Giorgio, M. [Department of Aerospace and Mechanical Engineering, Second University of Naples, Aversa (Italy); Guida, M. [Department of Information Engineering and Electrical Engineering, University of Salerno, Fisciano (Italy); Pulcini, G. [Istituto Motori, National Research Council-CNR, Naples (Italy)], E-mail: g.pulcini@im.cnr.it

    2009-08-15

    In this paper, a competing risk model is proposed to describe the reliability of the cylinder liners of a marine Diesel engine. Cylinder liners presents two dominant failure modes: wear degradation and thermal cracking. The wear process is described through a stochastic process, whereas the failure time due to the thermal cracking is described by the Weibull distribution. The use of the proposed model allows performing goodness-of-fit test and parameters estimation on the basis of both wear and failure data. Moreover, it enables reliability estimates of the state of the liners to be obtained and the hierarchy of the failure mechanisms to be determined for any given age and wear level of the liner. The model has been applied to a real data set: 33 cylinder liners of Sulzer RTA 58 engines, which equip twin ships of the Grimaldi Group. Estimates of the liner reliability and of other quantities of interest under the competing risk model are obtained, as well as the conditional failure probability and mean residual lifetime, given the survival age and the accumulated wear. Furthermore, the model has been used to estimate the probability that a liner fails due to one of the failure modes when both of these modes act.

  7. Development of reliability databases and the particular requirements of probabilistic risk analyses

    International Nuclear Information System (INIS)

    Meslin, T.

    1989-01-01

    Nuclear utilities have an increasing need to develop reliability databases for their operating experience. The purposes of these databases are often multiple, including both equipment maintenance aspects and probabilistic risk analyses. EDF has therefore been developing experience feedback databases, including the Reliability Data Recording System (SRDF) and the Event File, as well as the history of numerous operating documents. Furthermore, since the end of 1985, EDF has been preparing a probabilistic safety analysis applied to one 1,300 MWe unit, for which a large amount of data of French origin is necessary. This data concerns both component reliability parameters and initiating event frequencies. The study has thus been an opportunity for trying out the performance databases for a specific application, as well as in-depth audits of a number of nuclear sites to make it possible to validate numerous results. Computer aided data collection is also on trial in a number of plants. After describing the EDF operating experience feedback files, we discuss the particular requirements of probabilistic risk analyses, and the resources implemented by EDF to satisfy them. (author). 5 refs

  8. Integrating software reliability concepts into risk and reliability modeling of digital instrumentation and control systems used in nuclear power plants

    International Nuclear Information System (INIS)

    Arndt, S. A.

    2006-01-01

    As software-based digital systems are becoming more and more common in all aspects of industrial process control, including the nuclear power industry, it is vital that the current state of the art in quality, reliability, and safety analysis be advanced to support the quantitative review of these systems. Several research groups throughout the world are working on the development and assessment of software-based digital system reliability methods and their applications in the nuclear power, aerospace, transportation, and defense industries. However, these groups are hampered by the fact that software experts and probabilistic safety assessment experts view reliability engineering very differently. This paper discusses the characteristics of a common vocabulary and modeling framework. (authors)

  9. The effect of plant reliability improvement in the cost of generating electricity

    International Nuclear Information System (INIS)

    Nejat, S.; Sanders, R.C.; Tsoulfanidis, N.

    1982-01-01

    The objective of this investigation is to study the economic benefits in operating a nuclear power plant, as a result of improving the availability of the secondary (steam) loop of the plant. A new method has been developed to obtain availability, frequency of failure, probability and frequency of operation, cycle time, and uptime for different capacity states of a parallel series system having components with failure and repair rates distributed exponentially in time. The method has been applied to different subsystems, systems, and the secondary loop of a plant as a whole. The effect of having spare parts for several components, as measured by savings in the generation of electricity, is also studied. The Kettelle algorithm was applied to determine optimal allocation of spare parts to achieve maximum availability or minimum cost of electricity, subject to a fixed spare parts budget. The savings per year for optimal spare parts allocation and different spare parts budgets were obtained. The results show that the utility will save its customers a large amount of money if spare parts are purchased, especially at the beginning of the plant operation, and are allocated judiciously

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

    Science.gov (United States)

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

    2009-07-01

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

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

    LENUS (Irish Health Repository)

    Walsh, Breda

    2012-02-01

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

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

    LENUS (Irish Health Repository)

    Walsh, Breda

    2011-05-01

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

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

    Science.gov (United States)

    Wyss, Gregory D.

    2000-01-01

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

  14. The risk of nuclear power in Germany compared with the risk other electricity generating technologies

    International Nuclear Information System (INIS)

    Preiss, P.; Wissel, S.; Fahl, U.; Friedrich, R.; Voss, A.

    2013-01-01

    The report shows that no electricity generation technology is without risk and without environmental impact. Taking into account the quantifiable risks of loss expenses in case of accidents the study shows that the health hazards and economical risk are by trend about equal for nuclear power and renewable energy sources. The study is based on the statement that the severe accident in Fukushima-Daiichi cannot be ascribed to so-called remaining risk since the NPP was not designed for tsunamis of the size that occurred in 2011 although this size was of high probability and that the calculated very low probabilities for severe accidents in German nuclear power plants correspond to the reality.

  15. The impact of faulty response of overload protection systems on the reliability of electricity supply

    International Nuclear Information System (INIS)

    Schweigert, J.; Schnuerer, G.

    1988-01-01

    Protection equipment of the engineered safety system which is to prevent the triggering of actions via signals from the reactor protection system is to be made so reliable that it has no impact on the non-availability of the supplied systems. Design and functional mode of the various overload protection equipment and the relevant switching device and combinations are explained together with the requirements such as choice, design, and adjustment of the protection equipment, followed by a survey of possible causes of faulty response of overload protection device and of the means and measures available for improvement. The now presented version of September 1987 of the 'overload protection report deals basically with all main topics of the Juli 1985 version, but has been updated and extended by material taking into account practice-oriented data on the new developments in convoy power plant design. (orig./HP) [de

  16. 76 FR 7187 - Priorities for Addressing Risks to the Reliability of the Bulk-Power System; Reliability...

    Science.gov (United States)

    2011-02-09

    ..., U.S. House of Representatives. 10:35 a.m. Introductions; Commissioner Cheryl LaFleur, Chair. 10:40 a... protecting against sophisticated and fast-moving threats? What role do you expect Smart Grid to play in the... grid reliability under Smart Grid applications? If not, how should NERC address these issues? c. Will...

  17. Risk management in the electric power sector, v. 16(61)

    International Nuclear Information System (INIS)

    Iliev, Atanas; Minovski, Dragan

    2008-01-01

    This paper presents the basics of the risk theory and the main methods which could be applied for risk management in electrical power system utilities. Taking into consideration that the risk and uncertainty not be completely eliminated, the engineers have to know to manage the risk and uncertainty. The main goal is to minimized the negative effects from accepted risk in order to increase expected incomes and expected profit. Special attention is dedicated to risk management in complex project in Electric Power Systems in a new deregulated electricity market which has the influence to the market stability, expected incomes and quality of the delivered electricity. Specially, the risk management in the companies - producers of the electricity is analysed, since theirs further investments in a rehabilitation of the current power plants as well in the construction of the new plants will be based on the economical principles of profit. (Author)

  18. Risk management in the electric power sector, v. 16(62)

    International Nuclear Information System (INIS)

    Iliev, Atanas; Minovski, Dragan

    2008-01-01

    This paper presents the basics of the risk theory and the main methods which could be applied for risk management in electrical power system utilities. Taking into consideration that the risk and uncertainty not be completely eliminated, the engineers have to know to manage the risk and uncertainty. The main goal is to minimized the negative effects from accepted risk in order to increase expected incomes and expected profit. Special attention is dedicated to risk management in complex project in Electric Power Systems in a new deregulated electricity market which has the influence to the market stability, expected incomes and quality of the delivered electricity. Specially, the risk management in the companies - producers of the electricity is analysed, since theirs further investments in a rehabilitation of the current power plants as well in the construction of the new plants will be based on the economical principles of profit. (Author)

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

    Science.gov (United States)

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

    2009-01-01

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

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

    Directory of Open Access Journals (Sweden)

    hadi hojati

    2018-04-01

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

  1. Mobile phone radiation health risk controversy: the reliability and sufficiency of science behind the safety standards.

    Science.gov (United States)

    Leszczynski, Dariusz; Xu, Zhengping

    2010-01-27

    There is ongoing discussion whether the mobile phone radiation causes any health effects. The International Commission on Non-Ionizing Radiation Protection, the International Committee on Electromagnetic Safety and the World Health Organization are assuring that there is no proven health risk and that the present safety limits protect all mobile phone users. However, based on the available scientific evidence, the situation is not as clear. The majority of the evidence comes from in vitro laboratory studies and is of very limited use for determining health risk. Animal toxicology studies are inadequate because it is not possible to "overdose" microwave radiation, as it is done with chemical agents, due to simultaneous induction of heating side-effects. There is a lack of human volunteer studies that would, in unbiased way, demonstrate whether human body responds at all to mobile phone radiation. Finally, the epidemiological evidence is insufficient due to, among others, selection and misclassification bias and the low sensitivity of this approach in detection of health risk within the population. This indicates that the presently available scientific evidence is insufficient to prove reliability of the current safety standards. Therefore, we recommend to use precaution when dealing with mobile phones and, whenever possible and feasible, to limit body exposure to this radiation. Continuation of the research on mobile phone radiation effects is needed in order to improve the basis and the reliability of the safety standards.

  2. Mobile phone radiation health risk controversy: the reliability and sufficiency of science behind the safety standards

    Directory of Open Access Journals (Sweden)

    Leszczynski Dariusz

    2010-01-01

    Full Text Available Abstract There is ongoing discussion whether the mobile phone radiation causes any health effects. The International Commission on Non-Ionizing Radiation Protection, the International Committee on Electromagnetic Safety and the World Health Organization are assuring that there is no proven health risk and that the present safety limits protect all mobile phone users. However, based on the available scientific evidence, the situation is not as clear. The majority of the evidence comes from in vitro laboratory studies and is of very limited use for determining health risk. Animal toxicology studies are inadequate because it is not possible to "overdose" microwave radiation, as it is done with chemical agents, due to simultaneous induction of heating side-effects. There is a lack of human volunteer studies that would, in unbiased way, demonstrate whether human body responds at all to mobile phone radiation. Finally, the epidemiological evidence is insufficient due to, among others, selection and misclassification bias and the low sensitivity of this approach in detection of health risk within the population. This indicates that the presently available scientific evidence is insufficient to prove reliability of the current safety standards. Therefore, we recommend to use precaution when dealing with mobile phones and, whenever possible and feasible, to limit body exposure to this radiation. Continuation of the research on mobile phone radiation effects is needed in order to improve the basis and the reliability of the safety standards.

  3. Reliability evaluation of the power supply of an electrical power net for safety-relevant applications

    International Nuclear Information System (INIS)

    Dominguez-Garcia, Alejandro D.; Kassakian, John G.; Schindall, Joel E.

    2006-01-01

    In this paper, we introduce a methodology for the dependability analysis of new automotive safety-relevant systems. With the introduction of safety-relevant electronic systems in cars, it is necessary to carry out a thorough dependability analysis of those systems to fully understand and quantify the failure mechanisms in order to improve the design. Several system level FMEAs are used to identify the different failure modes of the system and, a Markov model is constructed to quantify their probability of occurrence. A new power net architecture with application to new safety-relevant automotive systems, such as Steer-by-Wire or Brake-by-Wire, is used as a case study. For these safety-relevant loads, loss of electric power supply means loss of control of the vehicle. It is, therefore, necessary and critical to develop a highly dependable power net to ensure power to these loads under all circumstances

  4. 1988 failure rate screening data for fusion reliability and risk analysis

    International Nuclear Information System (INIS)

    Cadwallader, L.C.; Piet, S.J.

    1988-01-01

    This document contains failure rate screening data for application to fusion components. The screening values are generally fission or aerospace industry failure rate estimates that can be extrapolated for use by fusion system designers, reliability engineers and risk analysts. Failure rate estimates for tritium-bearing systems, liquid metal-cooled systems, gas-cooled systems, water-cooled systems and containment systems are given. Preliminary system availability estimates and selected initiating event frequency estimates are presented. This first edition document is valuable to design and safety analysis for the Compact Ignition Tokamak and the International Thermonuclear Experimental Reactor. 20 refs., 28 tabs

  5. Final Report to the National Energy Technology Laboratory on FY09-FY13 Cooperative Research with the Consortium for Electric Reliability Technology Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Vittal, Vijay [Arizona State Univ., Mesa, AZ (United States)

    2015-11-04

    The Consortium for Electric Reliability Technology Solutions (CERTS) was formed in 1999 in response to a call from U.S. Congress to restart a federal transmission reliability R&D program to address concerns about the reliability of the U.S. electric power grid. CERTS is a partnership between industry, universities, national laboratories, and government agencies. It researches, develops, and disseminates new methods, tools, and technologies to protect and enhance the reliability of the U.S. electric power system and the efficiency of competitive electricity markets. It is funded by the U.S. Department of Energy’s Office of Electricity Delivery and Energy Reliability (OE). This report provides an overview of PSERC and CERTS, of the overall objectives and scope of the research, a summary of the major research accomplishments, highlights of the work done under the various elements of the NETL cooperative agreement, and brief reports written by the PSERC researchers on their accomplishments, including research results, publications, and software tools.

  6. A roadmap for production of sustainable, consistent and reliable electric power from agricultural biomass- An Indian perspective

    International Nuclear Information System (INIS)

    Singh, Jaswinder

    2016-01-01

    The utilization of agricultural biomass for production of electric power can help to reduce the environmental emissions while achieving energy security and sustainable development. This paper presents a methodology for estimating the power production potential of agricultural biomass in a country. Further, the methodology has been applied to develop a roadmap for producing reliable power in India. The present study reveals that about 650 Mt/year of agricultural biomass is generated in India, while about one-third of this has been found to be surplus for energy applications. The cereal crops have major contribution (64.60%) in production of surplus biomass followed by sugarcane (24.60%) and cotton (10.68%). The energy potential of these resources is of the order of 3.72 EJ, which represents a significant proportion of the primary energy consumption in the country. These biomass resources can produce electric power of 23–35 GW depending upon the efficiency of thermal conversion. The delivery of biomass to the plants and selection of appropriate technology have been found as the major issues that need to be resolved carefully. In the end, the study summarizes various technological options for biomass collection and utilization that can be used for producing clean and consistent power supply. - Highlights: •The production of bioelectricity in India is imperative and inevitable. •About one-third of the agricultural biomass is available for power generation. •The power potential of these resources is of the order of 23–31 GW. •The delivery of biomass to plants and technology selection are the key issues. •India should exploit these resources for producing clean and reliable power.

  7. Competitive electricity markets around the world: approaches to price risk management

    International Nuclear Information System (INIS)

    Masson, G.S.

    1999-01-01

    This chapter focuses on wholesale electricity markets, and traces the histories of the US and UK power industries. Risk management in the new electricity market is examined covering price risk, location basis risk, volume risk, and margin and cross-commodity risk. Specific competitive market systems that have been implemented around the world including mandatory pools, voluntary pools, and bilateral markets are discussed. Panels describing the functions of ancillary services, electricity price volatility, and the problems of capacity payments and the UK pool are presented

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

    International Nuclear Information System (INIS)

    Fragola, J.R.

    1984-01-01

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

  9. Providing reliable equipment to IAEA through a low risk transition plan

    International Nuclear Information System (INIS)

    Green, L.; Weinstock, E.V.; Karlin, E.W.

    1988-01-01

    The development and production of safeguards equipment is a complex process containing many potential pitfalls between the conceptual design and its implementation in the field. The conditions for equipment use are especially demanding. At the same time, the consequences of failure may be serious. Repeated failure may result in the loss of credibility of safeguards. Expensive back up measures such as re-verification of inventories may be required. Inspectors may come to distrust the equipment. Finally, the expense of maintaining the equipment may be excessive. It is therefore essential that the process for bringing equipment for the conceptual stage to actual routine use minimizes the risk of producing equipment that is unsuitable for the job. Fortunately, approaches for accomplishing this have already been developed in both the industrial and commercial sectors. One such approach, the Low Risk Transition Plan (LRTP) is described to show it can be applied to the production of reliable safeguards equipment

  10. The link between personality type and the risk of occupational electrical injury

    Energy Technology Data Exchange (ETDEWEB)

    Howe, Gavan

    2011-09-15

    Personality type has a very important impact on many occupations and on day-to-day life. A 2006 survey found that over 80% of all electricians have an extrovert profile which is related to risk-bearing (agreeableness) and risk-taking. Non-critical, occupational electrical and powerline accidents doubled from 1998 to 2006. Other trade workers (not electricians) suffer 80% of all occupational deaths due to electrical contact. And young, single, male, extroverted, electrical apprentices are the most vulnerable workers when around electricity. Electricians are vulnerable to electrical accidents. They lack in-depth, day-to-day, supervised training around electricity. By researching the link between personality type and the risk of occupational electrical injury, we can determine which types of workers' profile we need on the job site. Training, education, communications and rehabilitation plans can be modified to safeguard workers' safety.

  11. The Comprehensive Evaluation Method of Supervision Risk in Electricity Transaction Based on Unascertained Rational Number

    Science.gov (United States)

    Haining, Wang; Lei, Wang; Qian, Zhang; Zongqiang, Zheng; Hongyu, Zhou; Chuncheng, Gao

    2018-03-01

    For the uncertain problems in the comprehensive evaluation of supervision risk in electricity transaction, this paper uses the unidentified rational numbers to evaluation the supervision risk, to obtain the possible result and corresponding credibility of evaluation and realize the quantification of risk indexes. The model can draw the risk degree of various indexes, which makes it easier for the electricity transaction supervisors to identify the transaction risk and determine the risk level, assisting the decision-making and realizing the effective supervision of the risk. The results of the case analysis verify the effectiveness of the model.

  12. Mortality and risk of cardiac complications among immediate survivors of accidental electric shock

    DEFF Research Database (Denmark)

    Hansen, Steen Møller; Riahi, Sam; Hjortshøj, Søren

    2017-01-01

    OBJECTIVE: Exposure to electric shock has been associated with an increased risk of developing delayed cardiac arrhythmias and cardiac diseases. We examined whether electric shock patients have an increased risk of developing cardiac disease, cardiac arrhythmias or death compared with the general...... suggest that nearly all patients can be discharged safely from the emergency room after electric shock without further observation.......OBJECTIVE: Exposure to electric shock has been associated with an increased risk of developing delayed cardiac arrhythmias and cardiac diseases. We examined whether electric shock patients have an increased risk of developing cardiac disease, cardiac arrhythmias or death compared with the general...... Danish population. DESIGN: Matched cohort study. SETTING: A nationwide study in Denmark from 1994 to 2011. PARTICIPANTS: We identified 11 462 Danish patients who visited an emergency ward or were admitted to a hospital due to electric shock from 1994 to 2011. Each patient was matched for age and sex...

  13. 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

  14. Study of reliability for the electricity cogeneration and seawater desalination in the Northwest of Mexico

    International Nuclear Information System (INIS)

    Hernandez U, G. O.; Ortega C, R. F.

    2008-01-01

    were costs very competitive of 0.038-0.044 $/ kWh for the production of electric energy and of 0.60 at 0.77 $/ m 3 for the produced water, with a lost of power in the generation of among 28 to 43 MW e . (Author)

  15. 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.

  16. Human reliability and risk management in the transportation of spent nuclear fuel

    International Nuclear Information System (INIS)

    Tuler, S.; Kasperson, R.E.; Ratick, S.

    1989-01-01

    This paper summarizes work on human factor contributions to risks from spent nuclear fuel transportation. Human participation may have significant effects on the levels and types of risks by enabling or initiating incidents and exacerbating adverse consequences. Human errors are defined to be the result of mismatches between perceived system state and actual system state. In complex transportation systems such mismatches may be distributed in time (e.g., during different stages of design, implementation, operation, maintenance) and location (e.g., human error, its identification, and its recovery may be geographically and institutionally separate). Risk management programs may decrease the probability of undesirable events or attenuate the consequences of mismatches. This paper presents a methodology to identify the scope and types of human-task mismatches and to identify potential management options for their prevention, mitigation, or recovery. A review of transportation accident databases, in conjunction with human error models, is used to develop a taxonomy of human errors during design for the pre-identification of potential mismatches or after incidents have occurred to evaluate their causes. Risk management options to improve human reliability are identified by a matrix that relates the multiple stages of a spent nuclear fuel transportation system to management options (e.g., training, data analysis, regulation). The paper concludes with examples to illustrate how the methodology may be applied. (author)

  17. A model for reliability avaliation of the electrical supply source of the 1A3 and 1A4 control rods assemblies of Angra I reactor

    International Nuclear Information System (INIS)

    Yang, T.

    1978-01-01

    The reliability of the electrical power supply to the 4.16KV buses for the safety system operation of a nuclear power plant was studied. Particularly, Angra Unit I system was focused. Initially, reliability of each electrical supply source was estimated. Using a probabilistic approach based on the Markov processes, the system reliability was evaluated in terms of frequency and duration of loss of power supply and of the system failure probability evolution when one or more sources remained unavailable. Based on these results, certain reactor operating rules were proposed concerning later shutdown of the plant without compromising the nuclear reactor safety. A sensitivity analysis was also performed to show the different reliability parameter influences on final results. This analysis showed that the diesel system performs an important role in the power supply for a nuclear power plant [pt

  18. Three essays on pricing and risk management in electricity markets

    Science.gov (United States)

    Kotsan, Serhiy

    2005-07-01

    A set of three papers forms this dissertation. In the first paper I analyze an electricity market that does not clear. The system operator satisfies fixed demand at a fixed price, and attempts to minimize "cost" as indicated by independent generators' supply bids. No equilibrium exists in this situation, and the operator lacks information sufficient to minimize actual cost. As a remedy, we propose a simple efficient tax mechanism. With the tax, Nash equilibrium bids still diverge from marginal cost but nonetheless provide sufficient information to minimize actual cost, regardless of the tax rate or number of generators. The second paper examines a price mechanism with one price assigned for each level of bundled real and reactive power. Equilibrium allocation under this pricing approach raises system efficiency via better allocation of the reactive power reserves, neglected in the traditional pricing approach. Pricing reactive power should be considered in the bundle with real power since its cost is highly dependent on real power output. The efficiency of pricing approach is shown in the general case, and tested on the 30-bus IEEE network with piecewise linear cost functions of the generators. Finally the third paper addresses the problem of optimal investment in generation based on mean-variance portfolio analysis. It is assumed the investor can freely create a portfolio of shares in generation located on buses of the electrical network. Investors are risk averse, and seek to minimize the variance of the weighted average Locational Marginal Price (LMP) in their portfolio, and to maximize its expected value. I conduct simulations using a standard IEEE 68-bus network that resembles the New York - New England system and calculate LMPs in accordance with the PJM methodology for a fully optimal AC power flow solution. Results indicate that the network topology is a crucial determinant of the investment decision as line congestion makes it difficult to deliver power to

  19. A new active portfolio risk management for an electricity retailer based on a drawdown risk preference

    International Nuclear Information System (INIS)

    Charwand, Mansour; Gitizadeh, Mohsen; Siano, Pierluigi

    2017-01-01

    This paper addresses the deciding under uncertainty of an electricity retailer in order to maximise its total expected rate of return. The developed methodology is based on the modelling of the stochastic evolution of zonal prices that seeks to manage a portfolio of different contracts. Retailer's load and the price at each zone are forecasted using the seasonal autoregressive integrated moving average (SARIMA) model and a clustering technique is used for scenario reduction. Supply sources include the pool, self-production facilities, forward and bilateral contracts. The risk of cost fluctuation due to uncertainties is explicitly modelled using the multi-scenario drawdown methodology. This risk function quantifies in aggregated format the frequency and magnitude of the portfolio drawdowns over planning horizon. In-sample and out-of-sample runs are performed for a portfolio allocation problem. Carried out experimental results on the basis of realistic data, show that imposing risk constraints improve the “real” performance of a portfolio management in out-of-sample runs. - Highlights: • A new drawdown-based method is introduced to retailer deciding under uncertainty. • This tool is used to assess the risk levels regarding retailer midterm strategies. • The methodology is based on the modeling of the stochastic evolution of zonal prices. • The risk function quantifies the frequency and magnitude of the portfolio drawdowns. • In-sample and out-of-sample runs are performed for a portfolio allocation problem.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-07-01

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

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

    International Nuclear Information System (INIS)

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

    2016-01-01

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

  2. Electric power supply and demand 1979 to 1988 for the contiguous United States as projected by the Regional Electric Reliability Councils in their April 1, 1979 long-range coordinated planning reports to the Department of Energy

    Energy Technology Data Exchange (ETDEWEB)

    Savage, N.; Graban, W.

    1979-12-01

    Information concerning bulk electric power supply and demand is summarized and reviewed. Electric-utility power-supply systems are composed of power sources, transmission and distribution facilities, and users of electricity. In the United States there are three such systems of large geographic extent that together cover the entire country. Subjects covered are: energy forecasts, peak demand forecasts, generating-capacity forecasts, purchases and sales of capacity, and transmission. Extensive data are compiled in 17 tables. Information in two appendices includes a general description of the Regional Electric Reliability Councils and US generating capacity as of June 30, 1979. 3 figures, 17 tables.

  3. Using electricity options to hedge against financial risks of power producers

    DEFF Research Database (Denmark)

    Pineda Morente, Salvador; Conejo, Antonio J.

    2013-01-01

    or unexpected unit failures faced by power producers. A multi-stage stochastic model is described in this tutorial paper to determine the optimal forward and option contracting decisions for a risk-averse power producer. The key features of electricity options to reduce both price and availability risks......As a consequence of competition in electricity markets, a wide variety of financial derivatives have emerged to allow market agents to hedge against risks. Electricity options and forward contracts constitute adequate instruments to manage the financial risks pertaining to price volatility...

  4. Is qPCR a Reliable Indicator of Cyanotoxin Risk in Freshwater?

    Science.gov (United States)

    Pacheco, Ana Beatriz F.; Guedes, Iame A.; Azevedo, Sandra M.F.O.

    2016-01-01

    The wide distribution of cyanobacteria in aquatic environments leads to the risk of water contamination by cyanotoxins, which generate environmental and public health issues. Measurements of cell densities or pigment contents allow both the early detection of cellular growth and bloom monitoring, but these methods are not sufficiently accurate to predict actual cyanobacterial risk. To quantify cyanotoxins, analytical methods are considered the gold standards, but they are laborious, expensive, time-consuming and available in a limited number of laboratories. In cyanobacterial species with toxic potential, cyanotoxin production is restricted to some strains, and blooms can contain varying proportions of both toxic and non-toxic cells, which are morphologically indistinguishable. The sequencing of cyanobacterial genomes led to the description of gene clusters responsible for cyanotoxin production, which paved the way for the use of these genes as targets for PCR and then quantitative PCR (qPCR). Thus, the quantification of cyanotoxin genes appeared as a new method for estimating the potential toxicity of blooms. This raises a question concerning whether qPCR-based methods would be a reliable indicator of toxin concentration in the environment. Here, we review studies that report the parallel detection of microcystin genes and microcystin concentrations in natural populations and also a smaller number of studies dedicated to cylindrospermopsin and saxitoxin. We discuss the possible issues associated with the contradictory findings reported to date, present methodological limitations and consider the use of qPCR as an indicator of cyanotoxin risk. PMID:27338471

  5. Is qPCR a Reliable Indicator of Cyanotoxin Risk in Freshwater?

    Directory of Open Access Journals (Sweden)

    Ana Beatriz F. Pacheco

    2016-06-01

    Full Text Available The wide distribution of cyanobacteria in aquatic environments leads to the risk of water contamination by cyanotoxins, which generate environmental and public health issues. Measurements of cell densities or pigment contents allow both the early detection of cellular growth and bloom monitoring, but these methods are not sufficiently accurate to predict actual cyanobacterial risk. To quantify cyanotoxins, analytical methods are considered the gold standards, but they are laborious, expensive, time-consuming and available in a limited number of laboratories. In cyanobacterial species with toxic potential, cyanotoxin production is restricted to some strains, and blooms can contain varying proportions of both toxic and non-toxic cells, which are morphologically indistinguishable. The sequencing of cyanobacterial genomes led to the description of gene clusters responsible for cyanotoxin production, which paved the way for the use of these genes as targets for PCR and then quantitative PCR (qPCR. Thus, the quantification of cyanotoxin genes appeared as a new method for estimating the potential toxicity of blooms. This raises a question concerning whether qPCR-based methods would be a reliable indicator of toxin concentration in the environment. Here, we review studies that report the parallel detection of microcystin genes and microcystin concentrations in natural populations and also a smaller number of studies dedicated to cylindrospermopsin and saxitoxin. We discuss the possible issues associated with the contradictory findings reported to date, present methodological limitations and consider the use of qPCR as an indicator of cyanotoxin risk.

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

    International Nuclear Information System (INIS)

    Samanta, P.K.

    1981-01-01

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

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

    International Nuclear Information System (INIS)

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

    1987-01-01

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

  8. Interpretations of alternative uncertainty representations in a reliability and risk analysis context

    International Nuclear Information System (INIS)

    Aven, T.

    2011-01-01

    Probability is the predominant tool used to measure uncertainties in reliability and risk analyses. However, other representations also exist, including imprecise (interval) probability, fuzzy probability and representations based on the theories of evidence (belief functions) and possibility. Many researchers in the field are strong proponents of these alternative methods, but some are also sceptical. In this paper, we address one basic requirement set for quantitative measures of uncertainty: the interpretation needed to explain what an uncertainty number expresses. We question to what extent the various measures meet this requirement. Comparisons are made with probabilistic analysis, where uncertainty is represented by subjective probabilities, using either a betting interpretation or a reference to an uncertainty standard interpretation. By distinguishing between chances (expressing variation) and subjective probabilities, new insights are gained into the link between the alternative uncertainty representations and probability.

  9. Commercial Off-The-Shelf (COTS) Parts Risk and Reliability User and Application Guide

    Science.gov (United States)

    White, Mark

    2017-01-01

    All COTS parts are not created equal. Because they are not created equal, the notion that one can force the commercial industry to follow a set of military specifications and standards, along with the certifications, audits and qualification commitments that go with them, is unrealistic for the sale of a few parts. The part technologies that are Defense Logistics Agency (DLA) certified or Military Specification (MS) qualified, are several generations behind the state-of-the-art high-performance parts that are required for the compact, higher performing systems for the next generation of spacecraft and instruments. The majority of the part suppliers are focused on the portion of the market that is producing high-tech commercial products and systems. To that end, in order to compete in the high performance and leading edge advanced technological systems, an alternative approach to risk assessment and reliability prediction must be considered.

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

    International Nuclear Information System (INIS)

    Vierow, Karen; Aldemir, Tunc

    2009-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Vierow, Karen; Aldemir, Tunc

    2009-09-10

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

  12. Creating New Incentives for Risk Identification and Insurance Process for the Electric Utility Industry (initial award through Award Modification 2); Energy & Risk Transfer Assessment (Award Modifications 3 - 6)

    Energy Technology Data Exchange (ETDEWEB)

    Michael Ebert

    2008-02-28

    This is the final report for the DOE-NETL grant entitled 'Creating New Incentives for Risk Identification & Insurance Processes for the Electric Utility Industry' and later, 'Energy & Risk Transfer Assessment'. It reflects work done on projects from 15 August 2004 to 29 February 2008. Projects were on a variety of topics, including commercial insurance for electrical utilities, the Electrical Reliability Organization, cost recovery by Gulf State electrical utilities after major hurricanes, and review of state energy emergency plans. This Final Technical Report documents and summarizes all work performed during the award period, which in this case is from 15 August 2004 (date of notification of original award) through 29 February 2008. This report presents this information in a comprehensive, integrated fashion that clearly shows a logical and synergistic research trajectory, and is augmented with findings and conclusions drawn from the research as a whole. Four major research projects were undertaken and completed during the 42 month period of activities conducted and funded by the award; these are: (1) Creating New Incentives for Risk Identification and Insurance Process for the Electric Utility Industry (also referred to as the 'commercial insurance' research). Three major deliverables were produced: a pre-conference white paper, a two-day facilitated stakeholders workshop conducted at George Mason University, and a post-workshop report with findings and recommendations. All deliverables from this work are published on the CIP website at http://cipp.gmu.edu/projects/DoE-NETL-2005.php. (2) The New Electric Reliability Organization (ERO): an examination of critical issues associated with governance, standards development and implementation, and jurisdiction (also referred to as the 'ERO study'). Four major deliverables were produced: a series of preliminary memoranda for the staff of the Office of Electricity Delivery and

  13. Validation and inter-rater reliability of a three item falls risk screening tool

    Directory of Open Access Journals (Sweden)

    Catherine Maree Said

    2017-11-01

    Full Text Available Abstract Background Falls screening tools are routinely used in hospital settings and the psychometric properties of tools should be examined in the setting in which they are used. The aim of this study was to explore the concurrent and predictive validity of the Austin Health Falls Risk Screening Tool (AHFRST, compared with The Northern Hospital Modified St Thomas’s Risk Assessment Tool (TNH-STRATIFY, and the inter-rater reliability of the AHFRST. Methods A research physiotherapist used the AHFRST and TNH-STRATIFY to classify 130 participants admitted to Austin Health (five acute wards, n = 115 two subacute wards n = 15; median length of stay 6 days IQR 3–12 as ‘High’ or ‘Low’ falls risk. The AHFRST was also completed by nursing staff on patient admission. Falls data was collected from the hospital incident reporting system. Results Six falls occurred during the study period (fall rate of 4.6 falls per 1000 bed days. There was substantial agreement between the AHFRST and the TNH-STRATIFY (Kappa = 0.68, 95% CI 0.52–0.78. Both tools had poor predictive validity, with low specificity (AHFRST 46.0%, 95% CI 37.0–55.1; TNH-STRATIFY 34.7%, 95% CI 26.4–43.7 and positive predictive values (AHFRST 5.6%, 95% CI 1.6–13.8; TNH-STRATIFY 6.9%, 95% CI 2.6–14.4. The AHFRST showed moderate inter-rater reliability (Kappa = 0.54, 95% CI = 0.36–0.67, p < 0.001 although 18 patients did not have the AHFRST completed by nursing staff. Conclusions There was an acceptable level of agreement between the 3 item AHFRST classification of falls risk and the longer, 9 item TNH-STRATIFY classification. However, both tools demonstrated limited predictive validity in the Austin Health population. The results highlight the importance of evaluating the validity of falls screening tools, and the clinical utility of these tools should be reconsidered.

  14. Reliability, Resilience, and Vulnerability criteria for the evaluation of Human Health Risks

    Science.gov (United States)

    Rodak, C. M.; Silliman, S. E.; Bolster, D.

    2011-12-01

    Understanding the impact of water quality on the health of a general population is challenging due high degrees of uncertainty and variability in hydrological, toxicological and human aspects of the system. Assessment of the impact of changes in water quality of a public water supply is critical to management of that water supply. We propose the use of three different system evaluation criteria: Reliability, Resilience and Vulnerability (RRV) as a tool for assessing the impact of uncertainty in the arrival of contaminant mass through time with respect to human health risks on a variable population. These criteria were first introduced to the water resources community by Hashimoto et al (1982). Most simply one can understand these criteria as the following: Reliability is the likelihood of the system being in a state of success; Resilience is the probability that the system will return to a state of success at t+1 if it is in failure at time step t, and Vulnerability is the severity of failure, which here is defined as the maximum health risk. These concepts are applied to a theoretical example where the water quality at a water supply well varies over time: health impact is considered based on sliding, 30-year windows of exposure to water derived from the well. We apply the methodology, in terms of uncertainty in water quality deviations, to eight simulated breakthrough curves of a contaminant at the well: each curve represents equal mass of contaminant arriving at the well over a 70-year lifetime of the well, but different mass distributions over time. These curves are used to investigate the impact of uncertainty in the distribution through time of the contaminant mass at the well, as well as the initial arrival of the contaminant over the 70-year lifetime of the well. In addition to extending the health risk through time with uncertainty in mass distribution, we incorporate variability in the human population to examine the evolution of the three criteria within

  15. Investigations of safety risks in converted electric vehicles

    NARCIS (Netherlands)

    Bolech, M.; Foster, D.L.; Lange, R. de; Rodarius, C.

    2010-01-01

    Within the departments Environmentally Sustainable Transport and Automotive of TNO (Netherlands organisation for applied scientific research) several projects investigating safety aspects of electric vehicles have been conducted, including one in cooperation with KEMA and RDW of the Netherlands.

  16. Job Exposure Matrix for Electric Shock Risks with Their Uncertainties

    Science.gov (United States)

    Vergara, Ximena P.; Fischer, Heidi J.; Yost, Michael; Silva, Michael; Lombardi, David A.; Kheifets, Leeka

    2015-01-01

    We present an update to an electric shock job exposure matrix (JEM) that assigned ordinal electric shocks exposure for 501 occupational titles based on electric shocks and electrocutions from two available data sources and expert judgment. Using formal expert elicitation and starting with data on electric injury, we arrive at a consensus-based JEM. In our new JEM, we quantify exposures by adding three new dimensions: (1) the elicited median proportion; (2) the elicited 25th percentile; and (3) and the elicited 75th percentile of those experiencing occupational electric shocks in a working lifetime. We construct the relative interquartile range (rIQR) based on uncertainty interval and the median. Finally, we describe overall results, highlight examples demonstrating the impact of cut point selection on exposure assignment, and evaluate potential impacts of such selection on epidemiologic studies of the electric work environment. In conclusion, novel methods allowed for consistent exposure estimates that move from qualitative to quantitative measures in this population-based JEM. Overlapping ranges of median exposure in various categories reflect our limited knowledge about this exposure. PMID:25856552

  17. Job Exposure Matrix for Electric Shock Risks with Their Uncertainties

    Directory of Open Access Journals (Sweden)

    Ximena P. Vergara

    2015-04-01

    Full Text Available We present an update to an electric shock job exposure matrix (JEM that assigned ordinal electric shocks exposure for 501 occupational titles based on electric shocks and electrocutions from two available data sources and expert judgment. Using formal expert elicitation and starting with data on electric injury, we arrive at a consensus-based JEM. In our new JEM, we quantify exposures by adding three new dimensions: (1 the elicited median proportion; (2 the elicited 25th percentile; and (3 and the elicited 75th percentile of those experiencing occupational electric shocks in a working lifetime. We construct the relative interquartile range (rIQR based on uncertainty interval and the median. Finally, we describe overall results, highlight examples demonstrating the impact of cut point selection on exposure assignment, and evaluate potential impacts of such selection on epidemiologic studies of the electric work environment. In conclusion, novel methods allowed for consistent exposure estimates that move from qualitative to quantitative measures in this population-based JEM. Overlapping ranges of median exposure in various categories reflect our limited knowledge about this exposure.

  18. Weak Satiety Responsiveness Is a Reliable Trait Associated with Hedonic Risk Factors for Overeating among Women.

    Science.gov (United States)

    Dalton, Michelle; Hollingworth, Sophie; Blundell, John; Finlayson, Graham

    2015-09-04

    Some individuals exhibit a weak satiety response to food and may be susceptible to overconsumption. The current study identified women showing consistently low or high satiety responses to standardised servings of food across four separate days and compared them on behavioural, psychological and physiological risk factors for overeating and future weight gain. In a crossover design, 30 female participants (age: 28.0 ± 10.6; body mass index (BMI): 23.1 ± 3.0) recorded sensations of hunger in the post-prandial period following four graded energy level breakfasts. Satiety quotients were calculated to compare individuals on satiety responsiveness across conditions. Body composition, resting metabolic rate (RMR), energy intake, food reward and craving, and eating behaviour traits were assessed under controlled laboratory conditions. A distinct low satiety phenotype (LSP) was identified with good consistency across separate study days. These individuals had a higher RMR, greater levels of disinhibition and reported feeling lower control over food cravings. Further, they consumed more energy and exhibited greater wanting for high-fat food. The inverse pattern of characteristics was observed in those exhibiting a consistently high satiety phenotype (HSP). Weak satiety responsiveness is a reliable trait identifiable using the satiety quotient. The LSP was characterised by distinct behavioural and psychological characteristics indicating a risk for overeating, compared to HSP.

  19. Weak Satiety Responsiveness Is a Reliable Trait Associated with Hedonic Risk Factors for Overeating among Women

    Directory of Open Access Journals (Sweden)

    Michelle Dalton

    2015-09-01

    Full Text Available Some individuals exhibit a weak satiety response to food and may be susceptible to overconsumption. The current study identified women showing consistently low or high satiety responses to standardised servings of food across four separate days and compared them on behavioural, psychological and physiological risk factors for overeating and future weight gain. In a crossover design, 30 female participants (age: 28.0 ± 10.6; body mass index (BMI: 23.1 ± 3.0 recorded sensations of hunger in the post-prandial period following four graded energy level breakfasts. Satiety quotients were calculated to compare individuals on satiety responsiveness across conditions. Body composition, resting metabolic rate (RMR, energy intake, food reward and craving, and eating behaviour traits were assessed under controlled laboratory conditions. A distinct low satiety phenotype (LSP was identified with good consistency across separate study days. These individuals had a higher RMR, greater levels of disinhibition and reported feeling lower control over food cravings. Further, they consumed more energy and exhibited greater wanting for high-fat food. The inverse pattern of characteristics was observed in those exhibiting a consistently high satiety phenotype (HSP. Weak satiety responsiveness is a reliable trait identifiable using the satiety quotient. The LSP was characterised by distinct behavioural and psychological characteristics indicating a risk for overeating, compared to HSP.

  20. External hazards in reliability and risk assessment of nuclear power plants

    International Nuclear Information System (INIS)

    Stevenson, J.D.

    1977-01-01

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

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

    International Nuclear Information System (INIS)

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

    1985-01-01

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

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

    International Nuclear Information System (INIS)

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

    1984-10-01

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

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

    International Nuclear Information System (INIS)

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

    1991-03-01

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

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

    International Nuclear Information System (INIS)

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

    1990-06-01

    The Integrated Reliability and Risk Analysis System (IRRAS) is a state-of-the-art, microcomputer-based probabilistic risk assessment (PRA) model development and analysis tool to address key nuclear plant safety issues. IRRAS is an integrated software tool that gives the user the ability to create and analyze fault trees and accident sequences using a microcomputer. This program provides functions that range from graphical fault tree construction to cut set generation and quantification. Also provided in the system is an integrated full-screen editor for use when interfacing with remote mainframe computer systems. Version 1.0 of the IRRAS program was released in February of 1987. Since that time, many user comments and enhancements have been incorporated into the program providing a much more powerful and user-friendly system. This version has been designated IRRAS 2.0 and is the subject of this user's guide. Version 2.0 of IRRAS provides all of the same capabilities as Version 1.0 and adds a relational data base facility for managing the data, improved functionality, and improved algorithm performance. 9 refs., 292 figs., 4 tabs

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

    International Nuclear Information System (INIS)

    Swain, A.D.

    1986-01-01

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

  6. Evaluation of the reliability of electric power transmission systems; Evaluacion de confiabilidad de sistemas de transmision de energia electrica

    Energy Technology Data Exchange (ETDEWEB)

    Vega Ortiz, Miguel

    1989-07-01

    In this thesis it is attacked the problem of Reliability Evaluation of the Electrical Power Transmission Systems for aims of its integral planning. Once described the problem the indexes that measure the electric power systems reliability are presented. Later the methods to evaluate the transmission nets, such as the Contingencies Enumeration, the Monte Carlo, the one of Markov and the methods for complex systems such as the Minimum Interruptions, are described. This last one is widely developed for the advantages that its application presents in the planning of large and complex networks. The method of minimum interruptions consists of two big steps: To determine the minimum interruptions for the load points and to calculate the reliability indexes in base of the minimum interruptions. The conventional algorithms for the determination of minimum interruptions consider a problem for each load point in an independent form going through a determination of minimum tracks. In this type of algorithms the CPU time and the space in memory required grow exponentially for the case of large transmission systems, which represents a strong restriction for its application. In order to solve this problem a methodology was established in which the system is modeled by means of a grapho and the minimum interruptions are determined with an algorithm based on the construction of cycles in the dual grapho. With these interruptions the connectivity and the capacity of the network is evaluated, obtaining the reliability indexes for each bus and the system. These indexes are calculated with the equivalent representation for complex systems of series parallel connections defined by the minimum interruptions. One of the fundamental objectives in this study is to integrate the reliability to the planning process, with the concept of the expected value of the non-supplied energy and its penalty cost. In order to demonstrate the capacity, effectiveness and rapidity of the new implemented

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

    International Nuclear Information System (INIS)

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

    1994-07-01

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

  8. Quantifying price risk of electricity retailer based on CAPM and RAROC methodology

    International Nuclear Information System (INIS)

    Karandikar, R.G.; Khaparde, S.A.; Kulkarni, S.V.

    2007-01-01

    In restructured electricity markets, electricity retailers set up contracts with generation companies (GENCOs) and with end users to meet their load requirements at agreed upon tariff. The retailers invest consumer payments as capital in the volatile competitive market. In this paper, a model for quantifying price risk of electricity retailer is proposed. An IEEE 30 Bus test system is used to demonstrate the model. The Capital Asset Pricing Model (CAPM) is demonstrated to determine the retail electricity price for the end users. The factor Risk Adjusted Recovery on Capital (RAROC) is used to quantify the price risk involved. The methodology proposed in this paper can be used by retailer while submitting proposal for electricity tariff to the regulatory authority. (author)

  9. Quantifying price risk of electricity retailer based on CAPM and RAROC methodology

    Energy Technology Data Exchange (ETDEWEB)

    Karandikar, R.G.; Khaparde, S.A.; Kulkarni, S.V. [Electrical Engineering Department, Indian Institute of Technology Bombay, Mumbai 400 076 (India)

    2007-12-15

    In restructured electricity markets, electricity retailers set up contracts with generation companies (GENCOs) and with end users to meet their load requirements at agreed upon tariff. The retailers invest consumer payments as capital in the volatile competitive market. In this paper, a model for quantifying price risk of electricity retailer is proposed. An IEEE 30 Bus test system is used to demonstrate the model. The Capital Asset Pricing Model (CAPM) is demonstrated to determine the retail electricity price for the end users. The factor Risk Adjusted Recovery on Capital (RAROC) is used to quantify the price risk involved. The methodology proposed in this paper can be used by retailer while submitting proposal for electricity tariff to the regulatory authority. (author)

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

    Science.gov (United States)

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

    2012-10-15

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

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

    Science.gov (United States)

    Sari, Çiğdem; Altay, Naime

    2017-03-01

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

  12. A risk assessment model based on fuzzy logic for electricity distribution system asset management

    Directory of Open Access Journals (Sweden)

    Alireza Yazdani

    2014-06-01

    Full Text Available Electricity distribution systems are considered as the most critical sectors in countries because of the essentiality of power supplement security, socioeconomic security, and way of life. According to the central role of electricity distribution systems, risk analysis helps decision maker determine the most serious risk items to allocate the optimal amount of resources and time. Probability-impact (PI matrix is one of the most popular methods for assessment of the risks involved in the system. However, the traditional PI matrix is criticized for its inability to take into account the inherent uncertainty imposed by real-world systems. On the other hand, fuzzy sets are capable of handling the uncertainty. Thus, in this paper, fuzzy risk assessment model is developed in order to assess risk and management for electricity distribution system asset protection. Finally, a comparison analysis is conducted to show the effectiveness and the capability of the new risk assessment model.

  13. BECCS Market Launch Strategy Aiming to Help Ensure Reliable Grid Power at High Penetrations of IRE (Intermittent Renewable Electricity)

    Science.gov (United States)

    WIlliams, R. H.

    2017-12-01

    Despite its recognized importance for carbon (C)-mitigation, progress in advancing biomass energy with CO2 capture and sequestration (BECCS) has been slow. A BECCS market launch strategy based on technologies ready for commercial-scale demonstration is discussed—based on co-gasification of coal and biomass to make H2 with CCS. H2 so produced would be a key element of a H2 balancing capacity (H2-BC) strategy for ensuring reliable grid power at high IRE penetrations. High grid penetrations of IRE must be complemented by fast-ramping balancing (backup and/or storage) capacity (BC) to ensure reliable grid power. BC provided now by natural gas-fired gas turbine combined cycle and combustion turbine units would eventually have to be decarbonized to realize C-mitigation goals, via CCS or other means. Capital-intensive CCS energy systems require baseload operation to realize favourable economics, but at high IRE penetrations, BC plants must be operated at low capacity factors. A H2-BC strategy is a promising way to address this challenge. The elements of a H2-BC system are: (a) H2 production from carbonaceous feedstocks in baseload plants with CCS; (b) H2 consumption in fast-ramping BC units that operate at low capacity factors; (c) Buffer underground H2 storage to enable decoupling baseload H2 production from highly variable H2 consumption by BC units. The concept is likely to "work" because underground H2 storage is expected to be inexpensive. A H2 production analysis is presented for a negative GHG-emitting H2-BC system based on cogasification of corn stover and coal, with captured CO2 used for enhanced oil recovery. The technical readiness of each system component is discussed, and preliminary insights are offered as to the conditions under which the corresponding H2-BC system might compete with natural gas in providing backup for IRE on US electric grids. Public policy to help advance this strategy might be forthcoming, because 2 US Senate bills with broad

  14. Guide to the collection and presentation of electrical, electronic, and sensing component reliability data for nuclear-power generating stations

    International Nuclear Information System (INIS)

    Anon.

    1979-01-01

    This Guide is intended to establish a method of collecting and presenting reliability data for quantitative systematic reliability analysis in nuclear power generating stations, as outlined in IEEE Std 351-1975. Appendix D, which is not a part of IEEE Std 500-1977 but which comprises the bulk of this publication, presents tables of reliability data for nuclear power generating stations, intended for use of nuclear systems reliability analysts or design engineers

  15. 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...

  16. The explicit treatment of model uncertainties in the presence of aleatory and epistemic parameter uncertainties in risk and reliability analysis

    International Nuclear Information System (INIS)

    Ahn, Kwang Il; Yang, Joon Eon

    2003-01-01

    In the risk and reliability analysis of complex technological systems, the primary concern of formal uncertainty analysis is to understand why uncertainties arise, and to evaluate how they impact the results of the analysis. In recent times, many of the uncertainty analyses have focused on parameters of the risk and reliability analysis models, whose values are uncertain in an aleatory or an epistemic way. As the field of parametric uncertainty analysis matures, however, more attention is being paid to the explicit treatment of uncertainties that are addressed in the predictive model itself as well as the accuracy of the predictive model. The essential steps for evaluating impacts of these model uncertainties in the presence of parameter uncertainties are to determine rigorously various sources of uncertainties to be addressed in an underlying model itself and in turn model parameters, based on our state-of-knowledge and relevant evidence. Answering clearly the question of how to characterize and treat explicitly the forgoing different sources of uncertainty is particularly important for practical aspects such as risk and reliability optimization of systems as well as more transparent risk information and decision-making under various uncertainties. The main purpose of this paper is to provide practical guidance for quantitatively treating various model uncertainties that would often be encountered in the risk and reliability modeling process of complex technological systems

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

    Science.gov (United States)

    Shafiee-Jood, M.; Cai, X.

    2017-12-01

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

  18. Risk-return incentives in liberalised electricity markets

    NARCIS (Netherlands)

    Lynch, Muireann Á; Shortt, Aonghus; Tol, Richard S.J.; O'Malley, Mark J.

    2013-01-01

    We employ Monte Carlo analysis to determine the distribution of returns for various electricity generation technologies. Costs and revenues for each technology are calculated by means of a unit commitment and economic dispatch algorithm at hourly resolution. This represents a considerable

  19. Accuracy and reliability of noninvasive stroke volume monitoring via ECG-gated 3D electrical impedance tomography in healthy volunteers

    Science.gov (United States)

    Proença, Martin; Adler, Andy; Riedel, Thomas; Thiran, Jean-Philippe; Solà, Josep

    2018-01-01

    Cardiac output (CO) and stroke volume (SV) are parameters of key clinical interest. Many techniques exist to measure CO and SV, but are either invasive or insufficiently accurate in clinical settings. Electrical impedance tomography (EIT) has been suggested as a noninvasive measure of SV, but inconsistent results have been reported. Our goal is to determine the accuracy and reliability of EIT-based SV measurements, and whether advanced image reconstruction approaches can help to improve the estimates. Data were collected on ten healthy volunteers undergoing postural changes and exercise. To overcome the sensitivity to heart displacement and thorax morphology reported in previous work, we used a 3D EIT configuration with 2 planes of 16 electrodes and subject-specific reconstruction models. Various EIT-derived SV estimates were compared to reference measurements derived from the oxygen uptake. Results revealed a dramatic impact of posture on the EIT images. Therefore, the analysis was restricted to measurements in supine position under controlled conditions (low noise and stable heart and lung regions). In these measurements, amplitudes of impedance changes in the heart and lung regions could successfully be derived from EIT using ECG gating. However, despite a subject-specific calibration the heart-related estimates showed an error of 0.0 ± 15.2 mL for absolute SV estimation. For trending of relative SV changes, a concordance rate of 80.9% and an angular error of −1.0 ± 23.0° were obtained. These performances are insufficient for most clinical uses. Similar conclusions were derived from lung-related estimates. Our findings indicate that the key difficulty in EIT-based SV monitoring is that purely amplitude-based features are strongly influenced by other factors (such as posture, electrode contact impedance and lung or heart conductivity). All the data of the present study are made publicly available for further investigations. PMID:29373611

  20. Comparing the risk profiles of renewable and natural gas electricity contracts: A summary of the California Department of Water Resources contracts

    Energy Technology Data Exchange (ETDEWEB)

    Bachrach, Devra; Wiser, Ryan; Bolinger, Mark; Golove, William

    2003-03-12

    Electricity markets in the United States have witnessed unprecedented instability over the last few years, with substantial volatility in wholesale market prices, significant financial distress among major industry organizations, and unprecedented legal, regulatory and legislative activity. These events demonstrate the considerable risks that exist in the electricity industry. Recent industry instability also illustrates the need for thoughtful resource planning to balance the cost, reliability, and risk of the electricity supplied to end-use customers. In balancing different supply options, utilities, regulators, and other resource planners must consider the unique risk profiles of each generating source. This paper evaluates the relative risk profiles of renewable and natural gas generating plants. The risks that exist in the electricity industry depend in part on the technologies that are used to generate electricity. Natural gas has become the fuel of choice for new power plant additions in the United States. To some, this emphasis on a single fuel source signals the potential for increased risk. Renewable generation sources, on the other hand, are frequently cited as a potent source of socially beneficial risk reduction relative to natural gas-fired generation. Renewable generation is not risk free, however, and also imposes certain costs on the electricity sector. This paper specifically compares the allocation and mitigation of risks in long-term natural gas-fired electricity contracts with the allocation and mitigation of these same risks in long-term renewable energy contracts. This comparison highlights some of the key differences between renewable and natural gas generation that decision makers should consider when making electricity investment and contracting decisions. Our assessment is relevant in both regulated and restructured markets. In still-regulated markets, the audience for this report clearly includes regulators and the utilities they

  1. Investigation of animal and algal bioassays for reliable saxitoxin ecotoxicity and cytotoxicity risk evaluation.

    Science.gov (United States)

    Perreault, François; Matias, Marcelo Seleme; Melegari, Silvia Pedroso; Pinto, Catia Regina Silva de Carvalho; Creppy, Edmond Ekué; Popovic, Radovan; Matias, William Gerson

    2011-05-01

    Contamination of water bodies by saxitoxin can result in various toxic effects in aquatic organisms. Saxitoxin contamination has also been shown to be a threat to human health in several reported cases, even resulting in death. In this study, we evaluated the sensitivity of animal (Neuro-2A) and algal (Chlamydomonas reinhardtii) bioassays to saxitoxin effect. Neuro-2A cells were found to be sensitive to saxitoxin, as shown by a 24 h EC50 value of 1.5 nM, which was obtained using a cell viability assay. Conversely, no saxitoxin effect was found in any of the algal biomarkers evaluated, for the concentration range tested (2-128 nM). These results indicate that saxitoxin may induce toxic effects in animal and human populations at concentrations where phytoplankton communities are not affected. Therefore, when evaluating STX risk of toxicity, algal bioassays do not appear to be reliable indicators and should always be conducted in combination with animal bioassays. Copyright © 2011 Elsevier Inc. All rights reserved.

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

    International Nuclear Information System (INIS)

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

    2009-01-01

    Since the Reactor Safety Study in the early 1970's, human reliability analysis (HRA) has been evolving towards a better ability to account for the factors and conditions that can lead humans to take unsafe actions and thereby provide better estimates of the likelihood of human error for probabilistic risk assessments (PRAs). The purpose of this paper is to provide an overview of recent reviews of operational events and advances in the behavioral sciences that have impacted the evolution of HRA methods and contributed to improvements. The paper discusses the importance of human errors in complex human-technical systems, examines why humans contribute to accidents and unsafe conditions, and discusses how lessons learned over the years have changed the perspective and approach for modeling human behavior in PRAs of complicated domains such as nuclear power plants. It is argued that it has become increasingly more important to understand and model the more cognitive aspects of human performance and to address the broader range of factors that have been shown to influence human performance in complex domains. The paper concludes by addressing the current ability of HRA to adequately predict human failure events and their likelihood

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

    Energy Technology Data Exchange (ETDEWEB)

    Bley, Dennis C. (Buttonwood Consulting Inc., Oakton, VA); Lois, Erasmia (U.S. Nuclear Regulatory Commission, Washington, DC); Kolaczkowski, Alan M. (Science Applications International Corporation, Eugene, OR); Forester, John Alan; Wreathall, John (John Wreathall and Co., Dublin, OH); Cooper, Susan E. (U.S. Nuclear Regulatory Commission, Washington, DC)

    2009-01-01

    Since the Reactor Safety Study in the early 1970's, human reliability analysis (HRA) has been evolving towards a better ability to account for the factors and conditions that can lead humans to take unsafe actions and thereby provide better estimates of the likelihood of human error for probabilistic risk assessments (PRAs). The purpose of this paper is to provide an overview of recent reviews of operational events and advances in the behavioral sciences that have impacted the evolution of HRA methods and contributed to improvements. The paper discusses the importance of human errors in complex human-technical systems, examines why humans contribute to accidents and unsafe conditions, and discusses how lessons learned over the years have changed the perspective and approach for modeling human behavior in PRAs of complicated domains such as nuclear power plants. It is argued that it has become increasingly more important to understand and model the more cognitive aspects of human performance and to address the broader range of factors that have been shown to influence human performance in complex domains. The paper concludes by addressing the current ability of HRA to adequately predict human failure events and their likelihood.

  4. Proceedings of the Canadian Institute's 3. annual conference on generation adequacy in Ontario : strategies to increase capacity to ensure a reliable electricity supply in Ontario

    International Nuclear Information System (INIS)

    2006-01-01

    This conference provided a forum for the discussion of issues related to generation adequacy in Ontario. Members of the electricity industry as well as members from governmental and non-governmental agencies discussed a variety of recommendations for cost-effective reliable energy in Ontario. Issues related to the overhaul or replacement of nuclear power reactors and coal-fired generators in the province were reviewed. The status of various wind power projects in the province was examined along with issues related to interconnected power systems. Best practices for the planning and execution of electricity infrastructure projects were also reviewed, and issues related to stakeholder involvement in electricity generation projects were discussed. The discussions also described recent developments in electricity generation in various jurisdictions in Canada and the United States. The conference featured 19 presentations, of which 7 have been catalogued separately for inclusion in this database. tabs., figs

  5. Electric-stress reliability and current collapse of different thickness SiNx passivated AlGaN/GaN high electron mobility transistors

    International Nuclear Information System (INIS)

    Ling, Yang; Gui-Zhou, Hu; Yue, Hao; Xiao-Hua, Ma; Si, Quan; Li-Yuan, Yang; Shou-Gao, Jiang

    2010-01-01

    This paper investigates the impact of electrical degradation and current collapse on different thickness SiN x passivated AlGaN/GaN high electron mobility transistors. It finds that higher thickness SiN x passivation can significantly improve the high-electric-field reliability of a device. The degradation mechanism of the SiN x passivation layer under ON-state stress has also been discussed in detail. Under the ON-state stress, the strong electric-field led to degradation of SiN x passivation located in the gate-drain region. As the thickness of SiN x passivation increases, the density of the surface state will be increased to some extent. Meanwhile, it is found that the high NH 3 flow in the plasma enhanced chemical vapour deposition process could reduce the surface state and suppress the current collapse. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  6. The Risk of Residential Peak Electricity Demand: A Comparison of Five European Countries

    Directory of Open Access Journals (Sweden)

    Jacopo Torriti

    2017-03-01

    Full Text Available The creation of a Europe-wide electricity market combined with the increased intermittency of supply from renewable sources calls for an investigation into the risk of aggregate peak demand. This paper makes use of a risk model to assess differences in time-use data from residential end-users in five different European electricity markets. Drawing on the Multinational Time-Use Survey database, it assesses risk in relation to the probability of electrical appliance use within households for five European countries. Findings highlight in which countries and for which activities the risk of aggregate peak demand is higher and link smart home solutions (automated load control, dynamic pricing and smart appliances to different levels of peak demand risk.

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

    International Nuclear Information System (INIS)

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

    2005-01-01

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

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

    Science.gov (United States)

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

    2017-03-03

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

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

    Science.gov (United States)

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

    1997-08-01

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

  10. Effect of Heat and Electricity Storage and Reliability on Microgrid Viability:A Study of Commercial Buildings in California and New York States

    Energy Technology Data Exchange (ETDEWEB)

    Stadler, Michael; Marnay, Chris; Siddiqui, Afzal; Lai, Judy; Coffey, Brian; Aki, Hirohisa

    2008-12-01

    In past work, Berkeley Lab has developed the Distributed Energy Resources Customer Adoption Model (DER-CAM). Given end-use energy details for a facility, a description of its economic environment and a menu of available equipment, DER-CAM finds the optimal investment portfolio and its operating schedule which together minimize the cost of meeting site service, e.g., cooling, heating, requirements. Past studies have considered combined heat and power (CHP) technologies. Methods and software have been developed to solve this problem, finding optimal solutions which take simultaneity into account. This project aims to extend on those prior capabilities in two key dimensions. In this research storage technologies have been added as well as power quality and reliability (PQR) features that provide the ability to value the additional indirect reliability benefit derived from Consortium for Electricity Reliability Technology Solutions (CERTS) Microgrid capability. This project is intended to determine how attractive on-site generation becomes to a medium-sized commercial site if economical storage (both electrical and thermal), CHP opportunities, and PQR benefits are provided in addition to avoiding electricity purchases. On-site electrical storage, generators, and the ability to seamlessly connect and disconnect from utility service would provide the facility with ride-through capability for minor grid disturbances. Three building types in both California and New York are assumed to have a share of their sensitive electrical load separable. Providing enhanced service to this load fraction has an unknown value to the facility, which is estimated analytically. In summary, this project began with 3 major goals: (1) to conduct detailed analysis to find the optimal equipment combination for microgrids at a few promising commercial building hosts in the two favorable markets of California and New York; (2) to extend the analysis capability of DER-CAM to include both heat and

  11. Assessment of risk factors for death in electrical injury.

    Science.gov (United States)

    Dokov, William

    2009-02-01

    Fatal high-voltage injuries present a problem which has not yet been studied sufficiently in the context of interaction between the human body and electricity, as a technical, anthropogenic and natural phenomenon. The forensic medicine records of 291 cases of death caused by high-voltage current for a 41-year-long period (1965-2006) were examined in retrospect. The descriptive statistical analyses were made using the SPSS 11.0 software. Death was found to result most commonly from contact between the deceased and elements of the power transmission and distribution grid: (41.24%), and from the action of lightning: (32.3%), the difference in their relative share being insignificant. Much more rarely, death was due to contact with construction and repair electrical devices: (7.56%), or with elements of the power transport railway infrastructure: (6.87%). Death resulting from contact with agricultural electrical devices was only occasional: (0.68%). The victims' average age was 36.19 years. Our analysis indicates that the relative share (43.98%) of the victims is the highest in the age period between 25 and 44. The ratio between women and men is 1:21.38.

  12. Innovative protection and control systems for a reliable and secure operation of electrical transmission systems; Innovative Schutz- und Leitsysteme zur zuverlaessigen und sicheren elektrischen Energieuebertragung

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, Sven C.; Kubis, Adreas; Rehtanz, Christian [Technische Univ. Dortmund (Germany). Inst. fuer Energiesysteme, Energieeffizienz und Energiewirtschaft (ie3); Brato, Sebastian; Goetze, Juergen [Technische Univ. Dortmund (Germany). Arbeitsgebiet Datentechnik

    2012-07-01

    The integration of European electricity markets as well as the increasing power feed-in by renewable energy sources pose new challenges to the operation of electrical transmission systems. Modern protection and control systems based on wide-area information can substantially contribute to a reliable and secure system operation even against the background of future demands. In this paper research advances regarding new applications for wide-area monitoring, protection and control as well as an integrated simulation for power and ICT systems are presented that have been developed in the course of DFG research unit FOR1511 at TU Dortmund. (orig.)

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

    Science.gov (United States)

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

    2014-12-13

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

  14. Investigation into the risk perceptions of investors in the securities of nuclear-dependent electric utilities

    International Nuclear Information System (INIS)

    Spudeck, R.E.

    1983-01-01

    Two weeks prior to the Three Mile Island accident, March 15, 1979, the Nuclear Regulatory Commission ordered five operating nuclear plants shut down in order to reexamine safety standards in these plants. Reports in the popular and trade press during this time suggested that these events, particularly the accident at Three Mile Island, caused investors in the securities of electric utilities that had nuclear-generation facilities to revise their risk perceptions. This study was designed to examine the impact of both the Nuclear Regulatory Commission order and the accident at Three Mile Island on investor risk perceptions. Selected categories of electric utilities were chosen to examine any differential risk effects resulting from these events. An asset pricing model devoid of many of the restrictive assumptions of more familiar models was used to model investor behavior. The findings suggest that the events described did cause investors to revise upward their perceptions of systematic risk regarding different categories of electric utilities. More specifically, those electric utilities that were operating nuclear plants in 1979 experienced the largest and most sustained increase in systematic risk. However, electric utilities that in 1979 had no operating nuclear plants, but had planned and committed funds for nuclear plants in the future, also experienced increases in systematic risk

  15. Evaluation of allowed outage times (AOTS) from a risk and reliability standpoint

    International Nuclear Information System (INIS)

    Vesely, W.E.

    1989-08-01

    This report describes the basic risks associated with allowed outage times (AOTS), defines strategies for selecting the risks to be quantified, and describes how the risks can be quantified. This report provides a basis for risk-based approaches for regulatory and plant implementation. The AOT risk evaluations can be applied to proposed one-time AOT changes, or to permanent changes. The evaluations can also be used to quantify risks associated with present AOTs, and in establishing AOTs from a risk perspective. The report shows that the standard way of calculating AOT risks in probabilistic risk analyses (PRAs) generally is not sufficient when evaluating all the risks associated with an AOT in order to assess its acceptability. The PRA calculates an average AOT risk which includes the frequency at which the AOT is expected to occur. Other risks associated with an AOT include the single downtime risk, which is the risk incurred when (given) the AOT has occurred. The single downtime risk is generally the most applicable risk in determining the acceptability of the AOT. The single downtime risks are generally much larger than the PRA-averaged risk. For more comprehensive evaluations, both risks should be calculated. The report also describes other risks which can be considered, including personnel and economic risks. Finally, the report discusses the detailed evaluations which are involved in calculating AOT risks, including considerations of uncertainty. (author)

  16. Market price of risk implied by Asian-style electricity options and futures

    Energy Technology Data Exchange (ETDEWEB)

    Weron, Rafal [Hugo Steinhaus Center for Stochastic Methods, Institute of Mathematics and Computer Science, Wroclaw University of Technology, 50-370 Wroclaw (Poland)

    2008-05-15

    In this paper we propose a jump-diffusion type model which recovers the main characteristics of electricity spot price dynamics in the Nordic market, including seasonality, mean-reversion and spiky behavior. We show how the calibration of the market price of risk to actively traded futures contracts allows for efficient valuation of Nord Pool's Asian-style options written on the spot electricity price. Furthermore, we study the evolution of the market price of risk (and the risk premium) over a three year time period and compare the obtained results with those reported in the literature. (author)

  17. Market price of risk implied by Asian-style electricity options and futures

    International Nuclear Information System (INIS)

    Weron, Rafal

    2008-01-01

    In this paper we propose a jump-diffusion type model which recovers the main characteristics of electricity spot price dynamics in the Nordic market, including seasonality, mean-reversion and spiky behavior. We show how the calibration of the market price of risk to actively traded futures contracts allows for efficient valuation of Nord Pool's Asian-style options written on the spot electricity price. Furthermore, we study the evolution of the market price of risk (and the risk premium) over a three year time period and compare the obtained results with those reported in the literature. (author)

  18. Reliability of power system with open access

    International Nuclear Information System (INIS)

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

    2003-01-01

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

  19. Electric vehicle (EV) storage supply chain risk and the energy market: A micro and macroeconomic risk management approach

    Science.gov (United States)

    Aguilar, Susanna D.

    As a cost effective storage technology for renewable energy sources, Electric Vehicles can be integrated into energy grids. Integration must be optimized to ascertain that renewable energy is available through storage when demand exists so that cost of electricity is minimized. Optimization models can address economic risks associated with the EV supply chain- particularly the volatility in availability and cost of critical materials used in the manufacturing of EV motors and batteries. Supply chain risk can reflect itself in a shortage of storage, which can increase the price of electricity. We propose a micro-and macroeconomic framework for managing supply chain risk through utilization of a cost optimization model in combination with risk management strategies at the microeconomic and macroeconomic level. The study demonstrates how risk from the EVs vehicle critical material supply chain affects manufacturers, smart grid performance, and energy markets qualitatively and quantitatively. Our results illustrate how risk in the EV supply chain affects EV availability and the cost of ancillary services, and how EV critical material supply chain risk can be mitigated through managerial strategies and policy.

  20. Deregulation in the electricity sector: Understanding strategic and regulatory risk

    Energy Technology Data Exchange (ETDEWEB)

    Larsen, E.R. [City Univ. Business School, Dept. Management Systems and Information, London (United Kingdom); Bunn, D.W. [London Business School, London (United Kingdom)

    1999-08-01

    This paper is motivated by our experiences since 1990 with developing system simulation models to help UK companies in the restructured electricity industry understand the radically different market within which they must become competitive. When public utilities such as electricity have been restructured, deregulated and/or privatised, the process has often been associated with a major change in the competitive environment. As a consequence, the strategic and regulatory uncertainties ahead for these companies are unprecedented. In such a market there has been no historical evolution and all the participants including the regulatory institutions have very little understanding of how it will operate in the short term and evolve in the future. In this situation, the use of systems dynamic models appears to offer an attractive way of gaining insights into how aspects of the competitive market might evolve. In the absence of real experience and relevant analogies, learning from models assumes a key role. Such models cannot be validated empirically, but can be developed to represent how the system is designed to operate. From such a prototypical basis, sensitivity analysis can generate insights on the strategic opportunities created failings in the market design, or its potential instability to shocks and market imperfections. (au)

  1. A case study review of technical and technology issues for transition of a utility load management program to provide system reliability resources in restructured electricity markets

    Energy Technology Data Exchange (ETDEWEB)

    Weller, G.H.

    2001-07-15

    Utility load management programs--including direct load control and interruptible load programs--were employed by utilities in the past as system reliability resources. With electricity industry restructuring, the context for these programs has changed; the market that was once controlled by vertically integrated utilities has become competitive, raising the question: can existing load management programs be modified so that they can effectively participate in competitive energy markets? In the short run, modified and/or improved operation of load management programs may be the most effective form of demand-side response available to the electricity system today. However, in light of recent technological advances in metering, communication, and load control, utility load management programs must be carefully reviewed in order to determine appropriate investments to support this transition. This report investigates the feasibility of and options for modifying an existing utility load management system so that it might provide reliability services (i.e. ancillary services) in the competitive markets that have resulted from electricity industry restructuring. The report is a case study of Southern California Edison's (SCE) load management programs. SCE was chosen because it operates one of the largest load management programs in the country and it operates them within a competitive wholesale electricity market. The report describes a wide range of existing and soon-to-be-available communication, control, and metering technologies that could be used to facilitate the evolution of SCE's load management programs and systems to provision of reliability services. The fundamental finding of this report is that, with modifications, SCE's load management infrastructure could be transitioned to provide critical ancillary services in competitive electricity markets, employing currently or soon-to-be available load control technologies.

  2. Residential PV system users' perception of profitability, reliability, and failure risk: An empirical survey in a local Japanese municipality

    International Nuclear Information System (INIS)

    Mukai, Toshihiro; Kawamoto, Shishin; Ueda, Yuzuru; Saijo, Miki; Abe, Naoya

    2011-01-01

    Although previous studies have addressed the reliability of residential PV systems in order to improve the dissemination of the systems among individual users and societies, few have examined users' perception of their own PV systems, which might contain solutions to firmly establish the system into society. First, the present paper examined the extent to which residential PV system users understand specification, reliability, and failure risk of their own systems. Second, causal factors affecting users' satisfaction with PV systems were examined. By analyzing data collected in Kakegawa City, this paper revealed that users did not appropriately understand the basic specifications of their residential PV systems, and in particular, the fact that the systems sometimes failed and therefore needed proper maintenance. Furthermore, a strong causal relationship between users' expectations of financial return from the system and their level of satisfaction was confirmed empirically. These results suggested that excessive focus on profitability and relatively low interest in the systems' reliability and failure risk should be addressed more to avoid problems that could potentially hamper the establishment of this technology into society. - Highlights: → We examined PV users' perception of its specification, reliability, and failure risk. → Data for analysis were collected by questionnaire survey in a Japanese local municipality. → We revealed users did not appropriately understand the basic specifications. → A strong causal relationship between users' expectations of financial return and their level of satisfaction was confirmed empirically.

  3. Degree of Fault Tolerance as a Comprehensive Parameter for Reliability Evaluation of Fault Tolerant Electric Traction Drives

    Directory of Open Access Journals (Sweden)

    Igor Bolvashenkov

    2016-09-01

    Full Text Available This paper describes a new approach and methodology of quantitative assessment of the fault tolerance of electric power drive consisting of the multi-phase traction electric motor and multilevel electric inverter. It is suggested to consider such traction drive as a system with several degraded states. As a comprehensive parameter for evaluating of the fault tolerance, it is proposed to use the criterion of degree of the fault tolerance. For the approbation of the proposed method, the authors carried out research and obtained results of its practical application for evaluating the fault tolerance of the power train of an electrical helicopter.

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

    Science.gov (United States)

    Komarov, Yu. A.

    2014-10-01

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

  5. Seismic risk analysis for General Electric Plutonium Facility, Pleasanton, California

    International Nuclear Information System (INIS)

    1978-01-01

    This report presents the results of a seismic risk analysis that focuses on all possible sources of seismic activity, with the exception of the postulated Verona Fault. The best estimate curve indicates that the Vallecitos facility will experience 30% g with a return period of roughly 130 years and 60% g with a return period of roughly 700 years

  6. Evaluation of nodal reliability risk in a deregulated power system with photovoltaic power penetration

    DEFF Research Database (Denmark)

    Zhao, Qian; Wang, Peng; Goel, Lalit

    2014-01-01

    Owing to the intermittent characteristic of solar radiation, power system reliability may be affected with high photovoltaic (PV) power penetration. To reduce large variation of PV power, additional system balancing reserve would be needed. In deregulated power systems, deployment of reserves...... and customer reliability requirements are correlated with energy and reserve prices. Therefore a new method should be developed to evaluate the impacts of PV power on customer reliability and system reserve deployment in the new environment. In this study, a method based on the pseudo-sequential Monte Carlo...... simulation technique has been proposed to evaluate the reserve deployment and customers' nodal reliability with high PV power penetration. The proposed method can effectively model the chronological aspects and stochastic characteristics of PV power and system operation with high computation efficiency...

  7. Human reliability

    International Nuclear Information System (INIS)

    Embrey, D.E.

    1987-01-01

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

  8. 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...

  9. Coping with nuclear power risks: the electric utility incentives

    International Nuclear Information System (INIS)

    Starr, C.; Whipple, C.

    1982-01-01

    The financial risks associated with nuclear power accidents are estimated by interpolating between frequency-vs.-severity data from routine outages and the frequency-vs.-severity estimates from the Nuclear Regulatory Commission's (NRC's) Reactor Safety Study (WASH-1400). This analysis indicates that the expected costs of plant damage and lost power production are large compared to the public risks estimated in WASH-1400, using values from An Approach to Quantitative Safety Goals for Nuclear Power Plants (NUREG-0739), prepared by the NRC Advisory Committee on Reactor Safeguards. Analyses of the cost-effectiveness of accident-prevention investments that include only anticipated public safety benefits will underestimate the value of such investments if reductions in power plant damage risk are not included. The analysis also suggests that utility self-interest and the public interest in safety are generally coincident. It is argued that greater use could be made of this self-interest in regulation if the relationship between the NRC and the industry were more cooperative, less adversary in nature

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

    International Nuclear Information System (INIS)

    Lofgren, E.V.

    1985-08-01

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

  11. Reallocating risks and returns to scale up adoption of distributed electricity resources

    International Nuclear Information System (INIS)

    Kulatilaka, Nalin; Santiago, Leonardo; Vakili, Pirooz

    2014-01-01

    Deployment of distributed electricity resources requires bringing together assets that belong to diverse and geographically diffuse owners. Using the example of distributed solar PV, we analyze the schemes used to encourage/induce owners of distributed assets to make them available for electricity generation. The dominant model in the U.S. is long term power purchase agreements (PPA) offered to owners/consumers by solar developers. We show that these agreements (mis)allocate the electricity price risk to owners/consumers and impose limitations on the scale up of distributed solar. By proper use of financial markets it is possible to shift the electricity price risk from owners/consumers to parties that are better positioned to manage it. The proposed contracts simplify the adoption decision for owners/consumers and can lead to a wider adoption. Removing barriers to scale up requires (i) eliminating the tight coupling between consumers and owners and (ii) rewarding the owners unambiguously for the assets they provide. These necessitate the transformation of the current intermediary firms into full-fledged distributed generators. We discuss the implications of such a transformation and argue that the broad outline of our analysis can be used to assess scale up schemes in other domains of distributed electricity resources as well. - Highlights: • We analyze schemes used to induce owners of distributed assets to make them available for electricity generation. • We show that power purchase agreements used in solar PV “misallocate” electricity price risk to owners/consumers. • We propose new contracts forms that shift price risk from consumers to parties that are better able to manage it. • Full-fledged distributed generators are created by unambiguously rewarding owners and de-coupling consumption/ownership. • We argue that our analysis can be used to assess scale up schemes in other domains of distributed electricity resources

  12. Economic risks of the capacity expansion of electric power generation: impact of the nuclear energy

    International Nuclear Information System (INIS)

    Nieva G, R.

    2009-01-01

    Uncertainty and risks are inherent to the electric systems planning. The long period of construction that is characteristic of the electric sector works, as well as the long useful life of the generation assets and electric power transmission, they force to plan the expansion of the electric systems along horizons from 10 to 25 years. In periods so long of time it is impossible to predict with certainty the elements of the environment that could influence in the taking of decisions, like they are: the growth and the distribution of the electric power demand, the readiness and fuel prices; the investment costs of the technological options of generation and transmission, as well as the duration of the construction of future projects of new capacity addition. All expansion plan that will be propose, will be exposed to the uncertainty of the environment, gives place to risks or undesirable consequences. The nature of the risks, the strategies to delimit them and the outlines to assign them between the different interested parts and the diverse economic agents, depend in great measure of the legal and normative mark of the sector. In this work these topics are approached inside the reference mark of the Mexican public service of electric power. (Author)

  13. Use of electric bedding devices and risk of breast cancer in African-American women.

    Science.gov (United States)

    Zhu, Kangmin; Hunter, Sandra; Payne-Wilks, Kathleen; Roland, Chanel L; Forbes, Digna S

    2003-10-15

    In this case-control study, the authors aimed to examine whether use of an electric bedding device increased breast cancer risk in African-American women. Cases were 304 African-American patients diagnosed with breast cancer during 1995-1998 who were aged 20-64 years and lived in one of three Tennessee counties. Controls were 305 African-American women without breast cancer who were selected through random digit dialing and frequency-matched to cases by age and county. Information on the use of an electric blanket or heated water bed and other risk factors was collected through telephone interviews. Breast cancer risk associated with use of an electric bedding device increased with the number of years of use, the number of seasons of use, and the length of time of use during sleep. When women who used an electric bedding device for more than 6 months per year (and therefore were more likely to have used a heated water bed, which generates lower magnetic fields) were excluded, the corresponding dose-response relations were more striking. Similar trends in dose response were shown in both premenopausal and postmenopausal women and for both estrogen receptor-positive and estrogen receptor-negative tumors. The use of electric bedding devices may increase breast cancer risk in African-American women aged 20-64 years. Such an association might not vary substantially by menopausal status or estrogen receptor status.

  14. Electricity

    CERN Document Server

    Basford, Leslie

    2013-01-01

    Electricity Made Simple covers the fundamental principles underlying every aspect of electricity. The book discusses current; resistance including its measurement, Kirchhoff's laws, and resistors; electroheat, electromagnetics and electrochemistry; and the motor and generator effects of electromagnetic forces. The text also describes alternating current, circuits and inductors, alternating current circuits, and a.c. generators and motors. Other methods of generating electromagnetic forces are also considered. The book is useful for electrical engineering students.

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

    Science.gov (United States)

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

    2016-10-01

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

  16. The Electricity Feed Law levy - how reliably can it be predicted?; Wie verlaesslich laesst sich die EEG-Umlage prognostizieren?

    Energy Technology Data Exchange (ETDEWEB)

    Bause, Rainer; Schulz, Woldemar [Amprion GmbH, Dortmund (Germany); Buehler, Holger [EnBW TNG, Stuttgart (Germany); Hodurek, Claus [50Hertz Transmission GmbH, Berlin (Germany); Kiessling, Axel [TenneT TSO GmbH, Bayreuth (Germany)

    2011-10-15

    By paying their monthly electricity bill German consumers are promoting the transition to tomorrow's resource-efficient electricity supply system, in which the largest part of electricity used is to come from renewable energy resources. Every year Germany's transmission system operators publish what is referred to as the ''EEG-Umlage'' (report on the Electricity Feed Law levy, or EEG levy), which shows how much every German household will be paying for the promotion of renewable energies in the coming year. The determination of the EEG levy involves uncertainties and imponderabilities which have to be taken into account in its calculation. The crucial task is to find a suitable systematic scheme for predicting the renewable energy yield.

  17. Risks, revenues and investment in electricity generation. Why policy needs to look beyond costs

    International Nuclear Information System (INIS)

    Gross, Robert; Heptonstall, Philip; Blyth, William

    2010-01-01

    Energy policy goals frequently depend upon investment in particular technologies, or categories of technology. Whilst the British government has often espoused the virtues of technological neutrality, UK policies now seek to promote nuclear power, coal with CO 2 capture and storage, and renewable energy. Policy decisions are often informed by estimates of cost per unit of output (for example, pound /MWh), also known as levelised costs. Estimates of these costs for different technologies are often used to provide a 'ballpark' guide to the levels of financial support needed (if any) to encourage uptake, or direct investment away from the technologies the market might otherwise have chosen. Levelised cost estimates can also help to indicate the cost of meeting public policy objectives, and whether there is a rationale for intervention (for example, based on net welfare gains). In the UK electricity sector, investment is undertaken by private companies, not governments. Investment is driven by expected returns, in the light of a range of risks related to both costs and revenues. Revenue risks are not captured in estimates of cost or cost-related risks. An important category of revenue risk is associated with electricity price fluctuations. Exposure to price risks differs by technology. Low electricity prices represent a revenue risk to technologies that cannot influence electricity prices. By contrast, 'price makers' that set marginal prices are, to an extent, able to pass fuel price increases through to consumers. They have an inherent 'hedge' against fuel and electricity price fluctuations. Based on recent research by the UK Energy Research Centre, this paper considers the implications of such price risks for policy design. The authors contrast the range of levelised costs estimated for different generating options with the spread of returns each is exposed to when electricity price fluctuations are factored in. Drawing on recent policy experiences in the renewable

  18. Integrating renewable energy technologies in the electric supply industry: A risk management approach

    Energy Technology Data Exchange (ETDEWEB)

    Hoff, T.E. [Pacific Energy Group, Walnut Creek, CA (United States)

    1997-07-01

    Regulatory and technical forces are causing electric utilities to move from a natural monopoly to a more competitive environment. Associated with this movement is an increasing concern about how to manage the risks associated with the electric supply business. One approach to managing risks is to purchase financial instruments such as options and futures contracts. Another approach is to own physical assets that have low risk attributes or characteristics. This research evaluates how investments in renewable energy technologies can mitigate risks in the electric supply industry. It identifies risks that are known to be of concern to utilities and other power producers. These risks include uncertainty in fuel prices, demand, environmental regulations, capital cost, supply, and market structure. The research then determines how investments in renewables can mitigate these risks. Methods are developed to calculate the value of renewables in terms of their attributes of fuel costs, environmental costs, lead-time, modularity, availability, initial capital costs, and investment reversibility. Examples illustrate how to apply the methods.

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

    Science.gov (United States)

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

    2018-01-01

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

  20. Electrical Performance and Reliability Improvement of Amorphous-Indium-Gallium-Zinc-Oxide Thin-Film Transistors with HfO2 Gate Dielectrics by CF4 Plasma Treatment

    Science.gov (United States)

    Fan, Ching-Lin; Tseng, Fan-Ping; Tseng, Chiao-Yuan

    2018-01-01

    In this work, amorphous indium-gallium-zinc oxide thin-film transistors (a-IGZO TFTs) with a HfO2 gate insulator and CF4 plasma treatment was demonstrated for the first time. Through the plasma treatment, both the electrical performance and reliability of the a-IGZO TFT with HfO2 gate dielectric were improved. The carrier mobility significantly increased by 80.8%, from 30.2 cm2/V∙s (without treatment) to 54.6 cm2/V∙s (with CF4 plasma treatment), which is due to the incorporated fluorine not only providing an extra electron to the IGZO, but also passivating the interface trap density. In addition, the reliability of the a-IGZO TFT with HfO2 gate dielectric has also been improved by the CF4 plasma treatment. By applying the CF4 plasma treatment to the a-IGZO TFT, the hysteresis effect of the device has been improved and the device’s immunity against moisture from the ambient atmosphere has been enhanced. It is believed that the CF4 plasma treatment not only significantly improves the electrical performance of a-IGZO TFT with HfO2 gate dielectric, but also enhances the device’s reliability. PMID:29772767

  1. Electrical Performance and Reliability Improvement of Amorphous-Indium-Gallium-Zinc-Oxide Thin-Film Transistors with HfO2 Gate Dielectrics by CF4 Plasma Treatment

    Directory of Open Access Journals (Sweden)

    Ching-Lin Fan

    2018-05-01

    Full Text Available In this work, amorphous indium-gallium-zinc oxide thin-film transistors (a-IGZO TFTs with a HfO2 gate insulator and CF4 plasma treatment was demonstrated for the first time. Through the plasma treatment, both the electrical performance and reliability of the a-IGZO TFT with HfO2 gate dielectric were improved. The carrier mobility significantly increased by 80.8%, from 30.2 cm2/V∙s (without treatment to 54.6 cm2/V∙s (with CF4 plasma treatment, which is due to the incorporated fluorine not only providing an extra electron to the IGZO, but also passivating the interface trap density. In addition, the reliability of the a-IGZO TFT with HfO2 gate dielectric has also been improved by the CF4 plasma treatment. By applying the CF4 plasma treatment to the a-IGZO TFT, the hysteresis effect of the device has been improved and the device’s immunity against moisture from the ambient atmosphere has been enhanced. It is believed that the CF4 plasma treatment not only significantly improves the electrical performance of a-IGZO TFT with HfO2 gate dielectric, but also enhances the device’s reliability.

  2. Electrical Performance and Reliability Improvement of Amorphous-Indium-Gallium-Zinc-Oxide Thin-Film Transistors with HfO₂ Gate Dielectrics by CF₄ Plasma Treatment.

    Science.gov (United States)

    Fan, Ching-Lin; Tseng, Fan-Ping; Tseng, Chiao-Yuan

    2018-05-17

    In this work, amorphous indium-gallium-zinc oxide thin-film transistors (a-IGZO TFTs) with a HfO₂ gate insulator and CF₄ plasma treatment was demonstrated for the first time. Through the plasma treatment, both the electrical performance and reliability of the a-IGZO TFT with HfO₂ gate dielectric were improved. The carrier mobility significantly increased by 80.8%, from 30.2 cm²/V∙s (without treatment) to 54.6 cm²/V∙s (with CF₄ plasma treatment), which is due to the incorporated fluorine not only providing an extra electron to the IGZO, but also passivating the interface trap density. In addition, the reliability of the a-IGZO TFT with HfO₂ gate dielectric has also been improved by the CF₄ plasma treatment. By applying the CF₄ plasma treatment to the a-IGZO TFT, the hysteresis effect of the device has been improved and the device's immunity against moisture from the ambient atmosphere has been enhanced. It is believed that the CF₄ plasma treatment not only significantly improves the electrical performance of a-IGZO TFT with HfO₂ gate dielectric, but also enhances the device's reliability.

  3. A Quantitative Risk Analysis Framework for Evaluating and Monitoring Operational Reliability of Cloud Computing

    Science.gov (United States)

    Islam, Muhammad Faysal

    2013-01-01

    Cloud computing offers the advantage of on-demand, reliable and cost efficient computing solutions without the capital investment and management resources to build and maintain in-house data centers and network infrastructures. Scalability of cloud solutions enable consumers to upgrade or downsize their services as needed. In a cloud environment,…

  4. Reliability and availability analyses (as a basis for a simplified risk assessment) in HTR power stations

    International Nuclear Information System (INIS)

    Hinrichs

    1976-01-01

    The fault tree analysis is essentially used with HRB to investigate the failure behaviour of systems, and the characteristic reliability parameters are determined with simulation computer programmes. As the methods and auxiliary means have been given in an earlier report, only concrete studies and application examples are presented here. (RW/LH) [de

  5. Some recent developments in the risk- and reliability analysis of structures

    International Nuclear Information System (INIS)

    Bauer, J.; Choi, H.S.; Kappler, H.; Melzer, H.J.; Panggabean, H.; Reichmann, K.H.; Schueller, G.I.; Schwarz, R.F.

    1979-01-01

    This report consists of six contributions divided into four general topics. While Part I concentrates on the development of Analytical Methods in Structural Reliability, Part II to IV are devoted to the application of these methods to Offshore-, Nuclear - and generally to Wind- and Earthquake Exposed Structures. (orig.) [de

  6. Project finance risk evaluation of the Electric power industry of Serbia

    International Nuclear Information System (INIS)

    Makajic Nikolic, Dragana; Jednak, Sandra; Benkovic, Sladana; Poznanic, Vladimir

    2011-01-01

    From the aspect of the development of a country, the energy sector represents a domain of strategic interest. Generation and use of energy resources most often belongs to the public sector, and are most often under the influence of the government in most countries. This paper analyzes the risks that are characteristic to the business of the public enterprise, Electric Power Industry of Serbia (EPS). EPS has started its restructuring and is adjusting to changes and challenges imposed by the launched reforms in the energy sector. However, due to certain limitations, it is still not possible to implement its complete restructuring and modernization. The paper aims to point at the risks a potential strategic partner faces. The risks have been identified as commercial, financial and political, classification immanent for project finance, and their evaluation was done using Failure Mode and Effects Analysis (FMEA). Risk analysis was performed based on current conditions for two potential scenarios that predict different types of changes in the analyzed period. The results of the analysis show that the potential strategic partner should pay special attention to price risks, estimation, investments, project activity neglect, quasi-risks and debt collection. - Highlights: → Paper analyze all risks characteristic for business running of the public enterprise EPS. → Potential strategic partner faces with the commercial, financial and political risks. → Risk analysis was done using FMEA. → Results are indicating high risk of investing in EPS. → The highest risks are commercial risks, especially price risks.

  7. System for the reliability analysis of the electric energy supply; Sistema para el analisis de confiabilidad del suministro de energia electrica

    Energy Technology Data Exchange (ETDEWEB)

    Perales, Favio; Martinez, Javier; Huesca, Francisco; Garcia, Norma; Nieva, Rolando [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1997-12-31

    A computer tool, developed for the reliability evaluation of the electric energy supply, considering the faults in the generation and transmission systems, is presented. The application of the tool in planning the expansion and operation of the electric systems, the methodology of the solution employed and the various functions it accounts for, are described. At the end some illustrative examples of its applications by means of the studies with a model of representative characteristics of the interconnected national system. [Espanol] Se presenta una herramienta computacional desarrollada para evaluar la confiabilidad del suministro de energia electrica, considerando las fallas en los sistemas de generacion y transmision. Se describen las aplicaciones de la herramienta en la planeacion de la expansion y de la operacion de sistemas electricos, la metodologia de solucion empleada y las diversas funciones con que cuenta. Al final se presentan algunos ejemplos ilustrativos de sus aplicaciones mediante estudios con un modelo de caracteristicas representativas del sistema interconectado nacional.

  8. System for the reliability analysis of the electric energy supply; Sistema para el analisis de confiabilidad del suministro de energia electrica

    Energy Technology Data Exchange (ETDEWEB)

    Perales, Favio; Martinez, Javier; Huesca, Francisco; Garcia, Norma; Nieva, Rolando [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1998-12-31

    A computer tool, developed for the reliability evaluation of the electric energy supply, considering the faults in the generation and transmission systems, is presented. The application of the tool in planning the expansion and operation of the electric systems, the methodology of the solution employed and the various functions it accounts for, are described. At the end some illustrative examples of its applications by means of the studies with a model of representative characteristics of the interconnected national system. [Espanol] Se presenta una herramienta computacional desarrollada para evaluar la confiabilidad del suministro de energia electrica, considerando las fallas en los sistemas de generacion y transmision. Se describen las aplicaciones de la herramienta en la planeacion de la expansion y de la operacion de sistemas electricos, la metodologia de solucion empleada y las diversas funciones con que cuenta. Al final se presentan algunos ejemplos ilustrativos de sus aplicaciones mediante estudios con un modelo de caracteristicas representativas del sistema interconectado nacional.

  9. IMPROVING THE RELIABILITY OF THE POWER CIRCUIT OF THE ELECTRIC TRAINS ЕР2Т AND ЕПЛ2Т

    Directory of Open Access Journals (Sweden)

    N. H. Visin

    2010-02-01

    Full Text Available The transitional processes in shunt circuit of traction engines, which armatures and excitation windings are connected in non-conducting direction as to the flowing power current, are considered in this paper. The changes in the control circuits of braking switch and in the shunt power circuit of traction engines with additional mounting a resistor of 0.5 Ohm are proposed. All this modernization will allow increasing greatly the operation reliability of power circuit of ЭР2Т and ЕПЛ2Т electric locomotives during their service life.

  10. Hybrid instrument applied to human reliability study in event of loss of external electric power in a nuclear power plant; Instrumento hibrido aplicado ao estudo da confiabilidade humana em evento de perda de energia eletrica externa em usina nuclear

    Energy Technology Data Exchange (ETDEWEB)

    Martins, Eduardo Ferraz

    2015-04-01

    The study projects in highly complex installations involves robust modeling, supported by conceptual and mathematical tools, to carry out systematic research and structured the different risk scenarios that can lead to unwanted events from occurring equipment failures or human errors. In the context of classical modeling, the Probabilistic Safety Analysis (PSA) seeks to provide qualitative and quantitative information about the project particularity and their operational facilities, including the identification of factors or scenarios that contribute to the risk and consequent comparison options for increasing safety. In this context, the aim of the thesis is to develop a hybrid instrument (CPP-HI) innovative, from the integrated modeling techniques of Failure Mode and Effect Analysis (FMEA), concepts of Human Reliability Analysis and Probabilistic Composition of Preferences (PCP). In support of modeling and validation of the CPP-HI, a simulation was performed on a triggering event 'Loss of External Electric Power' - PEEE, in a Nuclear Power plant. The results were simulated in a virtual environment (sensitivity analysis) and are robust to the study of Human Reliability Analysis (HRA) in the context of the PSA. (author)

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

    Science.gov (United States)

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

    2018-01-01

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

  12. Scenario based approach to structural damage detection and its value in a risk and reliability perspective

    DEFF Research Database (Denmark)

    Hovgaard, Mads Knude; Hansen, Jannick Balleby; Brincker, Rune

    2013-01-01

    A scenario- and vibration based structural damage detection method is demonstrated though simulation. The method is Finite Element (FE) based. The value of the monitoring is calculated using structural reliability theory. A high cycle fatigue crack propagation model is assumed as the damage mecha......- and without monitoring. Monte Carlo Sampling (MCS) is used to estimate the probabilities and the tower of an onshore NREL 5MW wind turbine is given as a calculation case......A scenario- and vibration based structural damage detection method is demonstrated though simulation. The method is Finite Element (FE) based. The value of the monitoring is calculated using structural reliability theory. A high cycle fatigue crack propagation model is assumed as the damage...

  13. A Look Back at the Long Path to Mandating Electric Reliability Standards through the Energy Policy Act of 2005

    Energy Technology Data Exchange (ETDEWEB)

    Young, Ellen Swyler

    2006-07-15

    The Act was the culmination of more than eight years of legislative effort in Congress. During this period, the nation saw the Western electricity crisis of 2000-01, the Sept. 11 attacks, the collapse of Enron, the growth of RTOs, and the August 2003 blackout. Each of these influenced the dynamics of the debate. (author)

  14. Low power fluorine plasma effects on electrical reliability of AlGaN/GaN high electron mobility transistor

    International Nuclear Information System (INIS)

    Yang Ling; Zhou Xiao-Wei; Ma Xiao-Hua; Lv Ling; Zhang Jin-Cheng; Hao Yue; Cao Yan-Rong

    2017-01-01

    The new electrical degradation phenomenon of the AlGaN/GaN high electron mobility transistor (HEMT) treated by low power fluorine plasma is discovered. The saturated current, on-resistance, threshold voltage, gate leakage and breakdown voltage show that each experiences a significant change in a short time stress, and then keeps unchangeable. The migration phenomenon of fluorine ions is further validated by the electron redistribution and breakdown voltage enhancement after off-state stress. These results suggest that the low power fluorine implant ion stays in an unstable state. It causes the electrical properties of AlGaN/GaN HEMT to present early degradation. A new migration and degradation mechanism of the low power fluorine implant ion under the off-stress electrical stress is proposed. The low power fluorine ions would drift at the beginning of the off-state stress, and then accumulate between gate and drain nearby the gate side. Due to the strong electronegativity of fluorine, the accumulation of the front fluorine ions would prevent the subsequent fluorine ions from drifting, thereby alleviating further the degradation of AlGaN/GaN HEMT electrical properties. (paper)

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

    International Nuclear Information System (INIS)

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

    1999-01-01

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

  16. Electric-utility returns and risk in the light of Three Mile Island

    International Nuclear Information System (INIS)

    Brooks, L.D.; D'Souza, R.E.

    1982-01-01

    The impact of the Three Mile Island nuclear-generating-unit failure on the performance of nuclear-dependent electric utilities is examined in this article. A comparative examination of the time series of abnormal returns and risk measures on nuclear-dependent utilities and nondependent utilities prior to the TMI incident, at the time of the incident, and subsequent to it was performed by the authors. The results are consistent with a hypothesis that investors associate a decline in future profitability or increased risk with nuclear-associated utilities. However, the more-objective measures indicate a clear reduction in risk for nuclear-associated utilities since the TMI incident, both in relation to the market as a whole and in relation to electric utilities which are not nuclear-associated. 4 references, 1 figure, 3 tables

  17. Predictors of electrical storm in patients with idiopathic dilated cardiomyopathy--how to stratify the risk of electrical storm.

    Science.gov (United States)

    Takigawa, Masateru; Noda, Takashi; Kurita, Takashi; Aihara, Naohiko; Yamada, Yuko; Okamura, Hideo; Satomi, Kazuhiro; Suyama, Kazuhiro; Shimizu, Wataru; Kamakura, Shiro

    2010-09-01

    Electrical storm (ES) is a serious problem in patients with an implantable cardioverter defibrillator (ICD). However, insufficient reports have indicated the predictors of ES in ICD patients with idiopathic dilated cardiomyopathy (DCM). The purpose of this study was to clarify the predictors of ES for risk stratification in DCM patients with an ICD. Of 446 ICD patients, 53 DCM patients were included in this study. During a mean follow-up of 55+/-36 months, ES (> or =3 times appropriate ICD therapy within 24 h) occurred in 18/53 (34%) patients. According to multivariate Cox proportional hazard regression analysis, a duration of the terminal low amplitude signals of <40 microV (LAS40) (HR 1.4/10 ms increase, 95% confidence interval (CI) 1.1-2.1; P=0.0049) or root mean square voltage of the last 40 ms of the QRS complex (RMS40) (HR 0.88/1 microV, 95%CI 0.77-0.96; P=0.001) on the signal averaged electrocardiogram, and a history of atrial fibrillation (AF) before ICD implantation (HR 2.3, 95%CI 1.2-5.0; P=0.013) were independently associated with an increased risk of ES. Our data indicated that a longer LAS40, lower RMS40 and history of AF before ICD implantation could strongly predict ES, and the combination of those parameters could effectively stratify the risk of ES in DCM patients.

  18. Reliability of offshore wind power production under extreme wind conditions. Deliverable D 9.5. Work Package 9: Electrical grid

    DEFF Research Database (Denmark)

    Cutululis, Nicolaos Antonio; Zeni, Lorenzo

    years, with each year simulated with five random seeds, leading to a total of 25 annual wind power time series for six large offshore wind farms, summing up to a little over 330 wind turbines. Two storm control strategies were used. The analysis involved several aspects inspired from reliability studies....... The aspects investigated are storm events occurrences and durations, storm control strategy impact on the capacity factor (lost production), the loss of production (power produced from wind drops below a certain threshold due to high wind speeds and storm controller) and finally, the wind power production......Reliability of offshore wind production under extreme wind conditions was investigated in this report. The wind power variability from existing and future large offshore wind farms in Western Denmark were simulated using the Correlated Wind model developed at Risø. The analysis was done for five...

  19. Natural gas for electric power generation: Strategic issues, risks and opportunities

    International Nuclear Information System (INIS)

    Linderman, C.

    1992-01-01

    Natural gas is again being regarded as a significant fuel for electric power generation. It was once a predominant fuel for utilities in gas-producing areas, but natural gas consumption declined greatly after the 1973 oil shock because of reduced electricity demand and increased coal and nuclear generation. Moreover, wellhead price and other forms of regulation produced gas shortages in the 1970s. The resurgence of natural gas in future resource plans stems from its inherent ideal fuel characteristics: short lead time; low capital costs; small increments of modular capacity; delivered close to load centers; environmentally benign, preferable to oil and coal; and potential for high thermal efficiency in gas turbines. Natural gas, if available and attractively priced, is an ideal fuel for electric power generation. No other fuel shares these attractive characteristics, and utilities, facing higher than expected load growth, are relying on an increasing proportion of gas-fired combustion turbines, combined cycle plants, and cogeneration to meet a growing, yet uncertain, future demand for electricity. Despite these desirable operating characteristics, the varied past and uncertain future of natural gas markets raise legitimate concerns about the riskiness of current utility natural gas strategies. This report, which summarizes the major findings from research efforts, is intended to help utility decision-makers understand the full range of risks they face with natural gas electric power generation and to identify actions they can take to mitigate those risks

  20. The evolution of electricity prices in an uncertain world. Contracting and managing the price risk

    International Nuclear Information System (INIS)

    Vassilopoulos, Ph.; Rapin, D.

    2004-01-01

    With the liberalization of the electricity market, the large industrial consumers saw their electric bill changing nature. Before, this price reflected a long term negotiation with the monopoly, now it is established in a free way via wholesale markets. This evolution marks a transfer of the management of price risk from the producer towards the consumer. This change is not in itself a problem if the hedging instruments are adapted. We note a contamination of the price of the derivative products by the spot while at the same time the traditional relation between cash and term is not always valid for electricity because of its non storability. When well even the price of the derivative products would be formed in an autonomous way, it poses a second problem: that of their indexing on price references like Platt's whose result is assimilated more to a survey of large producers than a true confrontation of supply and demand. This article proposes to examine this change of nature and behaviour of electricity prices. After having explained the intrinsically volatile characteristic of spot prices, we will recall that the products in the long term are not always optimal solutions to decrease this price risk. Lastly, we will highlight a solution of skirting at the risks mentioned above: contracting between producers and consumers. (authors)

  1. Pan-European management of electricity portfolios: Risks and opportunities of contract bundling

    International Nuclear Information System (INIS)

    Gampert, Markus; Madlener, Reinhard

    2011-01-01

    Due to the liberalization of energy markets in the European Union, today's European utilities not only focus on electricity supply, but also offer exchange-traded 'structured products' or portfolio management for unbundling financial and physical risk positions. Many utilities are only able to provide these services in their domestic markets. In a globalized economy, the need for a centrally organized pan-European portfolio management has arisen, as it allows a simplified commodity sourcing in combination with an optimized risk management. In this paper, we examine the challenges to be overcome for establishing a European-wide bundling of electricity contracts. For this purpose, a case study based on the business perspective of RWE Supply and Trading in Central and Eastern Europe is carried out. In a first step, we analyze general requirements for a pan-European bundling of electricity contracts. Then, RWE's situation in Europe is examined, based on which we finally propose a concept to meet customer demands in Central and Eastern Europe. - Research highlights: → Analysis of electricity market liberalization in Central and Eastern Europe. → Identification of requirements and problems for pan-European bundling of contracts. → Case study based on RWE Supply and Trading perspective in Central and Eastern Europe. → Model development for pan-European unbundling of financial/physical risk positions.

  2. The effect of Web-based Braden Scale training on the reliability and precision of Braden Scale pressure ulcer risk assessments.

    Science.gov (United States)

    Magnan, Morris A; Maklebust, Joann

    2008-01-01

    To evaluate the effect of Web-based Braden Scale training on the reliability and precision of pressure ulcer risk assessments made by registered nurses (RN) working in acute care settings. Pretest-posttest, 2-group, quasi-experimental design. Five hundred Braden Scale risk assessments were made on 102 acute care patients deemed to be at various levels of risk for pressure ulceration. Assessments were made by RNs working in acute care hospitals at 3 different medical centers where the Braden Scale was in regular daily use (2 medical centers) or new to the setting (1 medical center). The Braden Scale for Predicting Pressure Sore Risk was used to guide pressure ulcer risk assessments. A Web-based version of the Detroit Medical Center Braden Scale Computerized Training Module was used to teach nurses correct use of the Braden Scale and selection of risk-based pressure ulcer prevention interventions. In the aggregate, RN generated reliable Braden Scale pressure ulcer risk assessments 65% of the time after training. The effect of Web-based Braden Scale training on reliability and precision of assessments varied according to familiarity with the scale. With training, new users of the scale made reliable assessments 84% of the time and significantly improved precision of their assessments. The reliability and precision of Braden Scale risk assessments made by its regular users was unaffected by training. Technology-assisted Braden Scale training improved both reliability and precision of risk assessments made by new users of the scale, but had virtually no effect on the reliability or precision of risk assessments made by regular users of the instrument. Further research is needed to determine best approaches for improving reliability and precision of Braden Scale assessments made by its regular users.

  3. Puget Sound Area Electric Reliability Plan. Appendix D, Conservation, Load Management and Fuel Switching Analysis : Draft Environmental Impact Statement.

    Energy Technology Data Exchange (ETDEWEB)

    United States. Bonneville Power Administration.

    1991-09-01

    Various conservation, load management, and fuel switching programs were considered as ways to reduce or shift system peak load. These programs operate at the end-use level, such as residential water heat. Figure D-1a shows what electricity consumption for water heat looks like on normal and extreme peak days. Load management programs, such as water heat control, are designed to reduce electricity consumption at the time of system peak. On the coldest day in average winter, system load peaks near 8:00 a.m. In a winter with extremely cold weather, electricity consumption increases fr all hours, and the system peak shifts to later in the morning. System load shapes in the Puget Sound area are shown in Figure D-1b for a normal winter peak day (February 2, 1988) and extreme peak day (February 3, 1989). Peak savings from any program are calculated to be the reduction in loads on the entire system at the hour of system peak. Peak savings for all programs are measured at 8:00 a.m. on a normal peak day and 9:00 a.m. on an extreme peak day. On extremely cold day, some water heat load shifts to much later in the morning, with less load available for shedding at the time of system peak. Models of hourly end-use consumption were constructed to simulate the impact of conservation, land management, and fuel switching programs on electricity consumption. Javelin, a time-series simulating package for personal computers, was chosen for the hourly analysis. Both a base case and a program case were simulated. 15 figs., 7 tabs.

  4. Stochastic optimal generation bid to electricity markets with emissions risk constraints.

    Science.gov (United States)

    Heredia, F-Javier; Cifuentes-Rubiano, Julián; Corchero, Cristina

    2018-02-01

    There are many factors that influence the day-ahead market bidding strategies of a generation company (GenCo) within the framework of the current energy market. Environmental policy issues are giving rise to emission limitation that are becoming more and more important for fossil-fueled power plants, and these must be considered in their management. This work investigates the influence of the emissions reduction plan and the incorporation of the medium-term derivative commitments in the optimal generation bidding strategy for the day-ahead electricity market. Two different technologies have been considered: the high-emission technology of thermal coal units and the low-emission technology of combined cycle gas turbine units. The Iberian Electricity Market (MIBEL) and the Spanish National Emissions Reduction Plan (NERP) defines the environmental framework for dealing with the day-ahead market bidding strategies. To address emission limitations, we have extended some of the standard risk management methodologies developed for financial markets, such as Value-at-Risk (VaR) and Conditional Value-at-Risk (CVaR), thus leading to the new concept of Conditional Emission at Risk (CEaR). This study offers electricity generation utilities a mathematical model for determining the unit's optimal generation bid to the wholesale electricity market such that it maximizes the long-term profits of the utility while allowing it to abide by the Iberian Electricity Market rules as well as the environmental restrictions set by the Spanish National Emissions Reduction Plan. We analyze the economic implications for a GenCo that includes the environmental restrictions of this National Plan as well as the NERP's effects on the expected profits and the optimal generation bid. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Investigation on the electrical characteristics of a pentacene thin-film transistor and its reliability under positive drain bias stress

    International Nuclear Information System (INIS)

    Fan, Ching-Lin; Chiu, Ping-Cheng; Lin, Yu-Zuo; Yang, Tsung-Hsien; Chiang, Chin-Yuan

    2011-01-01

    This study systematically investigates the effects of pentacene deposition rates and channel lengths on the electrical characteristics of pentacene-based organic thin-film transistors (OTFTs), and the performance degradation of OTFTs under the positive drain bias stress. With a slower deposition rate of the pentacene channel layer, the larger grain size is formed, and it improves the performance of pentacene-based OTFTs. As the channel length decreases, the threshold voltage (V TH ) shifts toward the positive direction and the field-effect mobility (µ FE ) decreases, which are due to the drain-induced barrier lowering effect and the lower mobility in the active channel near the region of source/drain electrodes, respectively. In addition, we also propose a mechanism to present the channel length dependence on the field-effect mobility. Results also show that the pentacene-based OTFTs, which are under positive drain bias stress, exhibit greater performance degradation than those under negative drain bias stress. The greater performance degradation, the decreasing I ON and the larger V TH shift are due to the greater trap state density (N trap ) created in the bulk channel by the large lateral electrical field and the carriers injected into the gate insulator by the large vertical electrical field, respectively

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

    International Nuclear Information System (INIS)

    Ohlmeier, H.

    1989-01-01

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

  7. Risk programming and sparse data: how to get more reliable results

    OpenAIRE

    Hardaker, J. Brian; Lien, Gudbrand D.; Van Asseldonk, Marcel A.P.M.; Richardson, James W.; Hegrenes, Agnar

    2008-01-01

    Because relevant historical data for farms are inevitably sparse, most risk programming studies rely on few observations. We discuss how to use available information to derive an appropriate multivariate distribution function that can be sampled for a more complete representation of the possible risks in riskbased models. For the particular example of a Norwegian mixed livestock and crop farm, the solution is shown to be unstable with few states, although the cost of picking a sub-optimal pla...

  8. The design of reliability data bases, part II: competing risk and data compression

    International Nuclear Information System (INIS)

    Cooke, Roger M.

    1996-01-01

    Models for analyzing dependent competing risk data are presented. These models are designed to represent interactions of critical failure and maintenance mechanisms responsible for intercepting incipient and degraded failures, and they are fashioned such that the (constant) critical failure rate is identifiable from dependent competing risk data. Uncertainty bounds for the critical failure rate which take modeling uncertainty and statistical fluctuations into account are given

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

    Science.gov (United States)

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

    2014-05-01

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

  10. Health risks of nuclear and coal fuel cycles in electricity generation

    International Nuclear Information System (INIS)

    Kayes, R.J.; Taylor, P.J.

    1984-12-01

    A report has been prepared by the Political Ecology Research Group in which the field of comparative risk assessment of electricity generation from nuclear and coal fuel cycles is critically reviewed. Section 2 gives an introduction to risk assessments and points out the limitations of the numerical assessments that are so widely quoted. Section 3 critically reviews the major study of the UK situation, the remaining minor British studies and two American studies. Section 4 examines in detail certain areas of controversy and significance that arise in the previous section. It relates the numerical values of risk derived in Section 3 to risks in other sectors of society. Section 5 considers the significance of these estimates of risk and the conclusions are presented in section 6. (U.K.)

  11. Liberalising European electricity markets: opportunities and risks for a sustainable power sector

    International Nuclear Information System (INIS)

    Ringel, M.

    2003-01-01

    The process of liberalising European electricity markets, encompassing a wide range of restructuring activities, has mainly been spurred by the attempt to increase the economic efficiency of the whole sector. This process might be used to trigger a development towards a sustainable power sector by increasing the use of renewable energy sources and enhancing energy efficiency on the supply and demand side. However, by taking a closer look at the current trends of the European electricity markets, it becomes obvious that the liberalisation not only implies opportunities but also risks for the creation of a sustainable power sector. Many of these risks are due to market distortions and imperfections caused by the delay in creating a fully functional single European market. Thus, in the short-term, the market liberalisation tends to constitute more risks than opportunities without government actions to prevent these risks. In the long run, though, the efficiency gains of the sector and the appearance of new market factors are likely to bring forth the opportunities of liberalisation and actively foster a transformation towards a sustainable electricity sector. (author)

  12. The reliability assessment of the electromagnetic valve of high-speed electric multiple units braking system based on two-parameter exponential distribution

    Directory of Open Access Journals (Sweden)

    Jianwei Yang

    2016-06-01

    Full Text Available In order to solve the reliability assessment of braking system component of high-speed electric multiple units, this article, based on two-parameter exponential distribution, provides the maximum likelihood estimation and Bayes estimation under a type-I life test. First of all, we evaluate the failure probability value according to the classical estimation method and then obtain the maximum likelihood estimation of parameters of two-parameter exponential distribution by performing and using the modified likelihood function. On the other hand, based on Bayesian theory, this article also selects the beta and gamma distributions as the prior distribution, combines with the modified maximum likelihood function, and innovatively applies a Markov chain Monte Carlo algorithm to parameters assessment based on Bayes estimation method for two-parameter exponential distribution, so that two reliability mathematical models of the electromagnetic valve are obtained. Finally, through type-I life test, the failure rates according to maximum likelihood estimation and Bayes estimation method based on Markov chain Monte Carlo algorithm are, respectively, 2.650 × 10−5 and 3.037 × 10−5. Compared with the failure rate of a electromagnetic valve 3.005 × 10−5, it proves that the Bayes method can use a Markov chain Monte Carlo algorithm to estimate reliability for two-parameter exponential distribution and Bayes estimation is more closer to the value of electromagnetic valve. So, by fully integrating multi-source, Bayes estimation method can preferably modify and precisely estimate the parameters, which can provide a certain theoretical basis for the safety operation of high-speed electric multiple units.

  13. Did Geomagnetic Activity Challenge Electric Power Reliability During Solar Cycle 23? Evidence from the PJM Regional Transmission Organization in North America

    Science.gov (United States)

    Forbes, Kevin F.; Cyr, Chris St

    2012-01-01

    During solar cycle 22, a very intense geomagnetic storm on 13 March 1989 contributed to the collapse of the Hydro-Quebec power system in Canada. This event clearly demonstrated that geomagnetic storms have the potential to lead to blackouts. This paper addresses whether geomagnetic activity challenged power system reliability during solar cycle 23. Operations by PJM Interconnection, LLC (hereafter PJM), a regional transmission organization in North America, are examined over the period 1 April 2002 through 30 April 2004. During this time PJM coordinated the movement of wholesale electricity in all or parts of Delaware, Maryland, New Jersey, Ohio, Pennsylvania, Virginia, West Virginia, and the District of Columbia in the United States. We examine the relationship between a proxy of geomagnetically induced currents (GICs) and a metric of challenged reliability. In this study, GICs are proxied using magnetometer data from a geomagnetic observatory located just outside the PJM control area. The metric of challenged reliability is the incidence of out-of-economic-merit order dispatching due to adverse reactive power conditions. The statistical methods employed make it possible to disentangle the effects of GICs on power system operations from purely terrestrial factors. The results of the analysis indicate that geomagnetic activity can significantly increase the likelihood that the system operator will dispatch generating units based on system stability considerations rather than economic merit.

  14. Incorporating emergency evacuation planning, through human reliability analysis, in the risk management of industrial installation

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Isaac J.A. Luquetti; Carvalho, Paulo V.R.; Grecco, Claudio H.S. [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)], Email: luquetti@ien.gov.br

    2009-07-01

    An industrial installation presents many risks in the form of the process hazards, such as fire, explosion, gas and radiation release. In these situations, workers may need to evacuate from the work environment as soon as possible. In this case, the emergency evacuation planning is a key element that involves an iterative process to identify the best evacuation routes and to estimate the time required to evacuate the area at risk. The mean aspects for a successful emergency evacuation are influenced by the type of human error and the severity of the initiator event. The aim of this paper is to present a methodological framework for the identification of the performance shaping factors and prediction of human error probabilities of the responsible by the emergency evacuation of the workers in an industrial installation, providing a proactive approach for the allocation of the human factors in the risk assessment of the industrial installation. (author)

  15. Treatment of Passive Component Reliability in Risk-Informed Safety Margin Characterization FY 2010 Report

    Energy Technology Data Exchange (ETDEWEB)

    Robert W Youngblood

    2010-09-01

    The Risk-Informed Safety Margin Characterization (RISMC) pathway is a set of activities defined under the U.S. Department of Energy (DOE) Light Water Reactor Sustainability Program. The overarching objective of RISMC is to support plant life-extension decision-making by providing a state-of-knowledge characterization of safety margins in key systems, structures, and components (SSCs). A technical challenge at the core of this effort is to establish the conceptual and technical feasibility of analyzing safety margin in a risk-informed way, which, unlike conventionally defined deterministic margin analysis, is founded on probabilistic characterizations of SSC performance.

  16. Effects of Nitrogen and Hydrogen Codoping on the Electrical Performance and Reliability of InGaZnO Thin-Film Transistors.

    Science.gov (United States)

    Abliz, Ablat; Gao, Qingguo; Wan, Da; Liu, Xingqiang; Xu, Lei; Liu, Chuansheng; Jiang, Changzhong; Li, Xuefei; Chen, Huipeng; Guo, Tailiang; Li, Jinchai; Liao, Lei

    2017-03-29

    Despite intensive research on improvement in electrical performances of ZnO-based thin-film transistors (TFTs), the instability issues have limited their applications for complementary electronics. Herein, we have investigated the effect of nitrogen and hydrogen (N/H) codoping on the electrical performance and reliability of amorphous InGaZnO (α-IGZO) TFTs. The performance and bias stress stability of α-IGZO device were simultaneously improved by N/H plasma treatment with a high field-effect mobility of 45.3 cm 2 /(V s) and small shifts of threshold voltage (V th ). On the basis of X-ray photoelectron spectroscopy analysis, the improved electrical performances of α-IGZO TFT should be attributed to the appropriate amount of N/H codoping, which could not only control the V th and carrier concentration efficiently, but also passivate the defects such as oxygen vacancy due to the formation of stable Zn-N and N-H bonds. Meanwhile, low-frequency noise analysis indicates that the average trap density near the α-IGZO/SiO 2 interface is reduced by the nitrogen and hydrogen plasma treatment. This method could provide a step toward the development of α-IGZO TFTs for potential applications in next-generation high-definition optoelectronic displays.

  17. Reliability of D-Dimer test results in deciding the necessity of performing CTA in high risk population to establish the diagnosis of PE

    Directory of Open Access Journals (Sweden)

    Saher Ebrahim Taman

    2016-06-01

    Conclusion: Negative D-Dimer test is a reliable diagnostic modality to rule out the need for CT Angiography in patients at high risk population of PE. However, positive test results cannot confirm the diagnosis and further testing is warranted.

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  19. Risk evaluations of aging phenomena: the linear aging reliability model and its extensions

    International Nuclear Information System (INIS)

    Vesely, W.E.

    1987-01-01

    A model for component failure rates due to aging mechanisms has been developed from basic phenomenological considerations. In the treatment, the occurrences of deterioration are modeled as following a Poisson process. The severity of damage is allowed to have any distribution, however the damage is assumed to accumulate independently. Finally, the failure rate is modeled as being proportional to the accumulated damage. Using this treatment, the linear aging failure rate model is obtained. The applicability of the linear aging model to various mechanisms is discussed. The model can be extended to cover nonlinear and dependent aging phenomena. The implementability of the linear aging model is demonstrated by applying it to the aging data collected in NRC's Nuclear Plant Aging Research (NPAR) Program. The applications show that aging as observed in collected data have significant effects on the component failure probability and component reliability when aging is not effectively detected and controlled by testing and maintenance

  20. Risk evaluations of aging phenomena: The linear aging reliability model and its extensions

    International Nuclear Information System (INIS)

    Vesely, W.E.

    1986-01-01

    A model for component failure rates due to aging mechanisms has been developed from basic phenomenological considerations. In the treatment, the occurrences of deterioration are modeled as following a Poisson process. The severity of damage is allowed to have any distribution, however the damage is assumed to accumulate independently. Finally, the failure rate is modeled as being proportional to the accumulated damage. Using this treatment, the linear aging failure rate model is obtained. The applicability of the linear aging model to various mechanisms is discussed. The model can be extended to cover nonlinear and dependent aging phenomena. The implementability of the linear aging model is demonstrated by applying it of the aging data collected in NRC's Nuclear Plant Aging Research (NPAR) Program. The applications show that aging as observed in collected data have significant effects on the component failure probability and component reliability when aging is not effectively detected and controlled by testing and maintenance

  1. Risk programming and sparse data: how to get more reliable results

    NARCIS (Netherlands)

    Hardaker, J.B.; Lien, G.; Asseldonk, van M.A.P.M.; Richardson, W.; Hegrenes, A.

    2008-01-01

    Because relevant historical data for farms are inevitably sparse, most risk programming studies rely on few observations. We discuss how to use available information to derive an appropriate multivariate distribution function that can be sampled for a more complete representation of the possible

  2. Reliable fuzzy H∞ control for active suspension of in-wheel motor driven electric vehicles with dynamic damping

    Science.gov (United States)

    Shao, Xinxin; Naghdy, Fazel; Du, Haiping

    2017-03-01

    A fault-tolerant fuzzy H∞ control design approach for active suspension of in-wheel motor driven electric vehicles in the presence of sprung mass variation, actuator faults and control input constraints is proposed. The controller is designed based on the quarter-car active suspension model with a dynamic-damping-in-wheel-motor-driven-system, in which the suspended motor is operated as a dynamic absorber. The Takagi-Sugeno (T-S) fuzzy model is used to model this suspension with possible sprung mass variation. The parallel-distributed compensation (PDC) scheme is deployed to derive a fault-tolerant fuzzy controller for the T-S fuzzy suspension model. In order to reduce the motor wear caused by the dynamic force transmitted to the in-wheel motor, the dynamic force is taken as an additional controlled output besides the traditional optimization objectives such as sprung mass acceleration, suspension deflection and actuator saturation. The H∞ performance of the proposed controller is derived as linear matrix inequalities (LMIs) comprising three equality constraints which are solved efficiently by means of MATLAB LMI Toolbox. The proposed controller is applied to an electric vehicle suspension and its effectiveness is demonstrated through computer simulation.

  3. Author Correction: Reliability and feasibility of gait initiation centre-of-pressure excursions using a Wii® Balance Board in older adults at risk of falling.

    Science.gov (United States)

    Lee, James; Webb, Graham; Shortland, Adam P; Edwards, Rebecca; Wilce, Charlotte; Jones, Gareth D

    2018-05-12

    In the original publication, the article title was incorrectly published as 'Reliability and feasibility of gait initiation centre-of-pressure excursions using a Wii® Balance Board in older adults at risk of failing'. The correct title should read as 'Reliability and feasibility of gait initiation centre-of-pressure excursions using a Wii® Balance Board in older adults at risk of falling'.

  4. Identification of fall risk predictors in daily life measurements: gait characteristics' reliability and association with self-reported fall history.

    Science.gov (United States)

    Rispens, Sietse M; van Schooten, Kimberley S; Pijnappels, Mirjam; Daffertshofer, Andreas; Beek, Peter J; van Dieën, Jaap H

    2015-01-01

    Background. Gait characteristics extracted from trunk accelerations during daily life locomotion are complementary to questionnaire- or laboratory-based gait and balance assessments and may help to improve fall risk prediction. Objective. The aim of this study was to identify gait characteristics that are associated with self-reported fall history and that can be reliably assessed based on ambulatory data collected during a single week. Methods. We analyzed 2 weeks of trunk acceleration data (DynaPort MoveMonitor, McRoberts) collected among 113 older adults (age range, 65-97 years). During episodes of locomotion, various gait characteristics were determined, including local dynamic stability, interstride variability, and several spectral features. For each characteristic, we performed a negative binomial regression analysis with the participants' self-reported number of falls in the preceding year as outcome. Reliability of gait characteristics was assessed in terms of intraclass correlations between both measurement weeks. Results. The percentages of spectral power below 0.7 Hz along the vertical and anteroposterior axes and below 10 Hz along the mediolateral axis, as well as local dynamic stability, local dynamic stability per stride, gait smoothness, and the amplitude and slope of the dominant frequency along the vertical axis, were associated with the number of falls in the preceding year and could be reliably assessed (all P 0.75). Conclusions. Daily life gait characteristics are associated with fall history in older adults and can be reliably estimated from a week of ambulatory trunk acceleration measurements. © The Author(s) 2014.

  5. Reliability engineering

    International Nuclear Information System (INIS)

    Lee, Chi Woo; Kim, Sun Jin; Lee, Seung Woo; Jeong, Sang Yeong

    1993-08-01

    This book start what is reliability? such as origin of reliability problems, definition of reliability and reliability and use of reliability. It also deals with probability and calculation of reliability, reliability function and failure rate, probability distribution of reliability, assumption of MTBF, process of probability distribution, down time, maintainability and availability, break down maintenance and preventive maintenance design of reliability, design of reliability for prediction and statistics, reliability test, reliability data and design and management of reliability.

  6. Electricity

    International Nuclear Information System (INIS)

    Tombs, F.

    1983-01-01

    The subject is discussed, with particular reference to the electricity industry in the United Kingdom, under the headings; importance and scope of the industry's work; future fuel supplies (estimated indigenous fossil fuels reserves); outlook for UK energy supplies; problems of future generating capacity and fuel mix (energy policy; construction programme; economics and pricing; contribution of nuclear power - thermal and fast reactors; problems of conversion of oil-burning to coal-burning plant). (U.K.)

  7. A long-term risk management tool for electricity markets using swarm intelligence

    International Nuclear Information System (INIS)

    Azevedo, F.; Vale, Z.A.; Khodr, H.M.; Oliveira, P.B. Moura

    2010-01-01

    This paper addresses the optimal involvement in derivatives electricity markets of a power producer to hedge against the pool price volatility. To achieve this aim, a swarm intelligence meta-heuristic optimization technique for long-term risk management tool is proposed. This tool investigates the long-term opportunities for risk hedging available for electric power producers through the use of contracts with physical (spot and forward contracts) and financial (options contracts) settlement. The producer risk preference is formulated as a utility function (U) expressing the trade-off between the expectation and the variance of the return. Variance of return and the expectation are based on a forecasted scenario interval determined by a long-term price range forecasting model. This model also makes use of particle swarm optimization (PSO) to find the best parameters allow to achieve better forecasting results. On the other hand, the price estimation depends on load forecasting. This work also presents a regressive long-term load forecast model that make use of PSO to find the best parameters as well as in price estimation. The PSO technique performance has been evaluated by comparison with a Genetic Algorithm (GA) based approach. A case study is presented and the results are discussed taking into account the real price and load historical data from mainland Spanish electricity market demonstrating the effectiveness of the methodology handling this type of problems. Finally, conclusions are dully drawn. (author)

  8. Risks and reliability of manufacturing processes as related to composite materials for spacecraft structures

    Science.gov (United States)

    Bao, Han P.

    1995-01-01

    Fabricating primary aircraft and spacecraft structures using advanced composite materials entail both benefits and risks. The benefits come from much improved strength-to-weight ratios and stiffness-to-weight ratios, potential for less part count, ability to tailor properties, chemical and solvent resistance, and superior thermal properties. On the other hand, the risks involved include high material costs, lack of processing experience, expensive labor, poor reproducibility, high toxicity for some composites, and a variety of space induced risks. The purpose of this project is to generate a manufacturing database for a selected number of materials with potential for space applications, and to rely on this database to develop quantitative approaches to screen candidate materials and processes for space applications on the basis of their manufacturing risks including costs. So far, the following materials have been included in the database: epoxies, polycyanates, bismalemides, PMR-15, polyphenylene sulfides, polyetherimides, polyetheretherketone, and aluminum lithium. The first four materials are thermoset composites; the next three are thermoplastic composites, and the last one is is a metal. The emphasis of this database is on factors affecting manufacturing such as cost of raw material, handling aspects which include working life and shelf life of resins, process temperature, chemical/solvent resistance, moisture resistance, damage tolerance, toxicity, outgassing, thermal cycling, and void content, nature or type of process, associate tooling, and in-process quality assurance. Based on industry experience and published literature, a relative ranking was established for each of the factors affecting manufacturing as listed above. Potential applications of this database include the determination of a delta cost factor for specific structures with a given process plan and a general methodology to screen materials and processes for incorporation into the current

  9. Mobile phone radiation health risk controversy: the reliability and sufficiency of science behind the safety standards

    OpenAIRE

    Leszczynski Dariusz; Xu Zhengping

    2010-01-01

    Abstract There is ongoing discussion whether the mobile phone radiation causes any health effects. The International Commission on Non-Ionizing Radiation Protection, the International Committee on Electromagnetic Safety and the World Health Organization are assuring that there is no proven health risk and that the present safety limits protect all mobile phone users. However, based on the available scientific evidence, the situation is not as clear. The majority of the evidence comes from in ...

  10. Reliability of up-to-date risk factor between residential radon and lung cancer

    International Nuclear Information System (INIS)

    Tokonami, Shinji; Ishikawa, Tetsuo; Sorimachi, Atsuyuki; Kobayashi, Yosuke; Yoshinaga, Shinji; Quanfu, Sun; Akiba, Suminori

    2008-01-01

    Full text: The WHO launched an international radon project in January, 2005 because two major scientific articles on the residential-radon-and-lung-cancer risk have been published. Furthermore, the ICRP has just issued a new recommendation (Publ. 103). In the publication, radon issues have been mentioned using these references. They show that there is a significant correlation between radon exposures and lung cancer risks even with a somewhat lower radon concentration than an internationally recommended level (200 Bq m -3 ). In most cases, residential radon concentrations were measured by passive integrating radon monitors based on the alpha track detection techniques in their studies. We examined detection responses for the presence of thoron with some typical alpha track detectors (Kf K: Germany, Radtrak: USA and NRPB: UK), which were widely used in many epidemiological studies. In addition, we measured indoor radon and thoron concentrations in cave dwellings in Gansu Province, China, in which the National Cancer Institute (NCI) conducted a large-scale epidemiological study. The NCI concluded that there was also a significant correlation between the two aforementioned parameters, which was a similar value to recently acceptable one. However, our results on radon concentrations were obviously different from them because there was much thoron in that area. The present study demonstrates whether these risk factors are really correct throughout our data or not. Tokonami (2005) has pointed out that some of popular alpha track detectors are sensitive to thoron ( 220 Rn). This finding implies that radon readings will be overestimated and consequently may lead to biased estimates of lung cancer risk. The present study describes thoron interference on accurate radon measurements from the viewpoint of both experimental studies and field experiences. (author)

  11. 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.

  12. 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)

  13. Reliability of objects in aerospace technologies and beyond: Holistic risk management approach

    Science.gov (United States)

    Shai, Yair; Ingman, D.; Suhir, E.

    A “ high level” , deductive-reasoning-based (“ holistic” ), approach is aimed at the direct analysis of the behavior of a system as a whole, rather than with an attempt to understand the system's behavior by conducting first a “ low level” , inductive-reasoning-based, analysis of the behavior and the contributions of the system's elements. The holistic view on treatment is widely accepted in medical practice, and “ holistic health” concept upholds that all the aspects of people's needs (psychological, physical or social), should be seen as a whole, and that a disease is caused by the combined effect of physical, emotional, spiritual, social and environmental imbalances. Holistic reasoning is applied in our analysis to model the behavior of engineering products (“ species” ) subjected to various economic, marketing, and reliability “ health” factors. Vehicular products (cars, aircraft, boats, etc.), e.g., might be still robust enough, but could be out-of-date, or functionally obsolete, or their further use might be viewed as unjustifiably expensive. High-level-performance functions (HLPF) are the essential feature of the approach. HLPFs are, in effect, “ signatures” of the “ species” of interest. The HLPFs describe, in a “ holistic” , and certainly in a probabilistic, way, numerous complex multi-dependable relations among the representatives of the “ species” under consideration. ; umerous inter-related “ stresses” , both actual (“ physical” ) and nonphysical, which affect the probabilistic predictions are inherently being taken into account by the HLPFs. There is no need, and might even be counter-productive, to conduct tedious, time- and labor-consuming experimentations and to invest significant amount of time and resources to accumulate “ representative statistics” to predict - he governing probabilistic characteristics of the system behavior, such as, e.g., life expectancy of a particular type of products.

  14. Teflon/SiO2 Bilayer Passivation for Improving the Electrical Reliability of Oxide TFTs Fabricated Using a New Two-Photomask Self-Alignment Process

    Science.gov (United States)

    Fan, Ching-Lin; Shang, Ming-Chi; Li, Bo-Jyun; Lin, Yu-Zuo; Wang, Shea-Jue; Lee, Win-Der; Hung, Bohr-Ran

    2015-01-01

    This study proposes a two-photomask process for fabricating amorphous indium–gallium–zinc oxide (a-IGZO) thin-film transistors (TFTs) that exhibit a self-aligned structure. The fabricated TFTs, which lack etching-stop (ES) layers, have undamaged a-IGZO active layers that facilitate superior performance. In addition, we demonstrate a bilayer passivation method that uses a polytetrafluoroethylene (Teflon) and SiO2 combination layer for improving the electrical reliability of the fabricated TFTs. Teflon was deposited as a buffer layer through thermal evaporation. The Teflon layer exhibited favorable compatibility with the underlying IGZO channel layer and effectively protected the a-IGZO TFTs from plasma damage during SiO2 deposition, resulting in a negligible initial performance drop in the a-IGZO TFTs. Compared with passivation-free a-IGZO TFTs, passivated TFTs exhibited superior stability even after 168 h of aging under ambient air at 95% relative humidity. PMID:28788026

  15. Teflon/SiO₂ Bilayer Passivation for Improving the Electrical Reliability of Oxide TFTs Fabricated Using a New Two-Photomask Self-Alignment Process.

    Science.gov (United States)

    Fan, Ching-Lin; Shang, Ming-Chi; Li, Bo-Jyun; Lin, Yu-Zuo; Wang, Shea-Jue; Lee, Win-Der; Hung, Bohr-Ran

    2015-04-13

    This study proposes a two-photomask process for fabricating amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs) that exhibit a self-aligned structure. The fabricated TFTs, which lack etching-stop (ES) layers, have undamaged a-IGZO active layers that facilitate superior performance. In addition, we demonstrate a bilayer passivation method that uses a polytetrafluoroethylene (Teflon) and SiO₂ combination layer for improving the electrical reliability of the fabricated TFTs. Teflon was deposited as a buffer layer through thermal evaporation. The Teflon layer exhibited favorable compatibility with the underlying IGZO channel layer and effectively protected the a-IGZO TFTs from plasma damage during SiO₂ deposition, resulting in a negligible initial performance drop in the a-IGZO TFTs. Compared with passivation-free a-IGZO TFTs, passivated TFTs exhibited superior stability even after 168 h of aging under ambient air at 95% relative humidity.

  16. Teflon/SiO2 Bilayer Passivation for Improving the Electrical Reliability of Oxide TFTs Fabricated Using a New Two-Photomask Self-Alignment Process

    Directory of Open Access Journals (Sweden)

    Ching-Lin Fan

    2015-04-01

    Full Text Available This study proposes a two-photomask process for fabricating amorphous indium–gallium–zinc oxide (a-IGZO thin-film transistors (TFTs that exhibit a self-aligned structure. The fabricated TFTs, which lack etching-stop (ES layers, have undamaged a-IGZO active layers that facilitate superior performance. In addition, we demonstrate a bilayer passivation method that uses a polytetrafluoroethylene (Teflon and SiO2 combination layer for improving the electrical reliability of the fabricated TFTs. Teflon was deposited as a buffer layer through thermal evaporation. The Teflon layer exhibited favorable compatibility with the underlying IGZO channel layer and effectively protected the a-IGZO TFTs from plasma damage during SiO2 deposition, resulting in a negligible initial performance drop in the a-IGZO TFTs. Compared with passivation-free a-IGZO TFTs, passivated TFTs exhibited superior stability even after 168 h of aging under ambient air at 95% relative humidity.

  17. Effect of Heat and Electricity Storage and Reliability on Microgrid Viability: A Study of Commercial Buildings in California and New York States

    Energy Technology Data Exchange (ETDEWEB)

    Stadler, Michael; Marnay, Chris; Siddiqui, Afzal; Lai, Judy; Coffey, Brian; Aki, Hirohisa

    2009-03-10

    Berkeley Lab has for several years been developing methods for selection of optimal microgrid systems, especially for commercial building applications, and applying these methods in the Distributed Energy Resources Customer Adoption Model (DER-CAM). This project began with 3 major goals: (1) to conduct detailed analysis to find the optimal equipment combination for microgrids at a few promising commercial building hosts in the two favorable markets of California and New York, (2) to extend the analysis capability of DER-CAM to include both heat and electricity storage, and (3) to make an initial effort towards adding consideration of power quality and reliability (PQR) to the capabilities of DER-CAM. All of these objectives have been pursued via analysis of the attractiveness of a Consortium for Electric Reliability Technology Solutions (CERTS) Microgrid consisting of multiple nameplate 100 kW Tecogen Premium Power Modules (CM-100). This unit consists of an asynchronous inverter-based variable speed internal combustion engine genset with combined heat and power (CHP) and power surge capability. The essence of CERTS Microgrid technology is that smarts added to the on-board power electronics of any microgrid device enables stable and safe islanded operation without the need for complex fast supervisory controls. This approach allows plug and play development of a microgrid that can potentially provide high PQR with a minimum of specialized site-specific engineering. A notable feature of the CM-100 is its time-limited surge rating of 125 kW, and DER-CAM capability to model this feature was also a necessary model enhancement.

  18. Equilibria in the competitive retail electricity market considering uncertainty and risk management

    International Nuclear Information System (INIS)

    Kharrati, Saeed; Kazemi, Mostafa; Ehsan, Mehdi

    2016-01-01

    In a medium term planning horizon, a retailer should determine its forward contracting and pool participating strategies as well as the selling price to be offered to the customers. Considering a competitive retail electricity market, the number of clients being supplied by any retailer is a function of the selling prices and some other characteristics of all the retailers. This paper presents an equilibrium problem formulation to model the retailer's medium term decision making problem considering the strategy of other retailers. Decision making of any single retailer is formulated as a risk constraint stochastic programming problem. Uncertainty of pool prices and clients' demands is modeled with scenario generation method and CVaR (conditional value at risk) is used as the risk measure. The resulting single retailer planning problem is a quadratic constrained programming problem which is solved using the Lagrangian relaxation method and the Nash equilibrium point of the competitive retailers is achieved by successive solving of this problem for all the retailers. The performance of the proposed method is demonstrated using a realistic case study of Texas electricity market. - Highlights: • Presenting an equilibrium problem formulation for the retailer's decision-making. • Modeling consumer's retail choice behavior with an econometric model. • Managing the retailer's risk caused by rivals' strategy through CVaR. • Approximating the nonlinear price-quota curve with a piecewise-linear function. • Decomposing the nonlinear optimization problem using Lagrangian relaxation method.

  19. Phased mission analysis of maintained systems: a study in reliability risk analysis

    International Nuclear Information System (INIS)

    Terpstra, K.

    1984-01-01

    The present study develops a general theory that treats the probability of occurrence of each branch of an event tree and that takes correctly into account the dependencies between systems; incorporates within the general theory the solution of the problem of phased mission analysis. It also includes the general model components, that may or may not be repairable, with general lifetime and repairtime distribution, i.e. in the model repairable systems should be taken into account. Finally a computer program is developed that is based on this general theory, i.e. a computer program that is able to perform fully the probabilistic calculations of a risk analysis and that can handle in a correct way phased mission analysis of repairable systems. The theory is applied to a boiling water reactor accident. (Auth.)

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

    Science.gov (United States)

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

    2016-08-01

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