Impact of power uprate on environmental qualification of equipment in nuclear power plants

International Nuclear Information System (INIS)

Raheja, R.D.; Mohiuddin, A.; Alsammarae, A.

1996-01-01

Many nuclear power facilities are finding it economically beneficial to increase reactor output, from operating plants, by resorting to power uprates. A power uprate implies that a utility can increase the reactor output, or the megawatts generated, by increasing steam pressure without adding or changing any plant systems. This is perhaps one of the least expensive options for increasing the generating capacity of a power plant. However, a nuclear plant requires a comprehensive review of the plant systems, structures and components to assure their capability to withstand the resulting increased normal and accident plant conditions. A power uprate will typically result in a plant operating at higher than the originally designed environmental conditions. Safety related equipment in nuclear plants is presently qualified to the UFSAR Chapter 15 accident events and the resulting temperatures, pressures, radiation levels etc. These values will increase when the reactor is producing a higher MWe output. Components that are sensitive to the environment must be re-evaluated and assessed to determine their acceptability and operability under the revised environmental conditions. Most safety-related mechanical and electrical equipment will require an assessment from an environmental qualification standpoint. Utilities must perform this task in a systematic, auditable and cost effective manner to optimize their resources and minimize plant costs associated with modifications, replacements or equipment testing. This paper discusses various approaches and provides recommendations to achieve equipment qualification while satisfying the plant's objective of a power uprate

77 FR 4585 - Advisory Committee on Reactor Safeguards (ACRS) Meeting of the ACRS Subcommittee on Power Uprates...

Science.gov (United States)

2012-01-30

... Subcommittee on Power Uprates; Notice of Meeting The ACRS Subcommittee on Power Uprates will hold a meeting on... Turkey Point, Units 3 and 4, extended power uprate application. The Subcommittee will hear presentations... possible, so that appropriate arrangements can be made. Thirty-five hard copies of each presentation or...

77 FR 28637 - Advisory Committee On Reactor Safeguards (ACRS) Meeting of the ACRS Subcommittee on Power Uprates...

Science.gov (United States)

2012-05-15

... Subcommittee on Power Uprates; Notice of Meeting The ACRS Subcommittee on Power Uprates will hold a meeting on...) associated with the Grand Gulf Nuclear Station Unit 1 extended power uprate application. The Subcommittee... made. Thirty-five hard copies of each presentation or handout should be provided to the DFO thirty...

Key considerations and safety issues for the stretch power uprate at Chinshan Nuclear Power Station

Energy Technology Data Exchange (ETDEWEB)

Huang, P., E-mail: u808966@taipower.com.tw [Taiwan Power Company, Taipei, Taiwan (China)

2014-07-01

The Taiwan Power Company (TPC) has elected in recent years to implement the power uprate program as a key measure to improve the performance for TPC's nuclear power plants. The Measurement Uncertainty Recapture (MUR) power uprate for the TPC's three operating plants (reported in 16th PBNC) had been successfully implemented by July 2009. For the stretch power uprate (SPU) followed, the magnitude of uprate (~3%) is determined based on the available margins for original plant design, constant pressure approach (BWR) is adopted to simplify the evaluation, and major plant modifications are not considered. As the first application, the SPU safety analysis report (SAR) for the Chinshan plant was submitted to the ROCAEC in December 2010. A review task force was organized by the ROCAEC to perform a very thorough review. As the licensing bases are fully re-examined during the review process, many important issues have been identified and addressed. The key issues resolved include: conformance of SAR to ROCAEC's review guidance; re-examination of post-Fukushima comprehensive safety assessment; qualification of containment protective coatings; GL 96-06 (Assurance of Equipment Operability and Containment Integrity During DBA Conditions); credit for Containment Accident Pressure; issue for Annulus Pressurization Loads Evaluation. These issues required very extensive efforts to resolve. With the cooperative efforts by TPC and contractor (Institute of Nuclear Energy Research), however, all the issues were fully clarified and SAR was approved by ROCAEC on November 15, 2012. The first step SPU (2% OLTP) was successfully implemented in November 2012 at both units. (author)

Nuclear power plant outages

International Nuclear Information System (INIS)

1998-01-01

The Finnish Radiation and Nuclear Safety Authority (STUK) controls nuclear power plant safety in Finland. In addition to controlling the design, construction and operation of nuclear power plants, STUK also controls refuelling and repair outages at the plants. According to section 9 of the Nuclear Energy Act (990/87), it shall be the licence-holder's obligation to ensure the safety of the use of nuclear energy. Requirements applicable to the licence-holder as regards the assurance of outage safety are presented in this guide. STUK's regulatory control activities pertaining to outages are also described

Nuclear power plant outage optimisation strategy

International Nuclear Information System (INIS)

2002-10-01

Competitive environment for electricity generation has significant implications for nuclear power plant operations, including among others the need of efficient use of resources, effective management of plant activities such as on-line maintenance and outages. Nuclear power plant outage management is a key factor for good, safe and economic nuclear power plant performance which involves many aspects: plant policy, co-ordination of available resources, nuclear safety, regulatory and technical requirements and, all activities and work hazards, before and during the outage. This technical publication aims to communicate these practices in a way they can be used by operators and utilities in the Member States of the IAEA. It intends to give guidance to outage managers, operating staff and to the local industry on planning aspects, as well as examples and strategies experienced from current plants in operation on the optimization of outage period. This report discusses the plant outage strategy and how this strategy is actually implemented. The main areas identified as most important for outage optimization by the utilities and government organizations participating in this report are: organization and management; outage planning and preparation, outage execution, safety outage review, and counter measures to avoid extension of outages and to easier the work in forced outages. This report was based on discussions and findings by the authors of the annexes and the participants of an Advisory Group Meeting on Determinant Causes for Reducing Outage Duration held in June 1999 in Vienna. The report presents the consensus of these experts regarding best common or individual good practices that can be used at nuclear power plants with the aim to optimize

75 FR 7634 - Advisory Committee on Reactor Safeguards (ACRS); Meeting of the Subcommittee on Power Uprates...

Science.gov (United States)

2010-02-22

... NUCLEAR REGULATORY COMMISSION Advisory Committee on Reactor Safeguards (ACRS); Meeting of the Subcommittee on Power Uprates; Notice of Meeting The ACRS Subcommittee on Power Uprates will hold a meeting on... arrangements can be made. Thirty-five hard copies of each presentation or handout should be provided to the DFO...

76 FR 32240 - Advisory Committee on Reactor Safeguards (ACRS) Meeting on the ACRS Subcommittee on Power Uprates

Science.gov (United States)

2011-06-03

... Subcommittee on Power Uprates Notice of Meeting The ACRS Subcommittee on Power Uprates will hold a meeting on... Expanded Operating Domains-Power Distribution Validation and Pin-by-Pin Gamma Scan). The Subcommittee will... hard copies of each presentation or handout should be provided to the DFO thirty minutes before the...

78 FR 70596 - Advisory Committee on Reactor Safeguards (ACRS) Meeting of the ACRS Subcommittee on Power Uprates...

Science.gov (United States)

2013-11-26

... Subcommittee on Power Uprates; Notice of Meeting The ACRS Subcommittee on Power Uprates will hold a meeting on... hold discussions with the licensee, (Northern States Power Company of Minnesota), the NRC staff, and... made. Thirty-five hard copies of each presentation or handout should be provided to the DFO thirty...

Nuclear plant power up-rate study: feedwater heater evaluations

International Nuclear Information System (INIS)

Svensson, Eric; Catapano, Michael; Coakley, Michael; Thomas, Dan

2014-01-01

Given today's nuclear industry business climate, it has become common for Utility companies to consider increasing unit capacities through turbine replacement and power up-rates. An integral part of the studies conducted by many towards this end, involve the generation of a set of turbine cycle heat balances with predicted performance parameters for the up-rated condition. Once these tentative operating values are established, it becomes necessary to evaluate the suitability of the existing components within each system to ensure they are capable of continued safe and reliable operation. The ultimate cost for the up-rate, including the cost for any major required modifications or significant replacements is weighed against increased revenue generated from the up-rate over time. Exelon's Peach Bottom Atomic Power Station (PBAPS) is currently planning for an Extended Power up-rate (EPU) for both units. To ensure the existing Feedwater Heaters (FWH) could maintain the operating and transient response margins at the EPU condition, an engineering study was conducted. Powerfect Inc. in conjunction with SPX Heat Transfer LLC were contracted to provide engineering services to analyze the design, thermal performance, reliability and operating conditions at projected EPU conditions. Specifically, to address the following with regard to the station's Feedwater Heaters (FWHs): 1. Evaluate Drain Cooler (DC) Velocities - including zone inlet velocity, cross and window velocities and outlet velocities. 2. Evaluate Drain Cooler Zone Pressure Drop for effect on drain cooler margins to flashing. 3. Evaluate differential pressure allowable across the pass partition plate. 4. Evaluate Drain Cooler Tube Vibration Potential. 5. Perform detailed steam dome velocity calculations. The goal of the study was to identify the most susceptible areas within the heaters for problems and potential failures when operating at the higher duty of the EPU condition for the remaining life

Audit Calculations of ATWS for Ulchin Unit 1 and 2 Power Uprate

Energy Technology Data Exchange (ETDEWEB)

Lee, Jun Soo; Huh, Byung Gil; Choi, Yong Seog; Seul, Kwang Won [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

2013-10-15

In this study, the regulatory audit calculation for ATWS of Ulchin Unit 1 and 2 with 4.5% power uprate was performed to support the licensing review and to confirm the validity of licensee's calculation. In order to simulate the transient behavior of ATWS initiated by a loss of feed water, the systems of Ulchin Unit 1 and 2 was modeled with MARS-KS 1.3. In this study, the regulatory audit calculation of ATWS for Ulchin 1 and 2 with 4.5% power uprating and 99% MTC in the specific cycle designs was performed. It is conformed that the analysis results of ATWS for Ulchin 1 and 2 power uprate meets the RCS pressure acceptance criteria. An anticipated transient accompanied by a failure in the Reactor Trip System (RTS) to shut down the reactor is defined as an Anticipated Transient Without Scram (ATWS). Under certain postulated conditions, the ATWS could lead to Reactor Coolant system (RCS) pressure boundary fracture and/or core damage. For a conventional pressurized water reactor (PWR), the temperature corresponding to the NSSC notice No.2013.09(Performance Criteria for ECCS of the Pressurized Water Reactor Nuclear Power Plants), 1204 .deg. C and the pressure corresponding to the ASME Boiler and Pressure Vessel Code service level C stress, 221.5 bar is assumed to be an unacceptable plant condition against ATWS, above which the RCS pressure boundary could deform to the point of inoperability and the safe shutdown by injection of borated water could be challenged. Such potentially excessive RCS overpressure may occur in the ATWS initiated from a loss of heat sink. Currently, the modification of Ulchin 1 and 2 operating license for 4.5% power uprate is under review.

Up-Rating - An Alternative Approach to Meeting Future Power Demands - Exploitation of Design Margins

Energy Technology Data Exchange (ETDEWEB)

Bruce, Barnaby; Schwarz, Thomas [AREVA NP GmbH, Freyeslebenstr. 1, 91058 Erlangen (Germany)

2008-07-01

Up-rating is a world-wide implemented approach that takes advantage of increased calculation and analytic abilities developed since commissioning and applies them to old plants. In doing so, what would possibly be considered today as over-engineered design margins are exploited and plant performance is improved, without necessarily involving extensive modifications or replacement of hardware. It is therefore a short-term alternative, compared to new plants, with little change in environmental ramifications for power production capacity gained. Up-rating is also more accepted by the wider community and licensing authorities, thus complimenting the building of new plants. The 10% thermal up-rating of the nuclear power plant at Almaraz, Spain, requires a comprehensive reanalysis of all power components. This paper focuses on those measures required to ensure the performance of the steam generators at increased load as an example of design margin exploitation in such crucial components. (authors)

Nuclear Power Plant Outage Optimization Strategy. 2016 Edition

International Nuclear Information System (INIS)

2016-10-01

This publication is an update of IAEA-TECDOC-1315, Nuclear Power Plant Outage Optimisation Strategy, which was published in 2002, and aims to communicate good outage management practices in a manner that can be used by operators and utilities in Member States. Nuclear power plant outage management is a key factor for safe and economic nuclear power plant performance. This publication discusses plant outage strategy and how this strategy is actually implemented. The main areas that are important for outage optimization that were identified by the utilities and government organizations participating in this report are: 1) organization and management; 2) outage planning and preparation; 3) outage execution; 4) safety outage review; and 5) counter measures to avoid the extension of outages and to facilitate the work in forced outages. Good outage management practices cover many different areas of work and this publication aims to communicate these good practices in a way that they can be used effectively by operators and utilities

From initial application to routine operation: Reviewing the Applications for Power Uprates

International Nuclear Information System (INIS)

Garis, Ninos; Skaanberg, Lars

2007-01-01

Current plans for power uprates in Swedish nuclear power plants will lead to significant increases in seven units and a lesser increase in one unit. To date SKI has received six applications, and two more are due in 2007. A power uprate process is initiated by the application to the Government by a licensee for approval to increase the thermal output of a reactor unit. This request is addressed to the Government and is forwarded to SKI for a preliminary safety review. The result of the review is then provided by SKI as a basis for a governmental decision. Six applications have been taken through the first stage of the process; of these, three have received governmental approval and three are currently awaiting a decision. If the licensee's application is approved by the Government, deeper analyses and studies are required in order to modify the plant and update the safety analysis report and the associated technical specifications. SKI reviews this material on a continuous basis prior to test and routine operation at the increased power level. There are four stages that require attention and review by SKI; 1. Review of the application to the Government for approval to operate at increased power levels, and preparation of a suitable answer. 2. Review and approval of the preliminary safety analysis report (PSAR) 3. Review and approval of the application for testing at the higher power level 4. Review and approval of routine operation at the higher power level. A thorough description of the handling of a power uprate process can be found in the SKI PM (SKI-PM 04:11) that is available on the SKI website (in Swedish)

The status of the Hanaro class 4 power outage

International Nuclear Information System (INIS)

Hyungkyoo, K.; Hoansung, J.; Jongsup, W.

2004-01-01

Electric power is essential for all industrial plant. All who use electric power desire a perfect frequency, voltage stability, and reliability all the time. But this cannot be realized in practice because of the many causes of a power supply disturbance that are beyond the control of the utility. Since the first criticality of the Hanaro research reactor, the major reasons for reactor trips were system malfunctions and inexperienced operators in the initial stage of its operation. As Hanaro is stabilizing, the power supply outage becomes the major reason for a reactor trip. This paper describes the status of power supply outages. This paper deals with not only the outages which have an effect on Hanaro operation but also the reasons for the Hanaro class-4 power outages. The class-4 power is a commercial power which supplies the load centers and the large motors such as primary cooling pumps and secondary cooling pumps. Even if a class-4 power outage occurs, Hanaro is safe because of the reactor cooling by natural convection and the flywheel effect of the primary cooling pumps. The analysis of the characteristics and the trends of the outages can provide clues to how the outages can be minimized and what the impact of the outages are on the operation. For the site-wide class-4 power, the latest failure rate has been 2.36 per year and the mean time to repair is 23,78 minutes for the exponentially weighted mowing average. The unavailability of the Class-4 power is 1.5 10 -4

Pricing power outages in the Netherlands

Energy Technology Data Exchange (ETDEWEB)

Baarsma, Barbara E.; Hop, J. Peter [SEO Economic Research/University of Amsterdam, Amsterdam (Netherlands)

2009-09-15

In most Western countries, the power grid provides electricity more than 99% of the time. To maintain reliability at such high levels, energy companies have to continually invest in electric transmission- and distribution systems. Since customers of electricity cannot switch from one distribution network to another, no economic incentive exists that matches the supplied reliability to customer preferences. Either under- or over-investment in reliability may thus result. In order to introduce market-like incentives, the Dutch Energy Regulator introduced a regulatory system based on the (perceived) costs of power outages. An essential ingredient of the regulation is the cost of a power outage of a particular duration (i.e., 1 minute). This paper measures these outage cost by using conjoint analysis. We find that the social cost of the present Dutch level of reliability - that is, one outage of two hours every four years - is EUR2.80 on average for every household, and EUR33.10 on average for every SME firm. The total costs to Dutch society are almost EUR50 million. (author)

Characteristic evaluations of BWR uprate method based on heat balance shift concept

International Nuclear Information System (INIS)

Kitou, Kazuaki; Aoyama, Motoo; Shiina, Kouji; Sasaki, Hiroshi; Yoshikawa, Kazuhiro

2007-01-01

Reactor power uprate of nuclear power plants is an efficient plant operating method. Most BWR plants need the exchange of high pressure turbines when plant thermal power increases over 5% because main steam flow rate exceeds the limitation of inlet steam flow rate of a high pressure turbine. Therefore, the new power uprate method named heat balance shift power uprate method has been developed. This method decreases feedwater temperature with increasing plant thermal power not to increase main steam flower rate. This study clarified that the heat balance shift method could increase plant electric power up to 2.8% compared with conventional power uprate method without the exchange of a high pressure turbine. (author)

Management strategies for nuclear power plant outages

International Nuclear Information System (INIS)

2006-01-01

More competitive energy markets have significant implications for nuclear power plant operations, including, among others, the need for more efficient use of resources and effective management of plant activities such as on-line maintenance and outages. Outage management is a key factor for safe, reliable and economic plant performance and involves many aspects: plant policy, coordination of available resources, nuclear safety, regulatory and technical requirements, and all activities and work hazards, before and during the outage. The IAEA has produced this report on nuclear power plant outage management strategies to provide both a summary and an update of a follow-up to a series of technical documents related to practices regarding outage management and cost effective maintenance. The aim of this publication is to identify good practices in outage management: outage planning and preparation, outage execution and post-outage review. As in in the related technical documents, this report aims to communicate these practices in such a way that they can be used by operating organizations and regulatory bodies in Member States. The report was prepared as part of an IAEA project on continuous process improvement. The objective of this project is to increase Member State capabilities in improving plant performance and competitiveness through the utilization of proven engineering and management practices developed and transferred by the IAEA

Predicting Power Outages Using Multi-Model Ensemble Forecasts

Science.gov (United States)

Cerrai, D.; Anagnostou, E. N.; Yang, J.; Astitha, M.

2017-12-01

Power outages affect every year millions of people in the United States, affecting the economy and conditioning the everyday life. An Outage Prediction Model (OPM) has been developed at the University of Connecticut for helping utilities to quickly restore outages and to limit their adverse consequences on the population. The OPM, operational since 2015, combines several non-parametric machine learning (ML) models that use historical weather storm simulations and high-resolution weather forecasts, satellite remote sensing data, and infrastructure and land cover data to predict the number and spatial distribution of power outages. A new methodology, developed for improving the outage model performances by combining weather- and soil-related variables using three different weather models (WRF 3.7, WRF 3.8 and RAMS/ICLAMS), will be presented in this study. First, we will present a performance evaluation of each model variable, by comparing historical weather analyses with station data or reanalysis over the entire storm data set. Hence, each variable of the new outage model version is extracted from the best performing weather model for that variable, and sensitivity tests are performed for investigating the most efficient variable combination for outage prediction purposes. Despite that the final variables combination is extracted from different weather models, this ensemble based on multi-weather forcing and multi-statistical model power outage prediction outperforms the currently operational OPM version that is based on a single weather forcing variable (WRF 3.7), because each model component is the closest to the actual atmospheric state.

Implications of power uprates on safety margins of nuclear power plants. Report of a technical meeting

International Nuclear Information System (INIS)

2004-09-01

The safety of nuclear power plants (NPPs) is based on the defence in depth concept, which relies on successive physical barriers (fuel matrix, cladding, primary system pressure boundary and containment) and other provisions to control radioactive materials and on multiple levels of protection against damage to these barriers. Deterministic safety analysis is an important tool for conforming the adequacy and efficiency of provisions within the defence in depth concept and is used to predict the response of an NPP in predetermined operational states. This type of safety analysis applies a specific set of rules and specific acceptance criteria. Deterministic analysis is typically focused on neutronic, thermohydraulic, radiological and structural aspects, which are often analysed with different computational tools. The advanced computational tools developed for deterministic safety analysis are used for better establishment and utilization of licensing margins or safety margins in consideration of analysis results. At the same time, the existence of such margins ensures that NPPs operate safely in all modes of operation and at all times. To properly assess and address the existing margins and to be able to take advantage of unnecessary conservatisms, state of the art analytical tools intended for safety assessment have been developed. Progress made in the development and application of modern codes for safety analysis and better understanding of phenomena involved in plant design and operation enable the analysts to determine safety margins in consideration of analysis results (licensing margins) with higher precision. There is a general tendency for utilities to take advantage of unnecessarily large conservatisms in safety analyses and to utilize them for reactor power uprates, better utilization of nuclear fuel, higher operational flexibility and for justification of lifetime extension. The present publication sets forth the results of a Technical Meeting on the

Indicators for management of planned outages in nuclear power plants

International Nuclear Information System (INIS)

2006-04-01

The outages considered within the scope of this publication are planned refuelling outages (PWR and BWR nuclear power plants) and planned outages associated with major maintenance, tests and inspections (PHWR and LWGR nuclear power plants). The IAEA has published some valuable reports providing guidance and assistance to operating organizations on outage management. This TECDOC outlines main issues to be considered in outage performance monitoring and provides guidance to operating organizations for the development and implementation of outage programmes which could enhance plant safety, reliability and economics. It also complements the series of reports published by the IAEA on outage management and on previous work related to performance indicators developed for monitoring different areas of plant operation, such as safety, production, reliability and economics. This publication is based upon the information presented at a technical meeting to develop a standardized set of outage indicators for outage optimization, which was organised in Vienna, 6-9 October 2003. At this meeting, case studies and good practices relating to performance indicator utilization in the process of planned outage management were presented and discussed

Measurement uncertainty recapture (MUR) power uprates operation at Kuosheng Nuclear Power Station

International Nuclear Information System (INIS)

Chang Chinjang; Wang Tunglu; Lin Chihpao

2009-01-01

Measurement Uncertainty Recapture PowerUprates (MUR PU) are achieved through the use of state-of-the-art feedwater flow measurement devices, i.e., ultrasonic flow meters (UFMs), that reduce the degree of uncertainty associated with feedwater flow measurement and in turn provide for a more accurate calculation of thermal power. The Institute of Nuclear Energy Research (INER) teamed with Sargent and Lundy, LLC (S and L), Pacific Engineers and Constructors, Ltd (PECL), and AREVA to develop a program and plan for the Kuosheng Nuclear Power Station (KNPS) MUR PU Engineering Service Project and for the assistance to Kuosheng MUR PU operation. After regulator's approval of the licensing requests, KSNPS conducted the power ascension test and switchover to the new rated thermal power for Unit 2 and Unit 1 on 7/7/2007 and 11/30/2007, respectively. From then on, KNPS became the first nuclear power plant implementing MUR PU operation in Taiwan and in Asia. (author)

Estimating Power Outage Cost based on a Survey for Industrial Customers

Science.gov (United States)

Yoshida, Yoshikuni; Matsuhashi, Ryuji

A survey was conducted on power outage cost for industrial customers. 5139 factories, which are designated energy management factories in Japan, answered their power consumption and the loss of production value due to the power outage in an hour in summer weekday. The median of unit cost of power outage of whole sectors is estimated as 672 yen/kWh. The sector of services for amusement and hobbies and the sector of manufacture of information and communication electronics equipment relatively have higher unit cost of power outage. Direct damage cost from power outage in whole sectors reaches 77 billion yen. Then utilizing input-output analysis, we estimated indirect damage cost that is caused by the repercussion of production halt. Indirect damage cost in whole sectors reaches 91 billion yen. The sector of wholesale and retail trade has the largest direct damage cost. The sector of manufacture of transportation equipment has the largest indirect damage cost.

Good practices for outage management in nuclear power plants

International Nuclear Information System (INIS)

1991-09-01

As a follow-up to an earlier Technical Document on Good Practices for Improved Nuclear Power Plant Performance (IAEA-TECDOC-498), the Agency has produced a more focused technical report on good practices associated with nuclear power plant outage planning and execution. As with the earlier document, the overall aim is that by identifying good practices in the key aspects of outage management, overall world nuclear performance will improve and the gap between excellent performers and operators with developing programmes will be narrowed. This document has been produced through the contribution of numerous operators and government agencies. It aims at minimizing text and focusing on actual good practices in use which can be found in the annexes. While the specific methods used to achieve excellence in maintenance/refuelling outages may differ, the fundamental requirements of outage management are discussed

Planning and management of outages in nuclear power plants

International Nuclear Information System (INIS)

Sica, G.F.; Fusari, W.; Reginelli, A.

1984-01-01

At present the Ente Nazionale per l'Energia Elettrica (ENEL) operates three nuclear power plants, only one of which belongs to the new generation, i.e. the Caorso Nuclear Power Plant which has been in commercial operation since December 1981. Outage planning, implementation and analysis are very important in order to minimize the shutdown time and thus improve plant availability, which is of particular importance for a large nuclear power plant. Such activities are very complicated because of the large number of jobs that have to be performed in accordance with detailed written procedures and which have to be properly documented and controlled. Large off-site resources are required which have to be accurately interfaced with on-site staff. The ENEL is making a great effort to define both the administrative and technical aspects of refuelling outages. As outage planning requires the availability and handling of a large amount of data and information, a maintenance information system that has been widely used in conventional plants was applied, with some modifications made especially for the Caorso Nuclear Power Plant. After two years the following results have been achieved: a large number of raw and processed data are now available, the first refuelling outage was carried out with few problems and according to schedule, and the second refuelling outage, based on the experience of the first, required somewhat less preparation and is developing well even though many special activities have had to be scheduled. The ENEL believes that the efforts made in the planning and management areas will pay off in terms of the short duration, smoothness and economy of further outages, both for Caorso and for future plants. (author)

Primary Water Chemistry Control during a Planned Outage at Bruce Power

International Nuclear Information System (INIS)

Ma, Guoping; Nashiem, Rod; Matheson, Shane; Yabar, Berman; Harper, Bill; Roberts, John G.

2012-09-01

Bruce Power has developed a comprehensive outage water chemistry program, which includes both primary and secondary chemistry requirements during planned outages. The purpose of the program is to emphasize the chemistry requirements during outages and subsequent start-ups in order to maintain the integrity of the systems, minimise activity transport and radiation fields, reduce the Carbon-14 release, and to ensure that the requirements are integrated with the outage management program. Prior to a planned outage, Station Chemical Technical Sections identify outage chemistry requirements to Operations and Outage Planning and ensure that work necessary to correct system chemistry issues is within outage work scope. The outage water chemistry program provides direction for establishing alternative sampling locations as demanded by the system configuration during the outage and identifies outage prerequisites for nuclear system purification capabilities. These requirements are contained in an outage checklist. The paper mainly highlights the primary water chemistry issues and chemistry control strategies during planned outages and discusses challenges and successes. (authors)

Questions and perceptions about nuclear power plant outages

International Nuclear Information System (INIS)

Mc Donald, R.P.

1985-01-01

The most commonly used measure of nuclear power plant productivity is ''availability'' which is usually construed to be the percentage of time in a given period that a nuclear unit is actually tied to a grid supplying electrical power. When a unit is not tied to a grid, it is in an ''outage'' condition, possibly being shutdown, refueled, repaired, or in some stage of startup. There are some very positive by-products of well performed outages in addition to cost and availability enhancements: almost all supervisory and engineering personnel participate in planning and preparations. This approach promotes the professional and leadership development of each person, the supervisors and engineers participate in a competitive venture as a team and enjoy and benefit from comparative interactions with other utilities, perhaps the greatest benefit reaped from the development of outage management expertise is the improved ability to handle unexpected plant problems

Options for shortening nuclear power plant refueling outages

International Nuclear Information System (INIS)

Kastl, H.

2001-01-01

Deregulation of the European electricity market on 01.01.1999 forced a large number of electric utilities- especially nuclear power plant operators - to find ways of drastically cutting down their costs in order to be able to compete successfully within the new market environment. Nuclear power plants currently in operation mainly have three potential ways of reducing their power generating costs: by increasing plant availability, reducing fuel costs and cutting down operating costs. The optimization of plant refueling outages offers considerable potential for enhancing plant availability, but also helps bring down operating costs by reducing expenditure on maintenance. In order to optimize an outage in terms of its duration and costs, a variety of approaches are possible - all of which, however, involve certain key factors such as good organization, planning, logistics and control, improvement of equipment and tools, as well as motivation of personnel. Another aspect is the introduction of innovative technologies. In the last few years, such technologies have frequently enabled maintenance effort to be reduced, thus saving considerable time, and have also resulted in a need for fewer personnel to carry out the work, thus reducing radiation exposure. In many instances they have also improved the quality of work and outage performance as a whole. The paper uses recent examples to show how innovative technologies can contribute to-wards reducing nuclear plant maintenance costs and shorten the duration of refueling out-ages. (author)

Estimating the spatial distribution of power outages during hurricanes in the Gulf coast region

International Nuclear Information System (INIS)

Han, S.-R.; Guikema, Seth D.; Quiring, Steven M.; Lee, Kyung-Ho; Rosowsky, David; Davidson, Rachel A.

2009-01-01

Hurricanes have caused severe damage to the electric power system throughout the Gulf coast region of the US, and electric power is critical to post-hurricane disaster response as well as to long-term recovery for impacted areas. Managing power outage risk and preparing for post-storm recovery efforts requires accurate methods for estimating the number and location of power outages. This paper builds on past work on statistical power outage estimation models to develop, test, and demonstrate a statistical power outage risk estimation model for the Gulf Coast region of the US. Previous work used binary hurricane-indicator variables representing particular hurricanes in order to achieve a good fit to the past data. To use these models for predicting power outages during future hurricanes, one must implicitly assume that an approaching hurricane is similar to the average of the past hurricanes. The model developed in this paper replaces these indicator variables with physically measurable variables, enabling future predictions to be based on only well-understood characteristics of hurricanes. The models were developed using data about power outages during nine hurricanes in three states served by a large, investor-owned utility company in the Gulf Coast region

Verification and Enhancement of VIIRS Day-Night Band Power Outage Detection Product

Science.gov (United States)

Burke, A.; Schultz, L. A.; Omitaomu, O.; Molthan, A.; Cole, T.; Griffin, R.

2017-12-01

The NASA SPoRT (Short-term Prediction Research and Transition) Center has collaborated with scientists at NASA Goddard Space Flight Center to create a power outage detection product from radiance data obtained by the VIIRS (Visible Infrared Imaging Radiometer Suite) sensor aboard the Suomi-NPP satellite. This product uses a composite of pre-event radiance values from the VIIRS Day-Night Band to establish a baseline of "normal" nighttime lights for a study area. Then, after a severe weather event or other disaster, post-event images are compared to the composite to generate a percent-of-normal radiance product to identify areas that are experiencing outages and to aid in disaster response and monitor recovery. This project will use ground-truth county-level outage data provided by Oak Ridge National Laboratory (ORNL) in order validate the product and to establish a percent-of-normal threshold for identifying power outages. Once a threshold is found, ORNL's LandScan Global population data will be combined with the product to estimate how many electrical customers are being affected by power outages after a disaster. Two case studies will be explored to examine power outage recovery after severe weather events, including Hurricane Matthew from 2016 and the Washington D.C. Derecho event of 2012.

Water chemistry experience following an extensive power up-rate in Oskarshamn 3 BWR

International Nuclear Information System (INIS)

Wegemar, Boerje; Nilsson, Jimmy; Lejon Johan; Bergfors, Asa; Arnberg, Bo

2012-09-01

The Swedish Oskarshamn 3 BWR plant, operated by OKG, was first connected to the grid in 1985. The plant has been power up-rated in two steps; from the original design, 3020 MWth, to 3300 MWth (109%, 1989) and recently to 3900 MWth (129%, 2009). Westinghouse Electric Sweden AB (former ASEA-Atom, OEM of the plant) was rewarded a major contract in the recently implemented up-rating project, the PULS project. The PULS project is quite unique since no operating experience has to date been reported from a similar major power up-rate in a BWR plant. Water chemistry experience from the first period of operation following the implementation of the PULS project is reported and discussed in the paper. Reported chemistry and radiochemistry measurements in feedwater (FW) and reactor water (RW) include corrosion products, activated corrosion products, dissolved oxygen and impurities like chloride, sulfate etc. Furthermore, a comparison of water quality prior to implementation of the PULS project is included. Several process systems have been modified, one of them being the condensate cleanup system (CCU), a Pre-coat filter system. The design criteria for the CCU system include the filter run-lengths, pressure drop before back-washing and requirements on water chemistry quality. The paper describes in some detail the CCU system modifications being implemented in order to fulfil the design criterion. CCU cleanup efficiency, operating temperature and influence of hydrogen peroxide on the CCU resin are all important issues being covered in the paper. As for the latter, it is well known that oxygen and hydrogen peroxide (from radiolysis in the core region) might cause partial deterioration of CCU standard cation resin resulting in increased RW sulfate concentrations. This aspect is covered in the paper as well. The reactor water cleanup system (RWCU) in Oskarshamn 3 consists of deep bed ion exchange filters (mixed bed filter). The purpose of RWCU is to maintain a low level of

Fuel and Core Design Verification for Extended Power Up-rate in Ringhals Unit 3

International Nuclear Information System (INIS)

Gabrielsson, Petter; Stepniewski, Marek; Almberger, Jan

2006-01-01

Vattenfall's Westinghouse 3-loop PWR Ringhals 3 at the western coast of Sweden is scheduled for an extended power up-rate from 2783 to 3160 MWt in 2007, in the frame of the so called GREAT-project. The project will realize an up-rating initially planned and analysed back in 1995, but with a number of significant improvements outlined in this paper. For the licensing of the up-rated power level, a complete revision of the safety analyses, radiological analyses and systems verifications in FSAR is being performed by Westinghouse Electrics Belgium. The work is performed in close cooperation with Vattenfall in the areas of core calculations and input data. For more than a decade, Vattenfall has performed all core design and reload safety evaluations (RSE) for Ringhals, independent of fuel vendors and safety analysts. In GREAT all core parameters in the safety analysis checklist (SAC) used for the safety analyses are determined based upon a set of nine reference loading patterns designed by Vattenfall covering a wide range of fuel and core designs and extreme cycle-to-cycle variations. To facilitate the calculation of SAC parameters Westinghouse has provided a Reload Safety Evaluation Procedure report (RSEP) with detailed specifications for the calculation of all core parameters used in the analyses. The procedure has been automatized by Vattenfall in a set of scripts executing 3D core simulator calculations and extracting the key results. The same tools will be used in Vattenfall's future RSE for Ringhals 3. This approach is taken to obtain consistency between core designs and core calculations for the safety analyses and the cycle specific calculations, to minimize the risk for future violations of the safety analyses. (authors)

Evaluation of Steam Generator Level behavior for Determination of Turbine Runback rate on COPs trip for Yonggwang 1 and 2 Power Uprating Units

International Nuclear Information System (INIS)

Lee, Kyung Jin; Hwang, Su Hyun; Yoo, Tae Geun; Chung, Soon Il; An, Byung Chang; Park, Jung Gu

2010-01-01

4.5% power uprate project has been progressing for the first time in Yonggwang 1 and 2(YGN1 and 2). Reviews for design change due to the power uprate were accomplished. Steam generator level behavior was one of the most important parameters because it could be cause of reactor trip or turbine trip. As the results of the reviews, YGN1 and 2 had to reassess it for change of turbine runback rate when turbine runback occurs due to the condensate operating pumps (COP) trip. This study has been carried out for evaluating the steam generator level behavior for determination of turbine runback rate on COPs trip for Yonggwang 1 and 2 Power Uprating Units. The steam generator water level evaluation program for YGN1 and 2 (SLEP-Y1) has been developed for it. The program includes models for the steam generator water level response. SLEP-Y1 is programmed with advanced continuous system simulation language (ACSL). The language has been used to simulate physical systems as a commercial tool used to evaluate system designs

Ontario-U.S. power outages : impacts on critical infrastructure

International Nuclear Information System (INIS)

2006-01-01

This paper described the power outage and resulting blackout that occurred on August 14, 2003 and identified how critical infrastructure was directly and interdependently impacted in Canada. The aim of the paper was to assist critical infrastructure protection and emergency management professionals in assessing the potential impacts of large-scale critical infrastructure disruptions. Information for the study was acquired from Canadian and American media reports and cross-sectoral information sharing with provincial and federal governments and the private sector. The blackout impacted most of the sources and means of generating, transmitting and distributing power within the area, which in turn impacted all critical infrastructure sectors. Landline and cellular companies experienced operational difficulties, which meant that emergency responders were impacted. Newspapers and the electronic media struggled to release information to the public. The banking and finance industry experienced an immediate degradation of services. The power outage caused shipping and storage difficulties for commercial retailers and dairy producers. A number of incidents were reported where only partially treated waste water was released into neighbouring waterways. The timing of the blackout coincided with the closures of workplaces and created additional difficulties on transportation networks. Many gas station pumps were inoperable. Police, fire departments and ambulance services experienced a dramatic increase in the volume of calls received, and all branches of the emergency services sector encountered transportation delays and difficulties with communications equipment. Nuclear reactors were also impacted. An estimated 150,000 Government of Canada employees were unable to report to work. Estimates have indicated that the power outage cost Ontario's economy between $1 and $2 billion. The outage negatively impacted 82 per cent of small businesses in Ontario. 170 refs., 3 figs

Distributed power-line outage detection based on wide area measurement system.

Science.gov (United States)

Zhao, Liang; Song, Wen-Zhan

2014-07-21

In modern power grids, the fast and reliable detection of power-line outages is an important functionality, which prevents cascading failures and facilitates an accurate state estimation to monitor the real-time conditions of the grids. However, most of the existing approaches for outage detection suffer from two drawbacks, namely: (i) high computational complexity; and (ii) relying on a centralized means of implementation. The high computational complexity limits the practical usage of outage detection only for the case of single-line or double-line outages. Meanwhile, the centralized means of implementation raises security and privacy issues. Considering these drawbacks, the present paper proposes a distributed framework, which carries out in-network information processing and only shares estimates on boundaries with the neighboring control areas. This novel framework relies on a convex-relaxed formulation of the line outage detection problem and leverages the alternating direction method of multipliers (ADMM) for its distributed solution. The proposed framework invokes a low computational complexity, requiring only linear and simple matrix-vector operations. We also extend this framework to incorporate the sparse property of the measurement matrix and employ the LSQRalgorithm to enable a warm start, which further accelerates the algorithm. Analysis and simulation tests validate the correctness and effectiveness of the proposed approaches.

Power Allocation and Outage Probability Analysis for SDN-based Radio Access Networks

Science.gov (United States)

Zhao, Yongxu; Chen, Yueyun; Mai, Zhiyuan

2018-01-01

In this paper, performance of Access network Architecture based SDN (Software Defined Network) is analyzed with respect to the power allocation issue. A power allocation scheme PSO-PA (Particle Swarm Optimization-power allocation) algorithm is proposed, the proposed scheme is subjected to constant total power with the objective of minimizing system outage probability. The entire access network resource configuration is controlled by the SDN controller, then it sends the optimized power distribution factor to the base station source node (SN) and the relay node (RN). Simulation results show that the proposed scheme reduces the system outage probability at a low complexity.

Synergistic Use of Nighttime Satellite Data, Electric Utility Infrastructure, and Ambient Population to Improve Power Outage Detections in Urban Areas

Directory of Open Access Journals (Sweden)

Tony A. Cole

2017-03-01

Full Text Available Natural and anthropogenic hazards are frequently responsible for disaster events, leading to damaged physical infrastructure, which can result in loss of electrical power for affected locations. Remotely-sensed, nighttime satellite imagery from the Suomi National Polar-orbiting Partnership (Suomi-NPP Visible Infrared Imaging Radiometer Suite (VIIRS Day/Night Band (DNB can monitor power outages in disaster-affected areas through the identification of missing city lights. When combined with locally-relevant geospatial information, these observations can be used to estimate power outages, defined as geographic locations requiring manual intervention to restore power. In this study, we produced a power outage product based on Suomi-NPP VIIRS DNB observations to estimate power outages following Hurricane Sandy in 2012. This product, combined with known power outage data and ambient population estimates, was then used to predict power outages in a layered, feedforward neural network model. We believe this is the first attempt to synergistically combine such data sources to quantitatively estimate power outages. The VIIRS DNB power outage product was able to identify initial loss of light following Hurricane Sandy, as well as the gradual restoration of electrical power. The neural network model predicted power outages with reasonable spatial accuracy, achieving Pearson coefficients (r between 0.48 and 0.58 across all folds. Our results show promise for producing a continental United States (CONUS- or global-scale power outage monitoring network using satellite imagery and locally-relevant geospatial data.

Operating experience with BWR nuclear power

International Nuclear Information System (INIS)

Bonsdorf, Magnus von.

1986-01-01

The two-unit nuclear power station in Olkiluoto on the western coast of Finland produces about 20 per cent of the electricity consumption of the country. The first unit, TVO-I was first connected to the national grid in September 1978 and TVO-II in February 1980. The original rated power output of each unit was 660 MWe, corresponding to the thermal power of 2000 MW from the reactor. Technical modifications allowed the power to be uprated by 8%. The operating statistics (load factors etc.) are given and the outage experience discussed. The radiological history shows very low radioactivity and dose levels have been maintained at the plant. (UK)

Uprated OMS engine status and future applications

Science.gov (United States)

Boyd, W. C.; Brasher, W. L.

1986-01-01

The baseline Orbital Maneuvering Engine (OME) of the Space Shuttle has the potential for significant performance uprating, leading to increased Shuttle performance capability. The approach to uprating that is being pursued at the NASA Lyndon B. Johnson Space Center is the use of a gas generator-driven turbopump to increase OME operating pressure. A higher pressure engine can have a greater nozzle expansion ratio in the same envelope and at the same thrust level, giving increased engine Isp. The results of trade studies and analyses that have led to the preferred uprated OME configuration are described. The significant accomplishments of a pre-development component demonstration program are also presented, including descriptions of test hardware and discussion of test results. It is shown that testing to date confirms the capability of the preferred uprated OME configuration to meet or exceed performance and life requirements. Potential future activities leading up to a full-scale development program are described, and the capability for the uprated OME to be used in future storable propellant upper stages is discussed.

World-class outage performance of the Olkiluoto nuclear power plant

International Nuclear Information System (INIS)

Paavola, M.

1998-01-01

The production of the Olkiluoto power plant units covered 17% of the electricity consumption in Finland in 1997; the total share of nuclear energy was 27% of the electricity consumed in the country. Based on Finnish experience, nuclear energy is a safe, environmentally friendly and economic way to produce electricity provided that the plants and their personnel are well taken care of. TVO's policy is to keep the plant units in good condition and technically modern. This requires continuous investments in the plant. In maintenance, attention is paid to monitoring the condition of the plant and to preventive maintenance aiming at avoiding disturbances in production. TVO has chosen continuous development as the operational line develops the plant by annual investments and performs the necessary modifications during planned annual outages trying to avoid long production interruptions. The load factors of the Olkiluoto nuclear power plant have been high. The average load factor during the last decade was over 93%. The most significant single factor in the production deficits is the amount or electricity, which has not been produced because of the annual outages. Due to this, special attention has been paid to the performance of the annual outages. TVO aims at continuous development of the annual outage procedure. A centralized task management system makes it possible to perform simultaneously more tasks than before. The company has also invested in equipment and systems, which ease and speed up servicing. Normal outage length varies between 10 and 16 days. By keeping the plant units as modern as possible and in good condition we facilitate reaching TVO's target, which is also stated in TVO's slogan 'always 40 years lifetime'. (author)

C.N. Cofrentes power up-rate up to 110 %. A challenge for cycle 14 core design

International Nuclear Information System (INIS)

Gomez Bernal, M.I.; Lopez Carbonell, M.T.; Garcia Delgado, L.

2001-01-01

C.N.Cofrentes is a GE design BWR reactor with 624 bundles in the core, a rated power of 2894 MWt and it is currently operating Cycle 13 at 104.2 % power. Commercial operation started in 1984 with 12-month cycles at rated power. Both cycle length and thermal power have been increased since then. Power has been up-rated in two steps, first at 102 % in Cycle 4 and later in Cycle 11 at 104.2%. Cycle length has been extended from the original 12-month to the currently 18-month cycles. Next cycle, Cycle 14, will be an 18-month cycle operating at 110 % power. This goal is a challenge for the in-house nuclear design team. Start up for Cycle 14 is planned for the first quarter of 2002. (author)

Use of collaboration software to improve nuclear power plant outage management

Energy Technology Data Exchange (ETDEWEB)

Germain, Shawn

2015-02-01

Nuclear Power Plant (NPP) refueling outages create some of the most challenging activities the utilities face in both tracking and coordinating thousands of activities in a short period of time. Other challenges, including nuclear safety concerns arising from atypical system configurations and resource allocation issues, can create delays and schedule overruns, driving up outage costs. Today the majority of the outage communication is done using processes that do not take advantage of advances in modern technologies that enable enhanced communication, collaboration and information sharing. Some of the common practices include: runners that deliver paper-based requests for approval, radios, telephones, desktop computers, daily schedule printouts, and static whiteboards that are used to display information. Many gains have been made to reduce the challenges facing outage coordinators; however; new opportunities can be realized by utilizing modern technological advancements in communication and information tools that can enhance the collective situational awareness of plant personnel leading to improved decision-making. Ongoing research as part of the Light Water Reactor Sustainability Program (LWRS) has been targeting NPP outage improvement. As part of this research, various applications of collaborative software have been demonstrated through pilot project utility partnerships. Collaboration software can be utilized as part of the larger concept of Computer-Supported Cooperative Work (CSCW). Collaborative software can be used for emergent issue resolution, Outage Control Center (OCC) displays, and schedule monitoring. Use of collaboration software enables outage staff and subject matter experts (SMEs) to view and update critical outage information from any location on site or off.

Outage Performance of Hybrid FSO/RF System with Low-Complexity Power Adaptation

KAUST Repository

Rakia, Tamer

2016-02-26

Hybrid free-space optical (FSO) / radio-frequency (RF) systems have emerged as a promising solution for high data- rate wireless communication systems. We consider truncated channel inversion based power adaptation strategy for coherent and non- coherent hybrid FSO/RF systems, employing an adaptive combining scheme. Specifically, we activate the RF link along with the FSO link when FSO link quality is unacceptable, and adaptively set RF transmission power to ensure constant combined signal-to-noise ratio at receiver terminal. Analytical expressions for the outage probability of the hybrid system with and without power adaptation are derived. Numerical examples show that, the hybrid FSO/RF systems with power adaptation achieve considerable outage performance improvement over conventional hybrid FSO/RF systems without power adaptation. © 2015 IEEE.

Comparison and validation of statistical methods for predicting power outage durations in the event of hurricanes.

Science.gov (United States)

Nateghi, Roshanak; Guikema, Seth D; Quiring, Steven M

2011-12-01

This article compares statistical methods for modeling power outage durations during hurricanes and examines the predictive accuracy of these methods. Being able to make accurate predictions of power outage durations is valuable because the information can be used by utility companies to plan their restoration efforts more efficiently. This information can also help inform customers and public agencies of the expected outage times, enabling better collective response planning, and coordination of restoration efforts for other critical infrastructures that depend on electricity. In the long run, outage duration estimates for future storm scenarios may help utilities and public agencies better allocate risk management resources to balance the disruption from hurricanes with the cost of hardening power systems. We compare the out-of-sample predictive accuracy of five distinct statistical models for estimating power outage duration times caused by Hurricane Ivan in 2004. The methods compared include both regression models (accelerated failure time (AFT) and Cox proportional hazard models (Cox PH)) and data mining techniques (regression trees, Bayesian additive regression trees (BART), and multivariate additive regression splines). We then validate our models against two other hurricanes. Our results indicate that BART yields the best prediction accuracy and that it is possible to predict outage durations with reasonable accuracy. © 2011 Society for Risk Analysis.

Modernization and power increase nuclear power plant Laguna Verde (Mexico)

International Nuclear Information System (INIS)

Garcia-Serrano, J. L.; Merino, A.; Ruiz Gutierrez, L.

2011-01-01

The objective of this project is to perform the modifications on the thermal cycle of the plant required by an Extended Power Uprate, to achieve a safe and reliable operation of the plant at 120% of its original thermal power. The scope includes the design, engineering training, supply of equipment, dismantling, installation, testing and commissioning. The duration of the project is 4 years (82007-2010), and all the modifications have been implemented in four outages, two per unit. The main modification carried out are the change of the condenser, moisture separator and main steam reheaters, the feedwater haters, the turbogenerator and its auxiliaries, transformers, isolated phase bus and main circuit breaker, etc. (Author)

35/30 outage improvement project

International Nuclear Information System (INIS)

Clewett, L.

2011-01-01

Outage performance is a significant contributor to the business plan at Bruce Power. A process improvement initiative commenced in 2010-11 to improve outage efficiency and predictability. 12 teams (over 200 people) participated in improvement identification in four areas: Organizational Engagement; Outage Scope; Resources; and, Critical Outage Execution. Out of over 550 initiatives identified, 200 are being incorporated into the Outage Improvement Initiative. Key deliverables include: Development of a long-range 'fleet-level' business strategy to integrate outage duration, outage improvements and unit refurbishments; Development of a 35 day outage schedule template; Determining optimal outage organization to perform outages on an 8-unit site; Improved schedule adherence and productivity; Process to integrate scope needs to support life-cycle and long-range outage needs improvement while meeting near term and regulatory requirements; Consistent methodology in planning of outages to front-end load the high risk work into the outage schedule; Consistent baseline by senior leaders for the expectations of milestone ownership and completion; Consistent framework for milestone compliance and preparation; Communication strategy to educate personnel on the importance of the outage program and nuclear safety, business goals, and budget; and, Suite of metrics based upon industry benchmarks. The Outage Improvement Initiative has a goal of 35 day outages every 30 months. This potentially represents considerable savings to the Bruce Power business plan, both direct revenue savings attributed to reduced outage duration, as well as incremental outage cost savings. Other improvements from the initiative will include personnel radiation exposure and equipment reliability due to decreased outage duration and adherence to scoping, assessing and long lead part milestones. This presentation will describe the outage improvement initiatives to achieve a goal of consistent 35 day outages

35/30 outage improvement project

Energy Technology Data Exchange (ETDEWEB)

Clewett, L. [Bruce Power, Tiverton, Ontario (Canada)

2011-07-01

Outage performance is a significant contributor to the business plan at Bruce Power. A process improvement initiative commenced in 2010-11 to improve outage efficiency and predictability. 12 teams (over 200 people) participated in improvement identification in four areas: Organizational Engagement; Outage Scope; Resources; and, Critical Outage Execution. Out of over 550 initiatives identified, 200 are being incorporated into the Outage Improvement Initiative. Key deliverables include: Development of a long-range 'fleet-level' business strategy to integrate outage duration, outage improvements and unit refurbishments; Development of a 35 day outage schedule template; Determining optimal outage organization to perform outages on an 8-unit site; Improved schedule adherence and productivity; Process to integrate scope needs to support life-cycle and long-range outage needs improvement while meeting near term and regulatory requirements; Consistent methodology in planning of outages to front-end load the high risk work into the outage schedule; Consistent baseline by senior leaders for the expectations of milestone ownership and completion; Consistent framework for milestone compliance and preparation; Communication strategy to educate personnel on the importance of the outage program and nuclear safety, business goals, and budget; and, Suite of metrics based upon industry benchmarks. The Outage Improvement Initiative has a goal of 35 day outages every 30 months. This potentially represents considerable savings to the Bruce Power business plan, both direct revenue savings attributed to reduced outage duration, as well as incremental outage cost savings. Other improvements from the initiative will include personnel radiation exposure and equipment reliability due to decreased outage duration and adherence to scoping, assessing and long lead part milestones. This presentation will describe the outage improvement initiatives to achieve a goal of consistent 35 day

Refueling outage services in Spanish Nuclear Power Plants

International Nuclear Information System (INIS)

Landete, J. L.; Soto, M.; Nunuez, A.

2007-01-01

DOMINGUIS Group, through its 75 years of business development, has positioned as the Spanish leader Group in Services for the Nuclear Energy and Petrochemical Sectors. In this article, we present the most significant services summary that, through the companies that constitute DOMINGUIS Group, we have developed in Refueling Outage in Spanish Nuclear Power Plants. (Author)

Study on optimization of normal plant outage work plan for nuclear power plants

International Nuclear Information System (INIS)

Aoki, Takayuki; Kodama, Noriko; Takase, Kentaro; Miya, Kenzo

2011-01-01

This paper discusses maintenance optimization in maintenance implementation stage following maintenance planning stage in nuclear power plants and proposes a methodology to get an optimum maintenance work plan. As a result of consideration, the followings were obtained. (1) The quantitative evaluation methodology for optimizing maintenance work plan in nuclear power plants was developed. (2) Utilizing the above methodology, a simulation analysis of maintenance work planning for BWR's PLR and RHR systems in a normal plant outage was performed. Maintenance cost calculation in several cases was carried out on the condition of smoothening man loading over the plant outage schedule as much as possible. (3) As a result of the simulation, the economical work plans having a flat man loading over the plant outage schedule were obtained. (author)

Outage preparation milestones - A tool to improve planned outage performance

International Nuclear Information System (INIS)

Laplatney, Jere; Hwang, Euiyoub

2006-01-01

Sustainable development of Nuclear Energy depends heavily on excellent performance of the existing fleet which in turn depend heavily on the performance of planned outages. Nuclear Power Plants who have successfully undertaken outage optimization projects have demonstrated than an effective Outage Preparation Milestone program is a key component of their improvement programs. This paper will provide background into the field of 'Outage Optimization' including the philosophy, general approach, and results obtained in the U. S. industry. The significant safety improvements afforded by properly implementing outage improvement programs will be explained. Some specific examples of outage improvements will be given including the adoption of a strong Outage Preparation Milestone Program. The paper will then describe the attributes of an effective Outage Preparation Milestone Program and list a set of specific key milestones. The key milestones are defined and the reasons for each are explained. Suggested due dates for each key milestone relative to the outage start date are provided. Successful implementation of an Outage Preparation Milestone program depends heavily upon the management tools and methods used to assure that the organization meets the milestones on time and in a quality fashion. These include methods to handle cases where milestones are not met - either partially or fully. KHNP is investigating implementing an improved Outage Preparation Milestone program for its fleet of reactors as part of its overall program to improve its performance of planned outages

Diablo Canyon refueling outage program

International Nuclear Information System (INIS)

McLane, W.B.; Irving, T.L.

1991-01-01

Management of outages has become one of the most talked about subjects in the nuclear power industry in the past several years. Many utilities do not perform refueling outages very well or in the past have had some outages that they would not like to repeat and in some cases do not even like to think about. With the growing cost of energy and the demands placed on utilities to improve capacity factors, it is very easy for management to focus on shortening refueling outage durations as a prime objective in improving overall corporate performance. So it is with Pacific Gas and Electric Company and the Diablo Canyon power plant. A review of their refueling outage performance reflects a utility that is responding to the nuclear industry's call for improved outage performance

Driving for shorter outages

International Nuclear Information System (INIS)

Tritch, S.

1996-01-01

Nuclear plant outages are necessary to complete activities that cannot be completed during the operating cycle, such as steam generator inspection and testing, refueling, installing modifications, and performing maintenance tests. The time devoted to performing outages is normally the largest contributor to plant unavailability. Similarly, outage costs are a sizable portion of the total plant budget. The scope and quality of work done during outages directly affects operating reliability and the number of unplanned outages. Improved management and planning of outages enhances the margin of safety during the outage and results in increased plant reliability. The detailed planning and in-depth preparation that has become a necessity for driving shorter outage durations has also produced safer outages and improved post-outage reliability. Short outages require both plant and vendor management to focus on all aspects of the outage. Short outage durations, such as 26 days at South Texas or 29 days at North Anna, require power plant inter-department and intra-department teamwork and communication and vendor participation. In this paper shorter and safer outage at the 3-loop plants in the United States are explained. (J.P.N.)

Environmental determinants of unscheduled residential outages in the electrical power distribution of Phoenix, Arizona

International Nuclear Information System (INIS)

Maliszewski, Paul J.; Larson, Elisabeth K.; Perrings, Charles

2012-01-01

The sustainability of power infrastructures depends on their reliability. One test of the reliability of an infrastructure is its ability to function reliably in extreme environmental conditions. Effective planning for reliable electrical systems requires knowledge of unscheduled outage sources, including environmental and social factors. Despite many studies on the vulnerability of infrastructure systems, the effect of interacting environmental and infrastructural conditions on the reliability of urban residential power distribution remains an understudied problem. We model electric interruptions using outage data between the years of 2002 and 2005 across Phoenix, Arizona. Consistent with perceptions of increased exposure, overhead power lines positively correlate with unscheduled outages indicating underground cables are more resistant to failure. In the presence of overhead lines, the interaction between birds and vegetation as well as proximity to nearest desert areas and lakes are positive driving factors explaining much of the variation in unscheduled outages. Closeness to the nearest arterial road and the interaction between housing square footage and temperature are also significantly positive. A spatial error model was found to provide the best fit to the data. Resultant findings are useful for understanding and improving electrical infrastructure reliability. - Highlights: ► Unscheduled outages were related to interacting environmental and infrastructural conditions. ► Underground feeders are more resistant to failure. ► In the presence of overhead lines, birds, vegetation, and proximity to desert areas are positive driving factors. ► Proximity to arterial roads and a proxy for energy demand were significantly positive. ► Outages were most spatially dependent up to around 350 m.

Outage information system

International Nuclear Information System (INIS)

Svengren, Haakan; Meyer, Brita Diskerud

2005-09-01

Today's control room systems are designed to operate during power operation, and there is clearly a need for a system to support control room personnel in automatically supervising the status of the plant during the outage period. In order to improve the supervision of Nuclear Power Plants during outages, three prototypes of the Outage Information system have been designed by the Halden Project, one for PWR and two for BWR. The Outage Information System is presented on a large screen, centrally placed in the control room. There will be a PC connected to manage the system. By using signals from the process as input to logic diagrams reflecting the plant's Safety Technical Specifications, the system automatically is supervising that requirements in Safety Technical Specifications are fulfilled during all plant states of the outage period. The system also automatically gives an overview of the status of safety systems and electrical bus bars. Alarm will occur if a requirement in the Safety Technical Specifications is not fulfilled or if a component planned to be ready for operation, is inoperable. In addition, selected measurements being important during the outage period are presented on the large screen. Which measurements and in which way the values will be presented, depends on the plant's control room design and work practice. (Author)

International outage coding system for nuclear power plants. Results of a co-ordinated research project

International Nuclear Information System (INIS)

2004-05-01

The experience obtained in each individual plant constitutes the most relevant source of information for improving its performance. However, experience of the level of the utility, country and worldwide is also extremely valuable, because there are limitations to what can be learned from in-house experience. But learning from the experience of others is admittedly difficult, if the information is not harmonized. Therefore, such systems should be standardized and applicable to all types of reactors satisfying the needs of the broad set of nuclear power plant operators worldwide and allowing experience to be shared internationally. To cope with the considerable amount of information gathered from nuclear power plants worldwide, it is necessary to codify the information facilitating the identification of causes of outages, systems or component failures. Therefore, the IAEA established a sponsored Co-ordinated Research Project (CRP) on the International Outage Coding System to develop a general, internationally applicable system of coding nuclear power plant outages, providing worldwide nuclear utilities with a standardized tool for reporting outage information. This TECDOC summarizes the results of this CRP and provides information for transformation of the historical outage data into the new coding system, taking into consideration the existing systems for coding nuclear power plant events (WANO, IAEA-IRS and IAEA PRIS) but avoiding duplication of efforts to the maximum possible extent

Economic costs of electrical system instability and power outages caused by snakes on the Island of Guam

Science.gov (United States)

Fritts, T.H.

2002-01-01

The Brown Tree Snake, Boiga irregularis, is an introduced species on Guam where it causes frequent electrical power outages. The snake's high abundance, its propensity for climbing, and use of disturbed habitats all contribute to interruption of Guam's electrical service and the activities that depend on electrical power. Snakes have caused more than 1600 power outages in the 20-yr period of 1978–1997 and most recently nearly 200 outages per year. Single outages spanning the entire island and lasting 8 or more hours are estimated to cost in excess of $3,000,000 in lost productivity, but the costs of outages that involve only parts of the island or those of shorter durations are more difficult to quantify. Costs to the island's economy have exceeded $4.5 M $4.5M"> per year over a 7-yr period without considering repair costs, damage to electrical equipment, and lost revenues. Snakes pose the greatest problem on high voltage transmission lines, on transformers, and inside electrical substations.

Seasonal and Local Characteristics of Lightning Outages of Power Distribution Lines in Hokuriku Area

Science.gov (United States)

Sugimoto, Hitoshi; Shimasaki, Katsuhiko

The proportion of the lightning outages in all outages on Japanese 6.6kV distribution lines is high with approximately 20 percent, and then lightning protections are very important for supply reliability of 6.6kV lines. It is effective for the lightning performance to apply countermeasures in order of the area where a large number of the lightning outages occur. Winter lightning occurs in Hokuriku area, therefore it is also important to understand the seasonal characteristics of the lightning outages. In summer 70 percent of the lightning outages on distribution lines in Hokuriku area were due to sparkover, such as power wire breakings and failures of pole-mounted transformers. However, in winter almost half of lightning-damaged equipments were surge arrester failures. The number of the lightning outages per lightning strokes detected by the lightning location system (LLS) in winter was 4.4 times larger than that in summer. The authors have presumed the occurrence of lightning outages from lightning stroke density, 50% value of lightning current and installation rate of lightning protection equipments and overhead ground wire by multiple regression analysis. The presumed results suggest the local difference in the lightning outages.

On the outage capacity of the block fading channel at low-power regime

KAUST Repository

Rezki, Zouheir

2014-06-01

Outage performance of the M-block fading with additive white Gaussian noise (BF-AWGN) is investigated at low-power regime. We consider delay-constrained constant-rate communications with perfect channel state information (CSI) at both the transmitter and the receiver (CSI-TR), under a short-term power constraint. We show that selection diversity that allocates all the power to the strongest block is asymptotically optimal. Then, we provide a simple characterization of the outage probability in the regime of interest. We quantify the reward due to CSI-TR over the constant-rate constant-power scheme and show that this reward increases with the delay constraint. For instance, for Rayleigh fading, we find that a power gain up to 4.3 dB is achievable. © 2014 IEEE.

APPROACH TO ASSESSING THE PREPAREDNESS OF HOSPITALS TO POWER OUTAGES

Directory of Open Access Journals (Sweden)

Lenka BREHOVSKÁ

2017-06-01

Full Text Available Within the secondary impacts of electricity blackouts, it is necessary to pay attention to facilities providing medical care for the population, namely the hospitals. Hospitals represent a key position in the provision of health care also in times of crisis. These facilities must provide constant care; it is therefore essential that the preparedness of such facilities is kept at a high level. The basic aim of this article is to analyse the preparedness of hospitals to power outages (power failures, blackouts within a pilot study. On that basis, a SWOT analysis is used to determine strengths and weaknesses of the system of preparedness of hospitals to power outages and solutions for better security of hospitals are defined. The sample investigated consists of four hospitals founded by the Regional Authority (hospitals Nos. 1-4 and one hospital founded by the Ministry of Health of the Czech Republic (hospital No. 5. The results of the study shows that most weaknesses of the preparedness of hospitals are represented by inadequately addressed reserves of fuel for the main backup power supply, poor knowledge of employees who are insufficiently retrained, and old backup power supplies (even 35 years in some cases.

Integrated outages increase Surry's availability

International Nuclear Information System (INIS)

Harms, S.R.; Downs, J.L.

1995-01-01

This article describes how, through Virginia Power's and Westinghouse's goal-oriented planning philosophy, teamwork and commitment, average outage duration has decreased significantly. During the past 10 years Virginia Power and its nuclear steam supply system (NSSS) services vendor, Westinghouse Electric Corp., have developed a working partnership with one goal in mind: increasing the availability and capacity factors of the North Anna and Surry nuclear power stations while driving down the operating costs of the plants. The outage integration program, steam generator maintenance agreement (SGMA), and integrated radiological services program form the core of this relationship and helped Virginia Power complete one of the most successful outages in Surry Power Station's operating history

Verification and Enhancement of VIIRS Day-Night Band (DNB) Power Outage Detection Product

Science.gov (United States)

Burke, Angela; Schultz, Lori A.; Omitaomu, Olufemi; Molthan, Andrew L.; Cole, Tony; Griffin, Robert

2017-01-01

This case study of Hurricane Matthew (October 2016) uses the NASA Short-Term Prediction Research and Transition (SPoRT) Center DNB power outage product (using GSFC VIIRS DNB preliminary Black Marble product, Roman et al.. 2017) and 2013 LandScan Global population data to look for correlations between the post-event %-of-normal radiance and the utility company-reported outage numbers (obtained from EAGLE-1).

COMPLETE WASTE MANAGEMENT DURING A POWER UPRATE OUTAGE

International Nuclear Information System (INIS)

Hammel, Lee; Dempsey, Scott

2003-01-01

This paper identifies the advantages of utilizing one vendor to complete the bulk packaging of radioactively contaminated large components and normal Dry Active Waste (DAW) and to provide private rail transportation to direct disposal. This paper will also show the methodologies utilized to achieve a safe, reliable, and cost effective solution while working during critical path evolutions routinely recognized in today's deregulated Utility market

Health and maintenance outages in nuclear power plants: an epidemiological survey

International Nuclear Information System (INIS)

Telle, M.A.; Huez, D.; Niedbala, J.M.; Auclair, J.; Canales, J.P.; Duverge, C.; Forest, H.; Gerondal, M.; Paris, P.M.; Renault, J.C.; Bossevain, L.; Blaise, P.; Blanc, M.C.; Goldberg, M.; Charpak, Y.

1995-01-01

An epidemiological survey, started in 1989, was carried out at the nuclear power plants in the Loire river valley and at Le Blayais (France). Working conditions, work organisation and their impact on health during annual maintenance outages were studied. The main areas covered in this cross-sectional study were: anxiety and symptoms of depression using the Spielberger and CES-D scales. Comparisons were made during both a scheduled outage and in normal operation on four distinct groups of workers, each individual being his own control. A chi-square test was used for the quantitative variables and a test on differences for the quantitative variables. During a unit outage, more frequent overtime and atypical working hours were reported (p<0.01); working rhythms and safety rules were felt as more restrictive and exposure to radiation higher (p<0.01). Detrimental modifications of anxiety and symptoms of depression were observed on controllers whereas expected on maintenance agents. Similar results were observed when considering the rates of outages. Possible readings are given with reference to qualitative studies carried out on this topic, which implies extending our research with both the quantitative and qualitative approaches. (authors). 10 refs., 6 tabs

Replacement power costs due to nuclear-plant outages: a higher standard of care

International Nuclear Information System (INIS)

Gransee, M.F.

1982-01-01

This article examines recent state public utility commission cases that deal with the high costs of replacement power that utilities must purchase after a nuclear power plant outage. Although most commissions have approved such expenses, it may be that there is a trend toward splitting the costs of such expenses between ratepayer and stockholder. Commissions are demanding a management prudence test to determine the cause of the outage and whether it meets the reasonable man standard before allowing these costs to be passed along to ratepayers. Unless the standard is applied with flexibility, however, utility companies could invoke the defenses covering traditional common law negligence

On the outage capacity of the block fading channel at low-power regime

KAUST Repository

Rezki, Zouheir; Alouini, Mohamed-Slim

2014-01-01

the transmitter and the receiver (CSI-TR), under a short-term power constraint. We show that selection diversity that allocates all the power to the strongest block is asymptotically optimal. Then, we provide a simple characterization of the outage probability

Method for estimating power outages and restoration during natural and man-made events

Science.gov (United States)

Omitaomu, Olufemi A.; Fernandez, Steven J.

2016-01-05

A method of modeling electric supply and demand with a data processor in combination with a recordable medium, and for estimating spatial distribution of electric power outages and affected populations. A geographic area is divided into cells to form a matrix. Within the matrix, supply cells are identified as containing electric substations and demand cells are identified as including electricity customers. Demand cells of the matrix are associated with the supply cells as a function of the capacity of each of the supply cells and the proximity and/or electricity demand of each of the demand cells. The method includes estimating a power outage by applying disaster event prediction information to the matrix, and estimating power restoration using the supply and demand cell information of the matrix and standardized and historical restoration information.

Outage Probability Analysis in Power-Beacon Assisted Energy Harvesting Cognitive Relay Wireless Networks

Directory of Open Access Journals (Sweden)

Ngoc Phuc Le

2017-01-01

Full Text Available We study the performance of the secondary relay system in a power-beacon (PB assisted energy harvesting cognitive relay wireless network. In our system model, a secondary source node and a relay node first harvest energy from distributed PBs. Then, the source node transmits its data to the destination node with the help of the relay node. Also, fading coefficients of the links from the PBs to the source node and relay node are assumed independent but not necessarily identically distributed (i.n.i.d Nakagami-m random variables. We derive exact expressions for the power outage probability and the channel outage probability. Based on that, we analyze the total outage probability of the secondary relay system. Asymptotic analysis is also performed, which provides insights into the system behavior. Moreover, we evaluate impacts of the primary network on the performance of the secondary network with respect to the tolerant interference threshold at the primary receiver as well as the interference introduced by the primary transmitter at the secondary source and relay nodes. Simulation results are provided to validate the analysis.

Qinshan CANDU NPP outage performance improvement through benchmarking

International Nuclear Information System (INIS)

Jiang Fuming

2005-01-01

With the increasingly fierce competition in the deregulated Energy Market, the optimization of outage duration has become one of the focal points for the Nuclear Power Plant owners around the world. People are seeking various ways to shorten the outage duration of NPP. Great efforts have been made in the Light Water Reactor (LWR) family with the concept of benchmarking and evaluation, which great reduced the outage duration and improved outage performance. The average capacity factor of LWRs has been greatly improved over the last three decades, which now is close to 90%. CANDU (Pressurized Heavy Water Reactor) stations, with its unique feature of on power refueling, of nuclear fuel remaining in the reactor all through the planned outage, have given raise to more stringent safety requirements during planned outage. In addition, the above feature gives more variations to the critical path of planned outage in different station. In order to benchmarking again the best practices in the CANDU stations, Third Qinshan Nuclear Power Company (TQNPC) have initiated the benchmarking program among the CANDU stations aiming to standardize the outage maintenance windows and optimize the outage duration. The initial benchmarking has resulted the optimization of outage duration in Qinshan CANDU NPP and the formulation of its first long-term outage plan. This paper describes the benchmarking works that have been proven to be useful for optimizing outage duration in Qinshan CANDU NPP, and the vision of further optimize the duration with joint effort from the CANDU community. (authors)

Maintenance and Outage Management Assessment (MOMA)

International Nuclear Information System (INIS)

2005-01-01

The competitive environment has significant implications for nuclear power plant (NPP) operations, which include, inter alia, the need for efficient use of resources and effective management of plant activities of maintenance and outages. The purpose of NPP maintenance and outages is to allow NPPs to use all those functions necessary for safe and reliable power production by keeping them available and adequate maintenance programme is essential. The maintenance programme covers all preventive and remedial measures, both administrative and technical, necessary to identify and mitigate degradation of a functioning system, structure or component, or restore the design functions of a failed system, structure or component to an acceptable level. In response to the needs of MSs, NPES (Nuclear Power Section, Division of Nuclear Power, IAEA) plans to strengthen its services. NPES services will not only continue to provide its 'traditional' products of publications of nuclear industrial best practices and technical implementation of TC projects on plant maintenance and outage management, but also be expanded to deliver, in a timely manner, technical support missions as requested by MSs for NPPs. One of many services is Maintenance and Outage Management Assessment (MOMA). The NPP can obtain support and assistance in assessment and optimisation of its maintenance program and/or outage management. It aims to help the NPP improve its performance of maintenance and outage in a competitive nuclear power business environment. The specific benefits of the assessment are as follows: a) disseminate nuclear industrial best practices on maintenance program and outage management in the world, b) benchmark, evaluate and optimise the approach of maintenance program and outage management and c) identify solutions to known problems at nuclear power plants, if any. MOMA is conducted at the request of NPPs of any IAEA Member States. MOMA consists in a technical mission/visit for 1-3 weeks by

Modernization and power increase nuclear power plant Laguna Verde (Mexico); Modernizacion y aumento de potencia de la central nuclear Laguna Verde (Mexico)

Energy Technology Data Exchange (ETDEWEB)

Garcia-Serrano, J. L.; Merino, A.; Ruiz Gutierrez, L.

2011-07-01

The objective of this project is to perform the modifications on the thermal cycle of the plant required by an Extended Power Uprate, to achieve a safe and reliable operation of the plant at 120% of its original thermal power. The scope includes the design, engineering training, supply of equipment, dismantling, installation, testing and commissioning. The duration of the project is 4 years (82007-2010), and all the modifications have been implemented in four outages, two per unit. The main modification carried out are the change of the condenser, moisture separator and main steam reheaters, the feedwater haters, the turbogenerator and its auxiliaries, transformers, isolated phase bus and main circuit breaker, etc. (Author)

Prediction of power system frequency response after generator outages using neural nets

Energy Technology Data Exchange (ETDEWEB)

Djukanovic, M B; Popovic, D P [Electrotechnicki Inst. ' Nikola Tesla' , Belgrade (Yugoslavia); Sobajic, D J; Pao, Y -H [Case Western Reserve Univ., Cleveland, OH (United States)

1993-09-01

A new methodology is presented for estimating the frequency behaviour of power systems necessary for an indication of under-frequency load shedding in steady-state security assessment. It is well known that large structural disturbances such as generator tripping or load outages can initiate cascading outages, system separation into islands, and even the complete breakup. The approach provides a fairly accurate method of estimating the system average frequency response without making simplifications or neglecting non-linearities and small time constants in the equations of generating units, voltage regulators and turbines. The efficiency of the new procedure is demonstrated using the New England power system model for a series of characteristic perturbations. The validity of the proposed approach is verified by comparison with the simulation of short-term dynamics including effects of control and automatic devices. (author)

Benchmark Report on Key Outage Attributes: An Analysis of Outage Improvement Opportunities and Priorities

Energy Technology Data Exchange (ETDEWEB)

Germain, Shawn St. [Idaho National Laboratory (INL), Idaho Falls, ID (United States); Farris, Ronald [Idaho National Laboratory (INL), Idaho Falls, ID (United States)

2014-09-01

Advanced Outage Control Center (AOCC), is a multi-year pilot project targeted at Nuclear Power Plant (NPP) outage improvement. The purpose of this pilot project is to improve management of NPP outages through the development of an AOCC that is specifically designed to maximize the usefulness of communication and collaboration technologies for outage coordination and problem resolution activities. This report documents the results of a benchmarking effort to evaluate the transferability of technologies demonstrated at Idaho National Laboratory and the primary pilot project partner, Palo Verde Nuclear Generating Station. The initial assumption for this pilot project was that NPPs generally do not take advantage of advanced technology to support outage management activities. Several researchers involved in this pilot project have commercial NPP experience and believed that very little technology has been applied towards outage communication and collaboration. To verify that the technology options researched and demonstrated through this pilot project would in fact have broad application for the US commercial nuclear fleet, and to look for additional outage management best practices, LWRS program researchers visited several additional nuclear facilities.

Guidelines for Implementation of an Advanced Outage Control Center to Improve Outage Coordination, Problem Resolution, and Outage Risk Management

Energy Technology Data Exchange (ETDEWEB)

St. Germain, Shawn W. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Farris, Ronald K. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Whaley, April M. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Medema, Heather D. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Gertman, David I. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2014-09-01

This research effort is a part of the Light-Water Reactor Sustainability (LWRS) Program, which is a research and development (R&D) program sponsored by Department of Energy (DOE) and performed in close collaboration with industry R&D programs that provide the technical foundations for licensing and managing the long-term, safe, and economical operation of current nuclear power plants. The LWRS program serves to help the U.S. nuclear industry adopt new technologies and engineering solutions that facilitate the continued safe operation of the plants and extension of the current operating licenses. The purpose of this research is to improve management of nuclear power plant (NPP) outages through the development of an advanced outage control center (AOCC) that is specifically designed to maximize the usefulness of communication and collaboration technologies for outage coordination and problem resolution activities. This technical report for industry implementation outlines methods and considerations for the establishment of an AOCC. This report provides a process for implementation of a change management plan, evaluation of current outage processes, the selection of technology, and guidance for the implementation of the selected technology. Methods are presented for both adoption of technologies within an existing OCC and for a complete OCC replacement, including human factors considerations for OCC design and setup.

Outage reduction of Hamaoka NPS

International Nuclear Information System (INIS)

Hida, Shigeru; Anma, Minoru

1999-01-01

In the Hamaoka nuclear power plant, we have worked on the outage reduction since 1993. In those days, the outage length in Hamaoka was 80 days or more, and was largely far apart from excellent results of European and American plants about the 30days. A concrete strategy to achieve the reduction process is the extension of working hours, the changing work schedule control unit for every hour, the equipment improvements, and the improvements of work environments, etc. We executed them one by one reflecting results. As a result, we achieved the outage for 57 days in 1995. Starting from this, we acquired the further outage reduction one by one and achieved the outage for 38 days in 1997 while maintaining safety and reliability of the plant. We advance these strategies further and we will aim at the achievement of the 30·35 days outage in the future. (author)

Unit availability not affected by extending outage cycles

Energy Technology Data Exchange (ETDEWEB)

Smith, D.J.

2003-03-01

To improve their economic dispatch position, more and more plant owners are extending the intervals between major outages for boilers from one year to 18-24 months and for steam turbine up to 12 years. In many instances, extended outage cycles have resulted in no loss in availability or increases in forced outages. The article discusses outage scheduling at Tucson Electric Power's Springville coal-fired plant, the Panther Creek Energy Facility in Pennsylvania, and at Tennessee Valley Authority's coal-fired power plants. 1 fig.

WNP-2 outage safety review methodology

International Nuclear Information System (INIS)

Chiang, Albert; Fu, James

2004-01-01

A practical and versatile method was developed in the flow chart and checklist forms to show the defense-in-depth for various key safety functions of a nuclear power plant during shutdown. Using four different colors (green, yellow, orange, and red) for indication of levels of defense-in-depth is visually impressive, easy to understand, and was adopted by the outage management personnel as a convenient reference tool for maintenance activity planning before the outage, and schedule changes during the outage. This paper describes the method and its application at Washington Public Power Supply System's Nuclear Project 2 (WNP-2). (author)

Monitoring Disaster-Related Power Outages Using NASA Black Marble Nighttime Light Product

Science.gov (United States)

Wang, Z.; Román, M. O.; Sun, Q.; Molthan, A. L.; Schultz, L. A.; Kalb, V. L.

2018-04-01

Timely and accurate monitoring of disruptions to the electricity grid, including the magnitude, spatial extent, timing, and duration of net power losses, is needed to improve situational awareness of disaster response and long-term recovery efforts. Satellite-derived Nighttime Lights (NTL) provide an indication of human activity patterns and have been successfully used to monitor disaster-related power outages. The global 500 m spatial resolution National Aeronautics and Space Administration (NASA) Black Marble NTL daily standard product suite (VNP46) is generated from Visible Infrared Imaging Radiometer Suite (VIIRS) Day/Night Band (DNB) onboard the NASA/National Oceanic and Atmospheric Administration (NOAA) Suomi National Polar-orbiting Partnership (Suomi- NPP) satellite, which began operations on 19 January 2012. With its improvements in product accuracy (including critical atmospheric and BRDF correction routines), the VIIRS daily Black Mable product enables systematic monitoring of outage conditions across all stages of the disaster management cycle.

Control Room Tasks During Refueling in Ringhals 1 Nuclear Power Plant - Operator performance during refuelling outages

International Nuclear Information System (INIS)

Stroebeck, Einar; Olausson, Jesper; Van Gemst, Paul

1998-01-01

This paper discusses the performance and tasks of the operators in the control room during refuelling outages. Analyses of such events have, during the last years, shown that the risk for nuclear accidents is not negligible compared with the risk at higher reactor power levels. Some experts have the opinion that, due to mistakes during an outage, the risk for such accidents during the outage and other accidents later on during power operation is higher than in other plant situations. The high risk level is mainly a result of errors at maintenance actions and supervision of lining up of safety systems. Most of the control rooms in existing NPPs were designed more than 10 years ago. At that time the activities and the tasks for the operators were not very well understood. Procedures for refuelling and other activities during the outages were not described very well. Often the utility organisation for refuelling outages was not established at the start of the control room design. Experience from operation during many years has shown that the performance of operators can be improved in existing plant, and thus risks be reduced, by upgrading the control room. These issues have been studied as a part of the modernisation project for Ringhals 1, an ABB Atom BWR owned by Vattenfall AB in Sweden. The paper will describe the working model for upgrading the control room and important issues to take care of with respect to refuelling outages. The identified issues will be used as the input for improving control room philosophy and the individual technical systems. (authors)

Outages planning

International Nuclear Information System (INIS)

Blanquer, N.

2010-01-01

The reason of a nuclear power plant outage seems easy. Replace 1/3 of the total core fuel inside reactor for a new, store the old one in a pool and shuffle the rest 2/3 in other positions in the core to optimize fuel burn up. Also is needed to make the preventive, corrective and conservative maintenance, the selected design changes and the regulatory and technical requirements for equipment and systems. To make the plant outage strategy for all the above pack with nuclear safety not challenged is the objective of this article for the Spanish Nuclear Society magazine. (Author)

Outage Analysis of Cooperative Transmission with Energy Harvesting Relay: Time Switching versus Power Splitting

Directory of Open Access Journals (Sweden)

Guanyao Du

2015-01-01

Full Text Available This paper investigates the multiuser transmission network with an energy harvesting (EH cooperative relay, where a source transmits independent information to multiple destinations with the help of an energy constrained relay. The relay can harvest energy from the radio frequency (RF signals transmitted from the source, and it helps the multiuser transmission only by consuming the harvested energy. By adopting the time switching and the power splitting relay receiver architectures, we firstly propose two protocols, the time switching cooperative multiuser transmission (TSCMT protocol and the power splitting cooperative multiuser transmission (PSCMT protocol, to enable the simultaneous information processing and EH at the relay for the system. To evaluate the system performance, we theoretically analyze the system outage probability for the two proposed protocols and then derive explicit expressions for each of them, respectively. Numerical results are provided to demonstrate the accuracy of our analytical results and reveal that compared with traditional noncooperative scheme our proposed protocols are green solutions to offer reliable communication and lower system outage probability without consuming additional energy. In particular, for the same transmit power at the source, the PSCMT protocol is superior to the TSCMT protocol to obtain lower system outage probability.

The costs of power outages: A case study from Cyprus

International Nuclear Information System (INIS)

Zachariadis, Theodoros; Poullikkas, Andreas

2012-01-01

We study the costs of electricity disruptions in Cyprus, which suffered severe power shortages in summer 2011 after an explosion that destroyed 60% of its power generating capacity. We employ both economic and engineering approaches to assess these costs. Among other calculations, we provide estimates of the value of lost load by economic sector and the hourly value of electricity by season and type of day. The results of two economic methods employed to assess welfare losses differ largely, indicating that the assessment of outage costs is associated with many uncertainties. Our calculations show that the emergency actions taken by national energy authorities in response to that accident, though not necessarily optimal, have generally been appropriate and in line with international best practices: the additional costs incurred due to these measures are lower than the economic losses avoided thanks to these actions. Preferential treatment of specific consumer types in the case of repeated power outages remains an open policy question. - Highlights: ► We evaluate the response of energy authorities to a sudden electricity crisis. ► We combine two top-down economic methods and a bottom-up engineering approach. ► We estimate the value of lost electricity by hour, day type and season. ► The response of energy authorities turned out to be effective. ► Costs of emergency actions were lower than the economic losses avoided.

Study on European Nuclear Safety Practices during Planned Outages at Nuclear Power Plants

International Nuclear Information System (INIS)

2001-12-01

The present project was aimed at providing: a description of the current status of nuclear safety practices during planned outages at nuclear power plants followed in Europe; the criteria for the safety analysis of future reactors at the design stage; proposing a set of recommendations on good practices and criteria leading to the improvement of nuclear safety during those conditions. The work was organised in 3 phases: Collecting data on current practices; Analysis of questionnaire answers and drawing up of safety good practices references and recommendations; Collecting relevant ideas related to the future reactors at design stage (European Pressurised Water Reactor, European Passive Plant project, European Utilities Requirements and Utilities Requirement Document project). The key element of the performed work was the detailed questionnaire, based on bibliographical review, expert experience and outage practices available in the working team. Different safety areas and activities were covered: outage context; nuclear safety; outage strategy, organisation and control; operating feedback; use of Probabilistic Safety Assessment. The questionnaire was answered by 12 European nuclear power plants, representing 9 different European countries and three different types of reactors (Pressurised Water Reactor, Boiling Water Reactor and Water Water Energy Reactor). Conclusions were drawn under the following headers: Organisational survey and generalities Organisational effectiveness Quality of maintenance Quality of operation Engineering support, management of modification Specific aspects Each analysed subject includes the following topics: Questions background with a summary and the aim of the questions. Current status, that describes common practices, as derived from the answers to the questionnaire, and some examples of good specific practices. Identified good practices. (author)

The Modernization Program and Power Up-rate at NPP V2 Jaslovske Bohunice, Slovak Republic

International Nuclear Information System (INIS)

Reznik, Vladivoj; Krajmer, Imrich

2010-01-01

Slovenske Elektrarne, a.s. is a second largest utility company in the Central and Eastern Europe that owns an optimal production portfolio comprised of nuclear, thermal and hydroelectric power plants. There are two nuclear power plants Bohunice and Mochovce both operate with two units and another two units Mochovce 3 and 4 are currently under construction. Electricity at Nuclear power plant Bohunice V2 is generated by two 440 MW units that had gradually been connected to the power network over the period between 1984 and 1985. In the construction of the nuclear power plant V2 the concept of pressurized water reactors was adopted and the Soviet-era design WWER 440 used. The upgrading of Nuclear Power Plant Bohunice V2 is based on three main points: Modernization, Power up-rate, and Ageing monitoring program. The main targets of the modernization project were: Increasing of the Nuclear Safety and of the Nuclear operational reliability, and Seismic improvement. This modernization program is in full compliance with IAEA requirements and with the decisions from the Nuclear Regulatory Agency of the Slovak Republic (UJD) and achievement of the probabilistic safety criteria in accordance with IAEA recommendations. Except that is ensured a safe, reliable, economical and effective electricity and heat generation. Achieved results are based for further prolongation of the operation life time up to 60 years. (authors)

Outage costs: who should pay?

International Nuclear Information System (INIS)

Stivison, D.V.

1986-01-01

Decisions affecting the Three Mile Island-1 and -2 reactors illustrate new an stricter standards which apply to how regulator will allocate the costs of outages. The rule allows outages for normal refueling and other normal shutdowns if return to the power grid is assured. TMI-1 was removed from the rate base one year after the accident, and was readmitted only after achieving full power in 1986. A reasonableness standard based on an analysis of the outage and utility responses is the basis for deciding for or against removal. The author cites cases in which unreasonable actions caused the Nuclear Regulatory Commission to charge utility management with imprudence. New safety standards will force utilities to reduce employee error, equipment failure, and management weakness. 19 references

Modernization of turbines in nuclear power plants

International Nuclear Information System (INIS)

Harig, T.

2005-01-01

An ongoing goal in the power generation industry is to maximize the output of currently installed assets. This is most important at nuclear power plants due to the large capital investments that went into these plants and their base loaded service demands. Recent trends in the United States show a majority of nuclear plants are either obtaining, or are in the process of obtaining NRC approvals for operating license extensions and power uprates. This trend is evident in other countries as well. For example, all Swedish nuclear power plants are currently working on projects to extend their service life and maximize capacity through thermal uprate and turbine-generator upgrade with newest technology. The replacement of key components with improved ones is a means of optimizing the service life and availability of power plants. Economic advantages result from increased efficiency, higher output, shorter startup and shutdown times as well as reduced outage times and service costs. The rapid advances over recent years in the development of calculation programs enables adaptation of the latest blading technology to the special requirements imposed by steam turbine upgrading. This results in significant potential for generating additional output with the implementation of new technology, even without increased thermal power. In contrast to maintenance and investment in pure replacement or repair of a component with the primary goal of maintaining operability and reliability, the additional output gained by upgrading enables a return on investment to be reaped. (orig.)

MONITORING DISASTER-RELATED POWER OUTAGES USING NASA BLACK MARBLE NIGHTTIME LIGHT PRODUCT

Directory of Open Access Journals (Sweden)

Z. Wang

2018-04-01

Full Text Available Timely and accurate monitoring of disruptions to the electricity grid, including the magnitude, spatial extent, timing, and duration of net power losses, is needed to improve situational awareness of disaster response and long-term recovery efforts. Satellite-derived Nighttime Lights (NTL provide an indication of human activity patterns and have been successfully used to monitor disaster-related power outages. The global 500 m spatial resolution National Aeronautics and Space Administration (NASA Black Marble NTL daily standard product suite (VNP46 is generated from Visible Infrared Imaging Radiometer Suite (VIIRS Day/Night Band (DNB onboard the NASA/National Oceanic and Atmospheric Administration (NOAA Suomi National Polar-orbiting Partnership (Suomi- NPP satellite, which began operations on 19 January 2012. With its improvements in product accuracy (including critical atmospheric and BRDF correction routines, the VIIRS daily Black Mable product enables systematic monitoring of outage conditions across all stages of the disaster management cycle.

Partnership - its contribution to outage success

International Nuclear Information System (INIS)

Gill, K.S.; Kirton-Darling, F.; Robinson, F.T.

1996-01-01

An innovative approach to developing the teamwork between the power station and the outage contractor has been pioneered over the past three years at the Bradwell nuclear power station in the UK, which houses two Magnox reactors. Magnox Electric and Rolls-Royce Nuclear Engineering Services are now undertaking their third outage under a partnership contract which has provided significant benefits to both parties. (Author)

Nuclear Plant Integrated Outage Management

International Nuclear Information System (INIS)

Gerstberger, C. R.; Coulehan, R. J.; Tench, W. A.

1992-01-01

This paper is a discussion of an emerging concept for improving nuclear plant outage performance - integrated outage management. The paper begins with an explanation of what the concept encompasses, including a scope definition of the service and descriptions of the organization structure, various team functions, and vendor/customer relationships. The evolvement of traditional base scope services to the integrated outage concept is addressed and includes discussions on changing customer needs, shared risks, and a partnership approach to outages. Experiences with concept implementation from a single service in 1984 to the current volume of integrated outage management presented in this paper. We at Westinghouse believe that the operators of nuclear power plants will continue to be aggressively challenged in the next decade to improve the operating and financial performance of their units. More and more customers in the U. S. are looking towards integrated outage as the way to meet these challenges of the 1990s, an arrangement that is best implemented through a long-term partnering with a single-source supplier of high quality nuclear and turbine generator outage services. This availability, and other important parameters

Refueling outage data collection and analysis

International Nuclear Information System (INIS)

Harshaw, K.; Quilliam, J.; Brinsfield, W.; Jeffries, J.

1993-07-01

This report summarizes the results of an EPRI project to compile an industry generic refueling outage database applicable to alternate (non-full-power) modes of shutdown conditions at nuclear power plants. The project team evaluated five outages at two BWR plants. They obtained data primarily from control room logs, outage schedules, incident reports, and licensee event reports. The team organized the data by outage segment and time line. Due to its small sample size, this study produced no conclusive results related to initiating event frequencies, equipment failure rates, or human reliability estimates during shutdown conditions. However, it pointed out the problems of brief or inconsistent recordkeeping. A too brief record results in difficulty determining if the root cause of an event was mechanical or the result of human performance. Retrieval of data can be difficult and labor-intensive. There is a clear need for better, more comprehensive documentation

Review of Paks outage results 1990

International Nuclear Information System (INIS)

Lukacs, P.; Zsoldos, F.; Kiss, Z.

1991-01-01

The year 1990 was not the most successful from an outage point of view at the Paks Nuclear Power Plant in Hungary -there were one or two long delays. Work at unit 4 had a delay of 10 days because of an error made during assembling the reactor vessel. While the outage of unit 3 was running, a feedwater pipe hanger problem was discovered - several hangers were found displaced from the right position. A general inspection of the affected system was required and this took about 11 days. Information about each outage is presented on diagrams, making comparison easier. These diagrams give information about deviations from the outage plan, about work hours performed during outages, and about collective exposure. (author)

Psychosocial work strain of maintenance personnel during annual outage and normal operation in a nuclear power plant

International Nuclear Information System (INIS)

Jacobsson, L.; Svensson, O.

1991-01-01

This paper reports on a study which evaluates psychosocial work demands during the annual outage for a maintenance work group in a nuclear power plant. The study is based on a stress paradigm and it has been asserted that increased work strain would have a negative effect on performance. Nineteen workers, aged 20-55 years, participated in the study. The subjects filled out a questionnaire comparing work strain during annual outage and normal operation. During the outage period a 3-shift 24-hour work schedule, including nightwork, was used (working hours during normal operation was 7-16). Increased demands on concentration and vigilance, increased time pressure and strain on social relations within the group were found to characterize work during annual outage. Interestingly, for specific work tasks an association was found between the risk of making errors and high psychological workload. Increased work strain, shiftwork including nightwork and reduced social support are important psychosocial risk factors that might contribute to human error during the outage period

Long-term optimization of outage performance

International Nuclear Information System (INIS)

Huemmeler, Alexander; Jakobs, Norbert; Seifert, Siegfried

2003-01-01

Deregulation of the power markets and the accompanying pressure on electricity prices have forced all electric utilities to reduce their power generating costs in order to be able to hold their own in the new market environment. This has also particularly affected the operators of nuclear power plants since they have to compete against the lower power generating costs of fossil-fired combined-cycle power plants and, in Germany are faced with a difficult political climate. The areas identified as having the greatest cost-cutting potential were fuel costs, operating costs and measures to increase plant availability. The main objective behind increasing plant availability was not only to improve the already high standard of operational reliability and plant safety even further, but also to significantly shorten the downtime needed for annual refueling outages. A variety of measures aimed at shortening scheduled plant outages have thus been developed and successfully implemented by nuclear plant operators. At the same time, process improvements and new technologies have been introduced by the service providers. Both initiatives together have contributed towards substantially reducing outage time and cost. (author)

Qualification of FFA treatment for the water-steam cycle as an innovative lay-up strategy for the long term outage of a CANDU-6 reactor

International Nuclear Information System (INIS)

Ramminger, Ute; Fandrich, Jörg; Sainz, Ricardo; Ovando, Luis; Herrera, Cecilia; Mendizabal, Maribel; Dumon, Adriana; Chocron, Mauricio

2014-01-01

The majority of worldwide operating Nuclear Power Plants is older than 25 years, which is accompanied with extended outage duration due to large refurbishment and upgrade programs, e.g. Steam Generator Replacement and other large component replacement. For these long term outages adequate and cost effective preservation methods are required. Normally during outages, systems and components are drained and opened to atmosphere whereas wet surfaces and moisture condensation can result in uniform corrosion of carbon steel and eventually other materials; superimposed localized corrosion is possible in presence of impurities. For those systems there are in general two different lay-up methods possible. Dry lay-up by removing all water and humidity from the components or wet lay-up with demineralized and oxygen free water and additional corrosion inhibitors. Disadvantages of these lay-up methods are: High man power and hardware efforts for performing dry lay-up. Usage of hazardous chemicals like Hydrazine. Insufficient results of both lay-up methods in case of switching between dry and wet lay-up. To improve the lay-up concept for long term outages, AREVA GmbH developed an innovative concept using FFA (Film-Forming Amines) for secondary side system lay-up. The entire water-steam cycle including the Steam Generators is treated in one step without any negative impact on the treated structural materials. This technology has been applied for the first time at NPP Embalse. Embalse Nuclear Power Station consists of a CANDU-6 reactor of 648 MWe electrical output. It is in commercial operation since 1984. The shutdown for refurbishment and preparation for the second cycle of operation that includes among other tasks the replacement of the existing steam generators and power uprating has been scheduled for 2014, which causes the necessity of a lay-up optimization in the plant. This paper deals in detail with the qualification process of the FFA treatment considering the specifics

Braess's paradox in oscillator networks, desynchronization and power outage

International Nuclear Information System (INIS)

Witthaut, Dirk; Timme, Marc

2012-01-01

Robust synchronization is essential to ensure the stable operation of many complex networked systems such as electric power grids. Increasing energy demands and more strongly distributing power sources raise the question of where to add new connection lines to the already existing grid. Here we study how the addition of individual links impacts the emergence of synchrony in oscillator networks that model power grids on coarse scales. We reveal that adding new links may not only promote but also destroy synchrony and link this counter-intuitive phenomenon to Braess's paradox known for traffic networks. We analytically uncover its underlying mechanism in an elementary grid example, trace its origin to geometric frustration in phase oscillators, and show that it generically occurs across a wide range of systems. As an important consequence, upgrading the grid requires particular care when adding new connections because some may destabilize the synchronization of the grid—and thus induce power outages. (paper)

Contingency Analysis of Cascading Line Outage Events

Energy Technology Data Exchange (ETDEWEB)

Thomas L Baldwin; Magdy S Tawfik; Miles McQueen

2011-03-01

As the US power systems continue to increase in size and complexity, including the growth of smart grids, larger blackouts due to cascading outages become more likely. Grid congestion is often associated with a cascading collapse leading to a major blackout. Such a collapse is characterized by a self-sustaining sequence of line outages followed by a topology breakup of the network. This paper addresses the implementation and testing of a process for N-k contingency analysis and sequential cascading outage simulation in order to identify potential cascading modes. A modeling approach described in this paper offers a unique capability to identify initiating events that may lead to cascading outages. It predicts the development of cascading events by identifying and visualizing potential cascading tiers. The proposed approach was implemented using a 328-bus simplified SERC power system network. The results of the study indicate that initiating events and possible cascading chains may be identified, ranked and visualized. This approach may be used to improve the reliability of a transmission grid and reduce its vulnerability to cascading outages.

Renovation and uprating of seven hydropower plants in Java

International Nuclear Information System (INIS)

Nuessli, W.

1991-01-01

The Indonesian Power Authority is planning to renovate and uprate seven hydropower stations in Java to expand plant life expectancy, ensure operating safety and reliability, and increase power and generation within economical limits. The power plants were constructed in the early 1920s and extended between 1945 and 1950. Their capacities vary between 4 and 20 MW. For the renovation project, Colenco Power Consulting Ltd. is acting as a consultant to PLN. In February 1990, Colenco inspected all seven power plants. The results of the inspections served as the basis for the development of renovation plans for each of the seven hydropower plants. To determine the cost of the proposed renovation plans, appraisers had to determine a method for comparing the value of an existing plant to that of a renovated one. The two different evaluation methods used for these comparisons are the focus of this paper

Partnership - the heart of integrated outage management

International Nuclear Information System (INIS)

Robinson, F.T.

1995-01-01

Changes in the power generating industry continue apace. The effects of privatisation are widely visible: nowhere more so than in the growing national and international competition facing the generators around the world. A successful, long-term marriage between generator and contractor on power station outage management offers significant scope for cost reduction, shortening annual plant downtime and generating more megawatts, all within a safety environment of continuous improvement. Working in close partnership, Nuclear Electric and Rolls-Royce Nuclear Engineering Services have remodelled the whole contractor/client strategy. The new discipline, known as integrated outage management and partnering, is already producing shorter outage periods at Bradwell, a Magnox Station in Essex. (author)

Lessons learned in planning ALARA/health physics support for major nuclear power plant outages

International Nuclear Information System (INIS)

Gilman, T.R.; Lesinski, M.L.

1987-01-01

Although as low as reasonably achievable (ALARA)/health physics is viewed as necessary support for nuclear power plant outage work, it can be the last area to which attention is given in preparing for a large-scope outage. Inadequate lead times cause last-minute preparations resulting in delays in planned work. The Dresden Unit 3 Recirculation Piping Replacement Project is examined from a planning viewpoint. The attention that was given the various areas of a comprehensive ALARA/health physics program is examined, and approximate recommended lead times are discussed. The discussion will follow a chronological path from project inception to the beginning stages of outage work. Initially, the scope of work needs to be assessed by individuals familiar with similar projects of equivalent magnitude. Those individuals need to be health physics professionals who understand the particular utility and/or the site's way of doing business. They should also possess a good understanding of preferred industry practices

Placement of Synchronized Measurements for Power System Observability during Cascaded Outages

Science.gov (United States)

Thirugnanasambandam, Venkatesh; Jain, Trapti

2017-11-01

Cascaded outages often result in power system islanding followed by a blackout and therefore considered as a severe disturbance. Maintaining the observability of each island may help in taking proper control actions to preserve the stability of individual islands thus, averting system collapse. With this intent, a strategy for placement of synchronized measurements, which can be obtained from phasor measurement units (PMU), has been proposed in this paper to keep the system observable during cascaded outages also. Since, all the cascaded failures may not lead to islanding situations, therefore, failures leading to islanding as well as non-islanding situations have been considered. A topology based algorithm has been developed to identify the islanding/non-islanding condition created by a particular cascaded event. Additional contingencies such as single line loss and single PMU failure have also been considered after the occurrence of cascaded events. The proposed method is further extended to incorporate the measurement redundancy, which is desirable for a reliable state estimation. The proposed scheme is tested on IEEE 14-bus, IEEE 30-bus and a practical Indian 246-bus networks. The numerical results ensure the observability of the power system under system intact as well as during cascaded islanding and non-islanding disturbances.

Outages of electric power supply resulting from cable failures Boston Edison Company system

Energy Technology Data Exchange (ETDEWEB)

None

1980-07-01

Factual data are provided regarding 5 electric power supply interruptions that occurred in the Boston Metropolitan area during April to June, 1979. Common to all of these outages was the failure of an underground cable as the initiating event, followed by multiple equipment failures. There was significant variation in the voltage ratings and types of cables which failed. The investigation was unable to delineate a single specific Boston Edison design operating or maintenance practice that could be cited as the cause of the outages. After reviewing the investigative report the following actions were recommended: the development and implementation of a plan to eliminate the direct current cable network; develop a network outage restoration plan; regroup primary feeder cables wherever possible to minimize the number of circuits in manholes, and to separate feeders to high load density areas; develop a program to detect incipient cable faults; evaluate the separation of the north and south sections of Back Bay network into separate networks; and, as a minimum, install the necessary facilities to make it possible to re-energize one section without interfering with the other; and re-evaluate the cathodic protection scheme where necessary. (LCL)

Spatial generalized linear mixed models of electric power outages due to hurricanes and ice storms

International Nuclear Information System (INIS)

Liu Haibin; Davidson, Rachel A.; Apanasovich, Tatiyana V.

2008-01-01

This paper presents new statistical models that predict the number of hurricane- and ice storm-related electric power outages likely to occur in each 3 kmx3 km grid cell in a region. The models are based on a large database of recent outages experienced by three major East Coast power companies in six hurricanes and eight ice storms. A spatial generalized linear mixed modeling (GLMM) approach was used in which spatial correlation is incorporated through random effects. Models were fitted using a composite likelihood approach and the covariance matrix was estimated empirically. A simulation study was conducted to test the model estimation procedure, and model training, validation, and testing were done to select the best models and assess their predictive power. The final hurricane model includes number of protective devices, maximum gust wind speed, hurricane indicator, and company indicator covariates. The final ice storm model includes number of protective devices, ice thickness, and ice storm indicator covariates. The models should be useful for power companies as they plan for future storms. The statistical modeling approach offers a new way to assess the reliability of electric power and other infrastructure systems in extreme events

Power plant and utility performance: how world-record outages are being achieved in the USA

International Nuclear Information System (INIS)

Anon.

1997-01-01

Two record-breaking refuelling outages at power reactors in the USA are described. The first, at Browns Ferry 3 BWR, was accomplished in 19 days 39 minutes - a shorter time than for an General Electric BWR anywhere in the world hitherto. The management attribute this success to planning, personnel and performance. As well as refuelling, inspections and maintenance, major modifications were carried out. These included the completion of the installation of digital feedwater reactor level control and digital feedwater heater level control. The second outage, at South Texas Project 2 BWR, at 17 days 14 hours and 10 minutes was the fastest yet recorded for any US nuclear unit. This achievement is ascribed to excellent outage preparation and scheduling, the superior condition of the plant equipment and teamwork and safety consciousness on behalf of the plant personnel. Finally, brief consideration is given to the nuclear performance recovery programme of Commonwealth Edison and Ontario Hydro Nuclear. (UK)

The control of reactor outages

International Nuclear Information System (INIS)

Bouget, Y.H.; Berteloot, J.M.

1995-01-01

The 1985-1992 period was marked by a continuous decay in French reactors operation. This situation has led the Committee for Outages Mastery to take steps for the improvement of nuclear power plants availability. The control of reactor outages requires an integrated vision of the safety, duration, dosimetry, costs and security aspects and a perfect management of contractors. The paper describes the methodology used for the management and the maintenance of the French PWR reactors stock. A detailed schedule of maintenance tasks with dose estimations is now required from each site to anticipate and optimize the duration of outages. Thanks to this action, a significant reduction of the maintenance costs is observed for the 1992-1995 period. (J.S.). 2 figs

Analysis of T101 outage radiation dose

International Nuclear Information System (INIS)

Li, Zhonghua

2008-01-01

Full text: Collective radiation dose during outage is about 80% of annual collective radiation dose at nuclear power plants (NPPs). T 101 Outage is the first four-year outage of Unit 1 at Tianwan Nuclear Power Station (TNPS) and thorough overhaul was undergone for the 105-day's duration. Therefore, T 101 Outage has significant reference meaning to reducing collective radiation dose at TNPS. This paper collects the radiation dose statistics during T 101 Outage and analyses the radiation dose distribution according to tasks, work kinds and varying trend of the collective radiation dose etc., comparing with other similar PWRs in the world. Based on the analysis this paper attempts to find out the major factors in collective radiation dose during T 101 Outage. The major positive factor is low radiation level at workplace, which profits from low content of Co in reactor construction materials, optimised high-temperature p H value of the primary circuit coolant within the tight range and reactor operation without trips within the first fuel cycle. One of the most negative factors is long outage duration and many person-hours spent in the radiological controlled zone, caused by too many tasks and inefficient work. So besides keeping good performance of reducing radioactive sources, it should be focused on how to improve implementation of work management including work selection, planning and scheduling, work preparation, work implementation, work assessment and feedback, which can lead to reduced numbers of workers needed to perform a task, of person-hours spent in the radiological controlled zone. Moreover, this leads to reduce occupational exposures in an ALARA fashion. (author)

Nuclear outages: an approach to project controls

International Nuclear Information System (INIS)

Bryson, R.

1985-01-01

The annual budget for maintaining and operating a nuclear power plant has risen dramatically over the past 5 years. NRC-mandated plant improvements and outage related expenses are often cited to be the main contributors to these escalating budgets. Nuclear utilities have responded by developing programs to improve plant availability and outage costs through improved outage performance. Utilities recognize that for capital improvements the program to control costs does no begin with outage planning, but rather more appropriately up front during the engineering phase. To support their management objectives, utilities have been developing comprehensive project control systems for concurrently reducing capital expenditures, outage-related costs, and time. This paper provides an approach to project controls that, rather than using one all inclusive comprehensive system, requires five separate monitoring systems - one for each phase of an activity's life cycle. Through the integration of these discrete but interrelated systems, utility management acquires the necessary tools for comprehensive planning and control of their modification program and effective detailed monitoring for all outage-related activities

On Outage Performance of Spectrum-Sharing Communication over M-Block Fading

KAUST Repository

Alabbasi, AbdulRahman

2015-12-06

In this paper, we consider a cognitive radio system in which a block-fading channel is assumed. Each transmission frame consists of M blocks and each block undergoes a different channel gain. Instantaneous channel state information about the interference links remains unknown to the primary and secondary users. We minimize the secondary user\\'s targeted outage probability over the block-fading channels. To protect the primary user, a statistical constraint on its targeted outage probability is enforced. The secondary user\\'s targeted outage region and the corresponding optimal power are derived. We also propose two sub-optimal power strategies and derive compact expressions for the corresponding outage probabilities. These probabilities are shown to be asymptotic lower and upper bounds on the outage probability. Utilizing these bounds, we derive the exact diversity order of the secondary user outage probability. Selected numerical results are presented to characterize the system\\'s behavior.

Outage planning in nuclear power plants. A paradigm shift from an external towards an integrated project planning tool

Energy Technology Data Exchange (ETDEWEB)

Rosemann, Andreas [Gesellschaft fuer integrierte Systemplanung (GiS) mbH, Weinheim (Germany)

2014-05-15

In nuclear power plants it is common to carry out the technical planning of the annual outage work orders in an Enterprise Application Management (EAM) system and to schedule the outage tasks in a project planning tool. The reason for this is historical: Former EAM systems did not (or just to some extend) offer the necessary functionalities to realise the scheduling of the outage; graphical support for the planning was not provided at all. Consequently, scheduling the annual outage was performed in a separate planning tool. Modern Enterprise Application Management (EAM) software builds on established project planning tools with respect to the functionalities and timing of work orders. As a standard they provide editable charts as well as a lot of functionalities which are required for scheduling the annual outage. The functional gap between the demanded planning functionalities and the functionalities provided by the EAM system has been significantly reduced. Depending on the deployed software itself it is possible to extend the EAM system with little effort (in comparison to the promising advantages) so that external project timing planning tools are not required any more. By shifting towards an integrated planning tool, efficiency in planning an outage as well as the quality of communication of the current planning status increases. Furthermore, the basis of information for work orders by the control room staff and therefore safety can be enhanced. (orig.)

Outage planning in nuclear power plants. A paradigm shift from an external towards an integrated project planning tool

International Nuclear Information System (INIS)

Rosemann, Andreas

2014-01-01

In nuclear power plants it is common to carry out the technical planning of the annual outage work orders in an Enterprise Application Management (EAM) system and to schedule the outage tasks in a project planning tool. The reason for this is historical: Former EAM systems did not (or just to some extend) offer the necessary functionalities to realise the scheduling of the outage; graphical support for the planning was not provided at all. Consequently, scheduling the annual outage was performed in a separate planning tool. Modern Enterprise Application Management (EAM) software builds on established project planning tools with respect to the functionalities and timing of work orders. As a standard they provide editable charts as well as a lot of functionalities which are required for scheduling the annual outage. The functional gap between the demanded planning functionalities and the functionalities provided by the EAM system has been significantly reduced. Depending on the deployed software itself it is possible to extend the EAM system with little effort (in comparison to the promising advantages) so that external project timing planning tools are not required any more. By shifting towards an integrated planning tool, efficiency in planning an outage as well as the quality of communication of the current planning status increases. Furthermore, the basis of information for work orders by the control room staff and therefore safety can be enhanced. (orig.)

Activities of maintenance and outage

International Nuclear Information System (INIS)

Gracia-Orellan, J. M.; Gonzalez, P. L.; Verdu, M. F.; Fernandez, J. A.

2004-01-01

Iberinco Nuclear Generation Department have wanted to promote service activities in nuclear power plants for years besides its dedication to engineering activities. for it, in 1997 Nuclear Services Management was created to complement engineering activities and to be able to make an offer for products and turn key services. People involved in this Management have an extensive experience in Services Area, so that all type of maintenance works are promoted, as well other services like dismantling, fallout management and new equipment's for nuclear power plants services. Iberinco's experience in Support Services in Nuclear Power Plants allows to answer effectively to special workers during operation cycle and outages periods. These activities have been made in spanish nuclear power plants and Angra I and II plants, both of them in Brazil. In this area we provide Technical Consulting Management and Supervision to develop the following activities: - Improvement Maintenance Programs based in PSA: Implantation of Maintenance Rule in the plants. - Supervision and Assembly of design modifications in structures, systems and components. - Fulfilment of efficiency tests, inspection and turbo-group modification. - Noise and vibrations analysis. - Valves and rotative equipment calculations and diagnosis tests. Iberinco develop these outage activities itself or as contractors coordinator under its management. A lot of them have been working with Iberinco for many years and have a great experience in the Service Area they are developing. In this article, the main outage activities developed for Iberinco are detailed. (Author)

Advanced Outage and Control Center: Strategies for Nuclear Plant Outage Work Status Capabilities

Energy Technology Data Exchange (ETDEWEB)

Gregory Weatherby

2012-05-01

The research effort is a part of the Light Water Reactor Sustainability (LWRS) Program. LWRS is a research and development program sponsored by the Department of Energy, performed in close collaboration with industry to provide the technical foundations for licensing and managing the long-term, safe and economical operation of current nuclear power plants. The LWRS Program serves to help the US nuclear industry adopt new technologies and engineering solutions that facilitate the continued safe operation of the plants and extension of the current operating licenses. The Outage Control Center (OCC) Pilot Project was directed at carrying out the applied research for development and pilot of technology designed to enhance safe outage and maintenance operations, improve human performance and reliability, increase overall operational efficiency, and improve plant status control. Plant outage management is a high priority concern for the nuclear industry from cost and safety perspectives. Unfortunately, many of the underlying technologies supporting outage control are the same as those used in the 1980’s. They depend heavily upon large teams of staff, multiple work and coordination locations, and manual administrative actions that require large amounts of paper. Previous work in human reliability analysis suggests that many repetitive tasks, including paper work tasks, may have a failure rate of 1.0E-3 or higher (Gertman, 1996). With between 10,000 and 45,000 subtasks being performed during an outage (Gomes, 1996), the opportunity for human error of some consequence is a realistic concern. Although a number of factors exist that can make these errors recoverable, reducing and effectively coordinating the sheer number of tasks to be performed, particularly those that are error prone, has the potential to enhance outage efficiency and safety. Additionally, outage management requires precise coordination of work groups that do not always share similar objectives. Outage

76 FR 60938 - Advisory Committee on Reactor Safeguards (ACRS); Meeting of the ACRS Subcommittee on Power...

Science.gov (United States)

2011-09-30

... Subcommittee on Power Uprates; Notice of Meeting The ACRS Subcommittee on Power Uprates will hold a meeting on...) associated with the Nine Mile Point extended power uprate application. The [[Page 60939

Outage Risk Assessment and Management (ORAM) technology to improve outage safety and economics

International Nuclear Information System (INIS)

Kalra, S.P.

2004-01-01

The Electric Power Research Institute (EPRI) has undertaken an aggressive program, called ORAM (Outage Risk Assessment and Management), to provide utilities with tools and technology to assist in managing risk during the planning and conduct of outages. The ORAM program consists of the following 6 steps: i) Perform utility surveys and visits on shutdown risk management needs, ii) Perform probabilistic shutdown safety assessments (PSSAs) to identify generic insights that can be incorporated into risk management guidelines and identify selected areas for the development of contingency actions, iii) Develop risk management guidelines (RMG's) that provide a systematic approach to the planning and conduct of outages from a safety perspective. Incorporate insights from the shutdown safety assessments and other operating experience into the RMG's. iv) Develop selected contingency actions including a thermalhydraulic tool kit to address higher risk time periods and activities identified in the shutdown safety assessments, v) Develop computer software that integrates all of the above capability into an easy to use tool for effective shutdown operation management for utilities, vi) Provide assistance in the transfer of this technology and the application of these tools. This paper briefly describes the technical approach and tools developed under EPRI's ORAM program and its applications for improving outage safety and economics. (author)

Maintenance, outages and chemistry really can be compatible

International Nuclear Information System (INIS)

Roberts, J.G.; Deaconescu, R.

2006-01-01

'Full text:' In their address to the Canadian Nuclear Society, Bruce Power's Chemistry Design staff will describe how maintenance and outages can impact negatively on chemistry control and asset protection. Considerations of material impacts and material condition have significant influences on the approach to, and control of, chemistry. This applies equally to operation as it does during unit and/or system outages. Ideas will be presented as to how to facilitate making maintenance, outages and chemistry compatible. It will be shown how the lack of such an approach can lead to disastrous results. (author)

An Internet of Things Approach to Electrical Power Monitoring and Outage Reporting

Energy Technology Data Exchange (ETDEWEB)

Koch, Daniel B [ORNL

2017-01-01

The so-called Internet of Things concept has captured much attention recently as ordinary devices are connected to the Internet for monitoring and control purposes. One enabling technology is the proliferation of low-cost, single board computers with built-in network interfaces. Some of these are capable of hosting full-fledged operating systems that provide rich programming environments. Taken together, these features enable inexpensive solutions for even traditional tasks such as the one presented here for electrical power monitoring and outage reporting.

Outage management: A case study

International Nuclear Information System (INIS)

Haber, S.B.; Barriere, M.T.; Roberts, K.H.

1992-01-01

Outage management issues identified from a field study conducted at a two-unit commercial pressurized water reactor (PWR), when one unit was in a refueling outage and the other unit was at full power operation, are the focus of this paper. The study was conduced as part of the US Nuclear Regulatory Commission's (NRC) organizational factors research program, and therefore the issues to be addressed are from an organizational perspective. Topics discussed refer to areas identified by the NRC as critical for safety during shutdown operations, including outage planning and control, personnel stress, and improvements in training and procedures. Specifically, issues in communication, management attention, involvement and oversight, administrative processes, organizational culture, and human resources relevant to each of the areas are highlighted by example from field data collection. Insights regarding future guidance in these areas are presented based upon additional data collection subsequent to the original study

Hybrid Cascading Outage Analysis of Extreme Events with Optimized Corrective Actions

Energy Technology Data Exchange (ETDEWEB)

Vallem, Mallikarjuna R.; Vyakaranam, Bharat GNVSR; Holzer, Jesse T.; Samaan, Nader A.; Makarov, Yuri V.; Diao, Ruisheng; Huang, Qiuhua; Ke, Xinda

2017-10-19

Power system are vulnerable to extreme contingencies (like an outage of a major generating substation) that can cause significant generation and load loss and can lead to further cascading outages of other transmission facilities and generators in the system. Some cascading outages are seen within minutes following a major contingency, which may not be captured exclusively using the dynamic simulation of the power system. The utilities plan for contingencies either based on dynamic or steady state analysis separately which may not accurately capture the impact of one process on the other. We address this gap in cascading outage analysis by developing Dynamic Contingency Analysis Tool (DCAT) that can analyze hybrid dynamic and steady state behavior of the power system, including protection system models in dynamic simulations, and simulating corrective actions in post-transient steady state conditions. One of the important implemented steady state processes is to mimic operator corrective actions to mitigate aggravated states caused by dynamic cascading. This paper presents an Optimal Power Flow (OPF) based formulation for selecting corrective actions that utility operators can take during major contingency and thus automate the hybrid dynamic-steady state cascading outage process. The improved DCAT framework with OPF based corrective actions is demonstrated on IEEE 300 bus test system.

Outages planning; Planificacion de recargas

Energy Technology Data Exchange (ETDEWEB)

Blanquer, N.

2010-07-01

The reason of a nuclear power plant outage seems easy. Replace 1/3 of the total core fuel inside reactor for a new, store the old one in a pool and shuffle the rest 2/3 in other positions in the core to optimize fuel burn up. Also is needed to make the preventive, corrective and conservative maintenance, the selected design changes and the regulatory and technical requirements for equipment and systems. To make the plant outage strategy for all the above pack with nuclear safety not challenged is the objective of this article for the Spanish Nuclear Society magazine. (Author)

Balance-of-plant outage availability study. Phase I. Extension report

International Nuclear Information System (INIS)

Thomasson, F.R.

1978-09-01

After completion of the Phase 1 Refueling Outage Availability Study, Babcock and Wilcox and the U.S. Department of Energy entered into a supplemental agreement to perform a balance-of-plant maintenance, inspection, and test study with the cooperation of Duke Power Company and Arkansas Power and Light Company. The objectives were (1) to expand the Phase 1 data base, including balance-of-plant activities, to reduce outage time and increase plant availability and (2) to conduct an onsite review of plant maintenance, practices to complement the utility efforts in reducing outage time and increasing on-line operational time. Data were obtained from (1) observations during the 1977 refueling outage at Oconee 3, (2) review of maintenance practices during the Arkansas Nuclear One, Unit 1, operational cycle in 1977, and (3) selected observations of the 1978 refueling outage at ANO-1. Accumulated data were then reviewed and analyzed to produce a list of improvement recommendations for Oconee 3 and ANO-1 that can be generically applied to plants of similar design and construction

ALARA database value in future outage work planning and dose management

International Nuclear Information System (INIS)

Miller, D.W.; Green, W.H.

1995-01-01

ALARA database encompassing job-specific duration and man-rem plant specific information over three refueling outages represents an invaluable tool for the outage work planner and ALARA engineer. This paper describes dose-management trends emerging based on analysis of three refueling outages at Clinton Power Station. Conclusions reached based on hard data available from a relational database dose-tracking system is a valuable tool for planning of future outage work. The system's ability to identify key problem areas during a refueling outage is improving as more outage comparative data becomes available. Trends over a three outage period are identified in this paper in the categories of number and type of radiation work permits implemented, duration of jobs, projected vs. actual dose rates in work areas, and accuracy of outage person-rem projection. The value of the database in projecting 1 and 5 year station person-rem estimates is discussed

ALARA database value in future outage work planning and dose management

Energy Technology Data Exchange (ETDEWEB)

Miller, D.W.; Green, W.H. [Clinton Power Station Illinois Power Co., IL (United States)

1995-03-01

ALARA database encompassing job-specific duration and man-rem plant specific information over three refueling outages represents an invaluable tool for the outage work planner and ALARA engineer. This paper describes dose-management trends emerging based on analysis of three refueling outages at Clinton Power Station. Conclusions reached based on hard data available from a relational database dose-tracking system is a valuable tool for planning of future outage work. The system`s ability to identify key problem areas during a refueling outage is improving as more outage comparative data becomes available. Trends over a three outage period are identified in this paper in the categories of number and type of radiation work permits implemented, duration of jobs, projected vs. actual dose rates in work areas, and accuracy of outage person-rem projection. The value of the database in projecting 1 and 5 year station person-rem estimates is discussed.

Impacts of organization and management on outage performance

International Nuclear Information System (INIS)

Huang Yuhao; Cheng, S.-K.

2004-01-01

From probabilistic safety assessments and root cause analyses for incidents/accidents, the risk at refueling outage has recently been recognized to be comparable to (or even more significant than) the commonly evaluated risk at power in a Nuclear Power Plant (NPP). This paper summarizes the major findings in the aspect of 'organization and management', which is identified to have significant impacts on outage performance in the qualitative assessment of a PWR plant. In order to reduce the potential risk arisen from those identified imperfections, the corresponding suggestions are also proposed. (author)

Maintenance, outages and chemistry really can be compatible

Energy Technology Data Exchange (ETDEWEB)

Roberts, J.G.; Deaconescu, R. [Bruce Power, Tiverton, Ontario (Canada)

2006-07-01

'Full text:' In their address to the Canadian Nuclear Society, Bruce Power's Chemistry Design staff will describe how maintenance and outages can impact negatively on chemistry control and asset protection. Considerations of material impacts and material condition have significant influences on the approach to, and control of, chemistry. This applies equally to operation as it does during unit and/or system outages. Ideas will be presented as to how to facilitate making maintenance, outages and chemistry compatible. It will be shown how the lack of such an approach can lead to disastrous results. (author)

Development of Improved Graphical Displays for an Advanced Outage Control Center, Employing Human Factors Principles for Outage Schedule Management

Energy Technology Data Exchange (ETDEWEB)

St Germain, Shawn Walter [Idaho National Lab. (INL), Idaho Falls, ID (United States); Farris, Ronald Keith [Idaho National Lab. (INL), Idaho Falls, ID (United States); Thomas, Kenneth David [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2015-09-01

The long-term viability of existing nuclear power plants in the United States (U.S.) is dependent upon a number of factors, including maintaining high capacity factors, maintaining nuclear safety, and reducing operating costs, particularly those associated with refueling outages. Refueling outages typically take 20-30 days, and for existing light water NPPs in the U.S., the reactor cannot be in operation during the outage. Furthermore, given that many NPPs generate between $1-1.5 million/day in revenue when in operation, there is considerable interest in shortening the length of refueling outages. Yet refueling outages are highly complex operations, involving multiple concurrent and dependent activities that are somewhat challenging to coordinate; therefore, finding ways to improve refueling outage performance, while maintaining nuclear safety has proven to be difficult. The Advanced Outage Control Center (AOCC) project is a research and development (R&D) demonstration activity under the LWRS Program. LWRS is an R&D program that works closely with industry R&D programs to establish technical foundations for the licensing and managing of long-term, safe, and economical operation of current fleet of NPPs. As such, the LWRS Advanced Outage Control Center project has the goal of improving the management of commercial NPP refueling outages. To accomplish this goal, INL is developing an advanced outage control center (OCC) that is specifically designed to maximize the usefulness of communication and collaboration technologies for outage coordination and problem resolution activities. The overall focus is on developing an AOCC with the following capabilities that enables plant and OCC staff to; Collaborate in real-time to address emergent issues; Effectively communicate outage status to all workers involved in the outage; Effectively communicate discovered conditions in the field to the OCC; Provide real-time work status; Provide automatic pending support notifications

Development of Improved Graphical Displays for an Advanced Outage Control Center, Employing Human Factors Principles for Outage Schedule Management

International Nuclear Information System (INIS)

St Germain, Shawn Walter; Farris, Ronald Keith; Thomas, Kenneth David

2015-01-01

The long-term viability of existing nuclear power plants in the United States (U.S.) is dependent upon a number of factors, including maintaining high capacity factors, maintaining nuclear safety, and reducing operating costs, particularly those associated with refueling outages. Refueling outages typically take 20-30 days, and for existing light water NPPs in the U.S., the reactor cannot be in operation during the outage. Furthermore, given that many NPPs generate between $1-1.5 million/day in revenue when in operation, there is considerable interest in shortening the length of refueling outages. Yet refueling outages are highly complex operations, involving multiple concurrent and dependent activities that are somewhat challenging to coordinate; therefore, finding ways to improve refueling outage performance, while maintaining nuclear safety has proven to be difficult. The Advanced Outage Control Center (AOCC) project is a research and development (R&D) demonstration activity under the LWRS Program. LWRS is an R&D program that works closely with industry R&D programs to establish technical foundations for the licensing and managing of long-term, safe, and economical operation of current fleet of NPPs. As such, the LWRS Advanced Outage Control Center project has the goal of improving the management of commercial NPP refueling outages. To accomplish this goal, INL is developing an advanced outage control center (OCC) that is specifically designed to maximize the usefulness of communication and collaboration technologies for outage coordination and problem resolution activities. The overall focus is on developing an AOCC with the following capabilities that enables plant and OCC staff to; Collaborate in real-time to address emergent issues; Effectively communicate outage status to all workers involved in the outage; Effectively communicate discovered conditions in the field to the OCC; Provide real-time work status; Provide automatic pending support notifications

Extended layup of steam generators during a refurbishment outage

International Nuclear Information System (INIS)

Marks, C.R.; Little, M.D.; Slade, J.; Gendron, T.

2009-01-01

In May 2008, Point Lepreau Generating Station (PLGS), owned and operated by New Brunswick Power Nuclear (NBPN), entered an extended refurbishment outage initially expected to last approximately 18 months. NBPN had the two inter-related goals with respect to layup of the steam generators during this period: equipment preservation and inspection interval modification. The steam generators were to be preserved such that there was no loss of operating life due to corrosion of either the tubing (Alloy 800NG) or other internal components (with carbon steel being the limiting material with respect to corrosion). Additionally, NBPN desired that the time in layup not count as operating time in setting the schedule for future inspections. That is, a key goal of the steam generator layup is that the future inspection interval be based on operating time, not calendar time. The NBPN approach consists of the following four steps: A review of industry operating experience with long outages (including both PWRs and PHWRs); The development of technically based layup strategies and procedures; A mid-outage review of the implementation of the layup strategies and procedures; and A post-outage review to determine if the actual conditions in the steam generators will support modification of the inspection interval. This paper discusses the results of the first three of these steps. At this time, the plant is still in the refurbishment outage. Throughout the outage evaluation process, the following issues have been the main focus of the reviews: The potential for degradation (pitting and cracking) of steam generator tubes; The potential for general corrosion of carbon and low alloy steel internals; Oxidation of deposits (which could subsequently lead to oxidizing conditions during operation, possibly leading to tube degradation). This paper discusses the industry operating experience reviewed, the pre-outage assessments, and the mid-outage assessments. Current outage planning places the

Outage management

International Nuclear Information System (INIS)

Anonymous

2006-01-01

Since constructing Japan's first PWR plant, Mihama Unit 1, MHI has been working to upgrade its technologies. The ongoing goal is to provide PWR nuclear power plants with levels of reliability, safety, economy operation and maintainability unparalleled in the world market. To fulfill its obligations and responsibility as an integrated plant manufacturer in the nuclear industry, MHI keeps a close eye on every facility, component, device and sub-component from the viewpoint of its customers. Backed by its rich experience and advanced technology, MHI continues to enhance the safety, reliability and economy of nuclear plants introducing improvements at every level. MHI continues to develop and improve diagnostic and inspection technologies based on its more than 30 years of experience in inspection and servicing the major and auxiliary facilities within nuclear power plants. MHI secures the integrity of components by developing and deploying technologies to minimize the wear of components and to repair and replace parts either degraded by age or unduly susceptible to wear. MHI backs its development of these technologies with its comprehensive technical capabilities in the design of remote operation equipment and electro mechanics as well as its expertise in basic technologies such as welding and machining. Mitsubishi Heavy Industries, Ltd. is not only a PWR plant constructor, but also offers complete outage support and component services. In partnership with our customers, MHI is helping to reduce outage duration, radiation exposure and costs, by providing its state of the art engineering knowledge, advanced non-destructive examination, inspection, maintenance and repair technologies mentioned above. MHI is performing large equipment refurbishment such as Steam Generator Replacement, Reactor Vessel Head Replacement, LP/HP turbine replacement, and recently completed the first Core Internal Replacement in the world. The following activities are part of the outage

Balance-of-plant outage availability study. Phase I. Extension report. [PWR

Energy Technology Data Exchange (ETDEWEB)

Thomasson, F.R.

1978-09-01

After completion of the Phase 1 Refueling Outage Availability Study, Babcock and Wilcox and the U.S. Department of Energy entered into a supplemental agreement to perform a balance-of-plant maintenance, inspection, and test study with the cooperation of Duke Power Company and Arkansas Power and Light Company. The objectives were (1) to expand the Phase 1 data base, including balance-of-plant activities, to reduce outage time and increase plant availability and (2) to conduct an onsite review of plant maintenance, practices to complement the utility efforts in reducing outage time and increasing on-line operational time. Data were obtained from (1) observations during the 1977 refueling outage at Oconee 3, (2) review of maintenance practices during the Arkansas Nuclear One, Unit 1, operational cycle in 1977, and (3) selected observations of the 1978 refueling outage at ANO-1. Accumulated data were then reviewed and analyzed to produce a list of improvement recommendations for Oconee 3 and ANO-1 that can be generically applied to plants of similar design and construction.

Evolution of an outage management organization in a small utility

International Nuclear Information System (INIS)

Oubre, R.P.; Shetler, J.

1985-01-01

Six refueling outages with a number of major equipment failure outages have taught Rancho Seco management three main items. One is that a dedicated management organization must be formed for the purpose of controlling work functions at Rancho Seco. This dedicated organization must have the experience of the plant and not have the responsibility for the actual maintenance. Second, upper management within a power plant must get directly involved in the outage. Upper management must show their presence, give input, and be available when needed. The third item learned is that the scheduling organization must be adequately staffed. Although Rancho Seco completed a refueling outage in 1978 within only 36 days, additional inspection requirements due to regulatory changes and/or previous equipment failures requiring follow-up actions would place the shortest possible outage today at approx.70 days. The only way an organization can keep this outage time down is with the proper scheduling of the resources and the timely coordination of activities to reduce conflicts

Piping hydrodynamic loads for a PWR power up-rate with steam generator replacement

International Nuclear Information System (INIS)

Julie M Jarvis; Allen T Vieira; James M Gilmer

2005-01-01

Full text of publication follows: Pipe break hydrodynamic loads are calculated for various systems in a PWR for a Power Up-rate (PUR) with a Steam Generator Replacement (SGR). PUR with SGR can change the system pressures, mass flowrates and pipe routing/configuration. These changes can alter the steam generator piping steam/water hammer loads. This paper discusses the need to benchmark against the original design basis, the use of different modeling techniques, and lessons learned. Benchmarking for licensing in the United States is vital in consideration of 10CFR50.59 and other licensing and safety issues. RELAP5 and its force post-processor R5FORCE are used to model the transient loads for various piping systems such as main feedwater and blowdown systems. Other modeling applications, including the Bechtel GAFT program, are used to evaluate loadings in the main steam piping. Forces are calculated for main steam turbine stop valve closure, feedwater pipe breaks and subsequent check valve slam, and blowdown isolation valve closure. These PUR/SGR forces are compared with the original design basis forces. Modeling techniques discussed include proper valve closure modeling, sonic velocity changes due to pipe material changes, and two phase flow effects. Lessons learned based on analyses done for several PWR PUR with SGR are presented. Lessons learned from these analyses include choosing the optimal replacement piping size and routing to improve system performance without resulting in excessive piping loads. (authors)

76 FR 7883 - Advisory Committee on Reactor Safeguards (ACRS); Meeting of the ACRS Subcommittee on Power...

Science.gov (United States)

2011-02-11

... Subcommittee on Power Uprates; Notice of Meeting The ACRS Subcommittee on Power Uprates will hold a meeting on... will review the staff's evaluation of the Point Beach Units 1 and 2 Extended Power Uprate application... can be made. Thirty five hard copies of each presentation or handout should be provided to the...

Coupled RELAP5/PANTHER/COBRA steam line break accident analysis in support of licensing DOEL 2 power uprate and steam generator replacement

International Nuclear Information System (INIS)

Zhang, J.; Bosso, S.; Henno, X.; Ouliddren, K.; Schneidesch, C.R.; Hove, W. van

2004-01-01

The nuclear reactor accident analyses using best estimate codes provide a better understanding and more accurate modeling of the key physical phenomena, which allows a more realistic evaluation of the conservatism and margins in the final safety analysis report (FSAR) accident analysis. The use of the best estimate codes and methods is necessary to meet the increasing technical, licensing and regulatory requirements for major plant changes (e.g. steam generator replacement), power uprate, core design optimization (cycle extension), as well as Periodic Safety Review. Since 1992, Tractebel Engineering (TE) has developed and applied a deterministic bounding approach to FASR accident analysis using the best estimate system thermal hydraulic code RELAP5/MOD2.5 and the subchannel thermal hydraulic code COBRA-3C. This approach has been accepted by the Belgian Safety Authorities, and turned out to be cost effective for most of the non-LOCA transient analyses. Since this approach adapts a decoupled modeling of the core responses, the analysis results often involved too large un-quantified conservatisms, due to either simplistic approximations for asymmetric accidents with strong 3D core neutronics - plant thermal hydraulics interactions, or additional penalties introduced from 'incoherent' initial/boundary conditions for separate plant and core analyses. Therefore, an external dynamic coupling between the RELAP5/MOD2.5 code and the 3-D neutronic code PANTHER was implemented since 1997 via the transient analysis code linkage program TALINK. Furthermore, a static linkage between the PANTHER code and the COBRA-3C code was developed for on-line calculation of (Departure from Nucleate Boiling Ratio (DNBR). TE intends to use the coupled code package for licensing non-symmetric FSAR accident analysis. The TE coupled code package has been applied to develop a main steam line break (MSLB) accident analysis methodology [using the TE deterministic bounding approach. The methodology

Outage performance of cognitive radio systems with Improper Gaussian signaling

KAUST Repository

Amin, Osama

2015-06-14

Improper Gaussian signaling has proved its ability to improve the achievable rate of the systems that suffer from interference compared with proper Gaussian signaling. In this paper, we first study impact of improper Gaussian signaling on the performance of the cognitive radio system by analyzing the outage probability of both the primary user (PU) and the secondary user (SU). We derive exact expression of the SU outage probability and upper and lower bounds for the PU outage probability. Then, we design the SU signal by adjusting its transmitted power and the circularity coefficient to minimize the SU outage probability while maintaining a certain PU quality-of-service. Finally, we evaluate the proposed bounds and adaptive algorithms by numerical results.

Uprated OMS Engine Status-Sea Level Testing Results

Science.gov (United States)

Bertolino, J. D.; Boyd, W. C.

1990-01-01

The current Space Shuttle Orbital Maneuvering Engine (OME) is pressure fed, utilizing storable propellants. Performance uprating of this engine, through the use of a gas generator driven turbopump to increase operating pressure, is being pursued by the NASA Johnson Space Center (JSC). Component level design, fabrication, and test activities for this engine system have been on-going since 1984. More recently, a complete engine designated the Integrated Component Test Bed (ICTB), was tested at sea level conditions by Aerojet. A description of the test hardware and results of the sea level test program are presented. These results, which include the test condition operating envelope and projected performance at altitude conditions, confirm the capability of the selected Uprated OME (UOME) configuration to meet or exceed performance and operational requirements. Engine flexibility, demonstrated through testing at two different operational mixture ratios, along with a summary of projected Space Shuttle performance enhancements using the UOME, are discussed. Planned future activities, including ICTB tests at simulated altitude conditions, and recommendations for further engine development, are also discussed.

Development of an Agent Based Model to Estimate and Reduce Time to Restoration of Storm Induced Power Outages

Science.gov (United States)

Walsh, T.; Layton, T.; Mellor, J. E.

2017-12-01

Storm damage to the electric grid impacts 23 million electric utility customers and costs US consumers $119 billion annually. Current restoration techniques rely on the past experiences of emergency managers. There are few analytical simulation and prediction tools available for utility managers to optimize storm recovery and decrease consumer cost, lost revenue and restoration time. We developed an agent based model (ABM) for storm recovery in Connecticut. An ABM is a computer modeling technique comprised of agents who are given certain behavioral rules and operate in a given environment. It allows the user to simulate complex systems by varying user-defined parameters to study emergent, unpredicted behavior. The ABM incorporates the road network and electric utility grid for the state, is validated using actual storm event recoveries and utilizes the Dijkstra routing algorithm to determine the best path for repair crews to travel between outages. The ABM has benefits for both researchers and utility managers. It can simulate complex system dynamics, rank variable importance, find tipping points that could significantly reduce restoration time or costs and test a broad range of scenarios. It is a modular, scalable and adaptable technique that can simulate scenarios in silico to inform emergency managers before and during storm events to optimize restoration strategies and better manage expectations of when power will be restored. Results indicate that total restoration time is strongly dependent on the number of crews. However, there is a threshold whereby more crews will not decrease the restoration time, which depends on the total number of outages. The addition of outside crews is more beneficial for storms with a higher number of outages. The time to restoration increases linearly with increasing repair time, while the travel speed has little overall effect on total restoration time. Crews traveling to the nearest outage reduces the total restoration time

Cycle 7 outage experience

International Nuclear Information System (INIS)

Gadeken, A.D.

1986-03-01

The scheduled 58-day refueling outage in preparation for the seventh operating cycle of the Fast Flux Test Facility (FFTF) was successfully completed three days ahead of schedule. The planning and execution of the outage was greatly aided by Project/2 automated scheduling capabilities. For example, the use of ''maintenance windows'' and resource loading capabilities was particularly effective. The value of the planning process was demonstrated by the smooth transition into the outage phase after an early shutdown and set the stage for our best outage to date

Consequences of long-term power outages and high electricity prices lasting for months

International Nuclear Information System (INIS)

2005-01-01

Several areas in the world have experienced electricity outages for longer periods of time, but the consequences of these are sparsely documented. There is a need for further analysis of the socioeconomic consequences of the outages. In addition to KILE (Quality adjusted revenue framework for un supplied energy) costs one has to take into account that the costs often increase proportionally with the durance of the outage, and that KILE tariffs do not reflect lost consumer's surplus for products that are not produced during an outage. A good example is the public underground transport, where the company's economical loss can be significantly smaller than the loss of utility value for the travellers. If the authorities act with reasonability it is difficult to see that periods with very high prices represent a big problem. The most important problems are related to diffused effects, especially for households with a weak economy. These problems can be solved with improved contractual forms (price guarantees) or by transfers to the households, without weakening the incentives for electricity economising (ml)

Summary of operating experience in Swiss nuclear power plants 1993

International Nuclear Information System (INIS)

1994-07-01

In 1993 the Swiss nuclear power plants produced their third highest combined annual output. The contribution to the total electricity generation in the country was close to 37%. Replacement of the steam generators in Beznau Unit 1 resulted in a longer than usual annual outage. For the other four units the availability figures were close to, or exceeded, those of previous years. The energy utilization was, however, lowered due to load reduction in autumn resulting from unusually high production by the hydro-electric power plants. The steam generator replacement at Beznau enabled an increase in electrical power of about 2% without increase in reactor power. With the approval of the Swiss government in December 1992, the output of the Muehleberg power plant was increased in two stages by a total of 10%. The application for an unlimited operating license for Beznau Unit 2, and for a power uprate at the Leibstadt power plant, are still pending. The average number of scrams at the Swiss plants remained stable, at less than one scram per reactor year. As a result of experience in the Swedish nuclear power plant at Barsebaeck, the suction strainers of the emergency core cooling systems of the boiling water reactors at Muehleberg and Leibstadt were replaced by strainers with larger surface areas. The re-inspection of crack indications previously detected in the core shroud of the Muehleberg reactor and the penetration tubes in the reactor pressure vessel closure head of Beznau revealed no growth during the intervening operating periods. Following the completion of installation activities during the annual outages at Beznau Unit 1, Goesgen and Leibstadt, all Swiss nuclear power plants are now equipped with filtered containment venting systems. (author) figs., tabs

Darlington Station outage - a maintenance perspective

International Nuclear Information System (INIS)

Plourde, J.; Marczak, J.; Stone, M.; Myers, R.; Sutton, K.

1997-01-01

Ontario Hydro's Darlington Nuclear Generating Station (4x881MW(e)net) has carried out its first station outage since full commercial operation. The outage presented challenges to the organization in terms of outage planning, support, management, and safe execution within the constraints of schedule, budget and resources. This paper will focus on the success of the outage maintenance program, identifying the major work programs - a vacuum structure and containment outage, an emergency service water system outage, an emergency coolant injection system outage, intake channel inspections, low pressure service water inspections, and significant outage maintenance work on each of the four reactor units. Planning for the outage was initiated early in anticipation of this important milestone in the station's life. Detailed safety reviews - nuclear, radiation, and conventional - were conducted in support of the planned maintenance program. System lineup and work protection were provided by the Station Operator work group. Work protection permitry was initiated well in advance of the outage. Station maintenance staff resources were bolstered in support of the outage to ensure program execution could be maintained within the schedule. Training programs were in place to ensure that expectations were clear and that high standards would be maintained. Materials management issues in support of maintenance activities were given high priority to ensure no delays to the planned work. Station management review and monitoring in preparation for and during the outage ensured that staff priorities remained focused. Lessons learned from the outage execution are being formalized in maintenance procedures and outage management procedures, and shared with the nuclear community. (author)

Underlay Cognitive Radio Systems with Improper Gaussian Signaling: Outage Performance Analysis

KAUST Repository

Amin, Osama

2016-03-29

Improper Gaussian signaling has the ability over proper (conventional) Gaussian signaling to improve the achievable rate of systems that suffer from interference. In this paper, we study the impact of using improper Gaussian signaling on the performance limits of the underlay cognitive radio system by analyzing the achievable outage probability of both the primary user (PU) and secondary user (SU). We derive the exact outage probability expression of the SU and construct upper and lower bounds of the PU outage probability which results in formulating an approximate expression of the PU outage probability. This allows us to design the SU signal by adjusting its transmitted power and the circularity coefficient to minimize the SU outage probability while maintaining a certain PU quality-of-service. Finally, we evaluate the derived expressions for both the SU and the PU and the corresponding adaptive algorithms by numerical results.

Underlay Cognitive Radio Systems with Improper Gaussian Signaling: Outage Performance Analysis

KAUST Repository

Amin, Osama; Abediseid, Walid; Alouini, Mohamed-Slim

2016-01-01

Improper Gaussian signaling has the ability over proper (conventional) Gaussian signaling to improve the achievable rate of systems that suffer from interference. In this paper, we study the impact of using improper Gaussian signaling on the performance limits of the underlay cognitive radio system by analyzing the achievable outage probability of both the primary user (PU) and secondary user (SU). We derive the exact outage probability expression of the SU and construct upper and lower bounds of the PU outage probability which results in formulating an approximate expression of the PU outage probability. This allows us to design the SU signal by adjusting its transmitted power and the circularity coefficient to minimize the SU outage probability while maintaining a certain PU quality-of-service. Finally, we evaluate the derived expressions for both the SU and the PU and the corresponding adaptive algorithms by numerical results.

Outage planning in Japan

International Nuclear Information System (INIS)

Nedderman, John.

1997-01-01

Nuclear plant operators in Japan are constrained to keep refuelling and maintenance outages to a minimum by the regulation limiting operating cycles to no longer than 13 months. Outage planning by two contrasting operators is described. Hokkaido Electric, which operates only one plant, Tomari, with two PWRs, plans to reduce outage time from the present 65 days in two stages. Detailed review of previous outage schedules has shown that a reduction to 59 days should be achievable by careful planning without any fundamental changes. The second reduction to 49 days will require such measures as relaxing water purity standards, rescheduling fuel unloading and loading shifts and speeding up eddy current testing of primary equipment by using steam generator nozzle dams. Kansai Electric, operating 11 PWRs at three plants, has scope for reducing outages at all of its units using a range of measures. Steam generator replacement in the seven oldest reactors, completed in July 1997, is by far the most significant of these and is expected to save 64 days repair time in a previous average outage time of 131 days. (UK)

Line outage contingency analysis including the system islanding scenario

Energy Technology Data Exchange (ETDEWEB)

Hazarika, D.; Bhuyan, S. [Assam Engineering College, Jalukbari, Guwahati 781013 (India); Chowdhury, S.P. [Jadavpur University, Jadavpur, Kolkata 700 032 (India)

2006-05-15

The paper describes an algorithm for determining the line outage contingency of a line taking into account of line over load effect in remaining lines and subsequent tripping of over loaded line(s) leading to possible system split or islanding of a power system. The optimally ordered sparse [B'], [B'] matrices for the integrated system are used for load flow analysis to determine modified values of voltage phase angles [{delta}] and bus voltages [V] to determine the over loading effect on the remaining lines due to outage of a selected line outage contingency. In case of over loading in remaining line(s), the over loaded lines are removed from the system and a topology processor is used to find the islands. A fast decoupled load flow (FDLF) analysis is carried out for finding out the system variables for the islanded (or single island) system by incorporating appropriate modification in the [B'] and [B'] matrices of the integrated system. Line outage indices based on line overload, loss of load, loss of generation and static voltage stability are computed to indicate severity of a line outage of a selected line. (author)

A framework and review of customer outage costs: Integration and analysis of electric utility outage cost surveys

Energy Technology Data Exchange (ETDEWEB)

Lawton, Leora; Sullivan, Michael; Van Liere, Kent; Katz, Aaron; Eto, Joseph

2003-11-01

A clear understanding of the monetary value that customers place on reliability and the factors that give rise to higher and lower values is an essential tool in determining investment in the grid. The recent National Transmission Grid Study recognizes the need for this information as one of growing importance for both public and private decision makers. In response, the U.S. Department of Energy has undertaken this study, as a first step toward addressing the current absence of consistent data needed to support better estimates of the economic value of electricity reliability. Twenty-four studies, conducted by eight electric utilities between 1989 and 2002 representing residential and commercial/industrial (small, medium and large) customer groups, were chosen for analysis. The studies cover virtually all of the Southeast, most of the western United States, including California, rural Washington and Oregon, and the Midwest south and east of Chicago. All variables were standardized to a consistent metric and dollar amounts were adjusted to the 2002 CPI. The data were then incorporated into a meta-database in which each outage scenario (e.g., the lost of electric service for one hour on a weekday summer afternoon) is treated as an independent case or record both to permit comparisons between outage characteristics and to increase the statistical power of analysis results. Unadjusted average outage costs and Tobit models that estimate customer damage functions are presented. The customer damage functions express customer outage costs for a given outage scenario and customer class as a function of location, time of day, consumption, and business type. One can use the damage functions to calculate outage costs for specific customer types. For example, using the customer damage functions, the cost experienced by an ''average'' customer resulting from a 1 hour summer afternoon outage is estimated to be approximately $3 for a residential customer, $1

Outages 1999 and 2000, investments in safety and long-term operation of NE Krsko

International Nuclear Information System (INIS)

Sirola, P.; Krajnc, J.; Androjna, F.

1999-01-01

Plant outage is an important part of nuclear power plant operation. During that time the conditions are established for the performance of specific activities, such as refueling, tests, inspections, preventive and corrective maintenance and modifications, that are intended to confirm proper condition and availability of safety and other important components and improve overall plant safety and reliability. It is well know that in Nuclear Power Plant Krsko (Nuklearna elektrarna Krsko NEK) during Outage 2000 new Steam Generators (SGs) will be placed in service, while Outage '99 was used for preparatory works. But the importance of those two outages is even greater, because they are implementing a broad number of improvements and establishing a basis for long-term plant operation. Outage '99 required very detailed planning to assure a good control over the outage activities and operational plant systems necessary for safe shutdown. Numerous activities took place in a relatively narrow space in the Reactor Building. Some of these activities will have a big significance for the future. The article treats the status update and summarizes the specifics and importance of the mentioned activities to long-term plant safe and reliable operation.(author)

Enhanced outage prediction modeling for strong extratropical storms and hurricanes in the Northeastern United States

Science.gov (United States)

Cerrai, D.; Anagnostou, E. N.; Wanik, D. W.; Bhuiyan, M. A. E.; Zhang, X.; Yang, J.; Astitha, M.; Frediani, M. E.; Schwartz, C. S.; Pardakhti, M.

2016-12-01

The overwhelming majority of human activities need reliable electric power. Severe weather events can cause power outages, resulting in substantial economic losses and a temporary worsening of living conditions. Accurate prediction of these events and the communication of forecasted impacts to the affected utilities is necessary for efficient emergency preparedness and mitigation. The University of Connecticut Outage Prediction Model (OPM) uses regression tree models, high-resolution weather reanalysis and real-time weather forecasts (WRF and NCAR ensemble), airport station data, vegetation and electric grid characteristics and historical outage data to forecast the number and spatial distribution of outages in the power distribution grid located within dense vegetation. Recent OPM improvements consist of improved storm classification and addition of new predictive weather-related variables and are demonstrated using a leave-one-storm-out cross-validation based on 130 severe extratropical storms and two hurricanes (Sandy and Irene) in the Northeast US. We show that it is possible to predict the number of trouble spots causing outages in the electric grid with a median absolute percentage error as low as 27% for some storm types, and at most around 40%, in a scale that varies between four orders of magnitude, from few outages to tens of thousands. This outage information can be communicated to the electric utility to manage allocation of crews and equipment and minimize the recovery time for an upcoming storm hazard.

Key issues for the control of refueling outage duration and costs in PWR nuclear power plants

International Nuclear Information System (INIS)

Degrave, C.; Martin-Onraet, M.

2000-01-01

For several years, EDF, within the framework of the CIDEM project and in collaboration with some German Utilities, has undertaken a detailed review of the operating experience both of its own NPP and of foreign units, in order to improve the performances of future units under design, particularly the French-German European Pressurized Reactor (EPR) project. This review made it possible to identify the key issues allowing to decrease the duration of refueling and maintenance outages. These key issues can be classified in 3 categories: Design; Maintenance and Logistic Support; Outage Management. Most key issues in the design field and some in the logistic support field have been studied and could be integrated into the design of any future PWR unit, as for the EPR project. Some of them could also be adapted to current plants, provided they are feasible and profitable. The organization must be tailored to each country, utility or period: it widely depends on the power production environment, particularly in a deregulation context. (author)

Does Your Domestic Photovoltaic Energy System Survive Grid Outages?

Directory of Open Access Journals (Sweden)

Marijn R. Jongerden

2016-09-01

Full Text Available Domestic renewable energy systems, including photovoltaic energy generation, as well as local storage, are becoming increasingly popular and economically feasible, but do come with a wide range of options. Hence, it can be difficult to match their specification to specific customer’s needs. Next to the usage-specific demand profiles and location-specific production profiles, local energy storage through the use of batteries is becoming increasingly important, since it allows one to balance variations in production and demand, either locally or via the grid. Moreover, local storage can also help to ensure a continuous energy supply in the presence of grid outages, at least for a while. Hybrid Petri net (HPN models allow one to analyze the effect of different battery management strategies on the continuity of such energy systems in the case of grid outages. The current paper focuses on one of these strategies, the so-called smart strategy, that reserves a certain percentage of the battery capacity to be only used in case of grid outages. Additionally, we introduce a new strategy that makes better use of the reserved backup capacity, by reducing the demand in the presence of a grid outage through a prioritization mechanism. This new strategy, called power-save, only allows the essential (high-priority demand to draw from the battery during power outages. We show that this new strategy outperforms previously-proposed strategies through a careful analysis of a number of scenarios and for a selection of survivability measures, such as minimum survivability per day, number of survivable hours per day, minimum survivability per year and various survivability quantiles.

Study of Arkansas Nuclear One-1 13th refueling outage

International Nuclear Information System (INIS)

Hashiba, Takashi

1997-01-01

Recently performance of nuclear power plants in the USA has improved remarkably. Their average automatic shutdown rate has been sharply dropping, although it is still higher than that in Japan, and their average capacity factor has become higher than that in Japan in recent years. One of the main contributors is an extension of the operational period, and another is a shortening of refueling-outage time. It is considerably difficult to have accomplished both the improvement of plant reliability and shortening of refueling-outage time because their refueling outage corresponds to our periodical inspection which is central to maintenance activities in Japanese plants. In order to learn how they have been achieved, a visit to Arkansas Nuclear One-1 (ANO-1) which obtained the top-class result of SALP (Systematic Assessment of Licensee Performance) performed by the Nuclear Regulatory Commission was planned and study of their 13th refueling outage was carried out. Their achievements result from performance-base maintenance and on-line maintenance, based on a proper preventive maintenance program, and untiring efforts of efficiency improvement, represented by the introduction of several on-line systems. And the reason behind this is severe competition concerning power generation cost reduction. (author)

Study of Arkansas Nuclear One-1 13th refueling outage

Energy Technology Data Exchange (ETDEWEB)

Hashiba, Takashi [Institute of Nuclear Safety System Inc., Seika, Kyoto (Japan)

1997-09-01

Recently performance of nuclear power plants in the USA has improved remarkably. Their average automatic shutdown rate has been sharply dropping, although it is still higher than that in Japan, and their average capacity factor has become higher than that in Japan in recent years. One of the main contributors is an extension of the operational period, and another is a shortening of refueling-outage time. It is considerably difficult to have accomplished both the improvement of plant reliability and shortening of refueling-outage time because their refueling outage corresponds to our periodical inspection which is central to maintenance activities in Japanese plants. In order to learn how they have been achieved, a visit to Arkansas Nuclear One-1 (ANO-1) which obtained the top-class result of SALP (Systematic Assessment of Licensee Performance) performed by the Nuclear Regulatory Commission was planned and study of their 13th refueling outage was carried out. Their achievements result from performance-base maintenance and on-line maintenance, based on a proper preventive maintenance program, and untiring efforts of efficiency improvement, represented by the introduction of several on-line systems. And the reason behind this is severe competition concerning power generation cost reduction. (author)

Outage Analysis of Spectrum-Sharing over M-Block Fading with Sensing Information

KAUST Repository

Alabbasi, Abdulrahman

2016-07-13

Future wireless technologies, such as, 5G, are expected to support real-time applications with high data throughput, e.g., holographic meetings. From a bandwidth perspective, cognitive radio is a promising technology to enhance the system’s throughput via sharing the licensed spectrum. From a delay perspective, it is well known that increasing the number of decoding blocks will improve the system robustness against errors, while increasing the delay. Therefore, optimally allocating the resources to determine the tradeoff of tuning the length of decoding blocks while sharing the spectrum is a critical challenge for future wireless systems. In this work, we minimize the targeted outage probability over the block-fading channels while utilizing the spectrum-sharing concept. The secondary user’s outage region and the corresponding optimal power are derived, over twoblocks and M-blocks fading channels. We propose two suboptimal power strategies and derive the associated asymptotic lower and upper bounds on the outage probability with tractable expressions. These bounds allow us to derive the exact diversity order of the secondary user’s outage probability. To further enhance the system’s performance, we also investigate the impact of including the sensing information on the outage problem. The outage problem is then solved via proposing an alternating optimization algorithm, which utilizes the verified strict quasiconvex structure of the problem. Selected numerical results are presented to characterize the system’s behavior and show the improvements of several sharing concepts.

Understanding the Benefits of Dispersed Grid-Connected Photovoltaics: From Avoiding the Next Major Outage to Taming Wholesale Power Markets

International Nuclear Information System (INIS)

Letendre, Steven E.; Perez, Richard

2006-01-01

Thanks to new solar resource assessment techniques using cloud cover data available from geostationary satellites, it is apparent that grid-connected PV installations can serve to enhance electric grid reliability, preventing or hastening recovery from major power outages and serving to mitigate extreme price spikes in wholesale energy markets. (author)

Commercial operation and outage experience of ABWR at Kashiwazaki-Kariwa units Nos. 6 and 7

International Nuclear Information System (INIS)

Anahara, N.; Yamada, M.; Kataoka, H.

2000-01-01

Kashiwazaki-Kariwa Nuclear Power Station Units Nos. 6 and 7, the world's first ABWRs (Advanced Boiling Water Reactor), started commercial operation on November 7, 1996 and July 2, 1997, respectively, and continued their commercial operation with a high capacity factor, low occupational radiation exposure and radioactive waste. Units 6 and 7 were in their 3rd cycle operation until 25th April 1999 and 1st November 1999, respectively. Thermal efficiency was 35.4-35.8% (design thermal efficiency: 34.5%) during these period, demonstrating better performance than that of BWR-5 (design thermal efficiency: 33.4%). Nos. 6 and 7 have experienced 2 annual outages. The first outage of unit No. 6 started on November 20, 1997 and was completed within 61 days (including 6 New Year holidays), and the second outage started on March 13, 1999 and was completed within 44 days. The first annual outage of unit No. 7 started on May 27, 1998, earlier than it would normally have been, to avoid an annual outage during the summer, and was completed within 55 days, and the second outage started on September 18th, 1999 and was completed within 45 days, All annual outages were carried out within a very short time period without any severe malfunctions, including newly designed ABWR systems and equipment. As the first outage in Japan, 55 days is a very short period, despite the fact that the Nos. 6 and 7 are the first ABWRs in the world and the largest capacity units in Japan. The total occupational radiation exposure of No. 6 was 300 man-mSv (1st outage) and 331 man-mSv (2nd outage). That of Unit 7 was 153 man-mSv (1st outage) Those of unit No. 6 were at the same level as those of unit No. 3, which is the latest design 1100MW(e) BWR-5. That of unit No. 7 was the lowest ever at Kashiwazaki-Kariwa nuclear power station. The drums of radioactive waste discharged during the annual outage numbered 54 (1st outage) for No. 6 and 62 (1st outage) for No. 7, which was less than the design target of 100

Outage optimization - the US experience and approach

International Nuclear Information System (INIS)

LaPlatney, J.

2007-01-01

Sustainable development of Nuclear Energy depends heavily on excellent performance of the existing fleet which in turn depends heavily on the performance of planned outages. Some reactor fleets, for example Finland and Germany, have demonstrated sustained good outage performance from their start of commercial operation. Others, such as the US, have improved performance over time. The principles behind a successful outage optimization process are: -) duration is not sole measure of outage success, -) outage work must be performed safely, -) scope selection must focus on improving plant material condition to improve reliability, -) all approved outage work must be completed, -) work must be done cost effectively, -) post-outage plant reliability is a key measure of outage success, and -) outage lessons learned must be effectively implemented to achieve continuous improvement. This approach has proven its superiority over simple outage shortening, and has yielded good results in the US fleet over the past 15 years

Outage management philosophies at Oconee nuclear station

International Nuclear Information System (INIS)

Bond, R.T.

1991-01-01

At Oconee the biggest single factor in improving availability and cutting cost per kilowatt-hour is reducing outage lengths. This must be accomplished without compromising the quality of the work that must be performed during these outages. Oconee has completed 35 refueling outages and has gained considerable experience in outage management. Since 1984, outage costs and durations have consistently been reduced while continuing to improve capacity factors. The last 6 refueling outages were 43, 42, 45, 42, 41, and 44 days, respectively. The capacity factors for these units between refueling outages are 98, 94, 96, 98, and 98%, respectively. The average cost of outages has been less than $12 million. It is believed that success cannot be attributed to any one factor by itself but is a compilation of many factors, all complementing each other. It is also believed, however, that there are four key areas that represent philosophies and can be given most of the credit for successful outages: planning, experience, teamwork, and outage management

Management techniques that keep outages on schedule

International Nuclear Information System (INIS)

Taylor, R.B.

1987-01-01

During the immature operation of the Pickering Units 5 through 8, significant numbers of outages have been required to deal with warranty inspections and equipment problems. Techniques have been developed to ensure that outages are properly planned and managed so that outage time is minimized, overtime is minimized, and capacity factor is maximized, while ensuring that personnel safety is not compromised. Successful outage planning and execution requires the commitment of many on-station and off-station resources groups. Coordination of all of these groups is required both before and during the outage to ensure outage time is not lost due to unavailability of men or equipment at the time they are required. This paper details the control processes that must be used prior to, during, and after an outage to ensure that time is not lost unnecessarily during outages. Successful outage management at Pickering Nuclear Generating Station can be subdivided into three stages; preoutage planning, outage execution, and postoutage review

Summary of operating experience in Swiss nuclear power plants 1994

International Nuclear Information System (INIS)

1995-05-01

In 1994 the Swiss nuclear power plants produced their highest-ever combined annual output. Their contribution to total electricity generation in the country was 36%. At Muehleberg the power uprate, undertaken in 1993, was effective for the first time for an entire year. The larger capacity of the new steam generators installed in 1993 in unit 1 of the Beznau NPP allows for an electric output of 103% of nominal power. The plant efficiency of the Goesgen and Leibstadt units was increased by replacing the low pressure turbines by the new ones with a modern design. The application for a power uprate of the Leibstadt reactor is still pending. For the first time in Switzerland, one of the reactor units, Beznau 2, operated on an extended cycle of one and a half years, with no refuelling outage in 1994. In spite of the replacements of two of its three low pressure turbines, Goesgen had the shortest refuelling shutdown since the start of commercial operation. The average number of reactor scrams at the Swiss plants remained stable, at less than one scram per reactor year. Re-inspection of crack indications detected in 1990 in the core shroud of the Muehleberg reactor revealed no significant changes. A crack indication was found in one of the other welds inspected. The Swiss government issued a limited operating licence for Beznau 2 for the next ten years, i.e. until the end of 2004. The only other unit with a limited operating licence (until 2003) is Muehleberg. The remaining three reactor units, have no time limits on their operating licences, in accordance with the Atomic Law. Goesgen is the first Swiss nuclear power plant having now produced more than 100 billion kWh. As from January 1, 1995, the nominal net power of the largest Swiss reactor unit, Leibstadt, has been fixed at 1030 MW; that of the Goesgen NPP has been increased by 25 MW to 965 MW. (author) figs., tabs

Summary of operating experience in Swiss nuclear power plants 1994

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-05-01

In 1994 the Swiss nuclear power plants produced their highest-ever combined annual output. Their contribution to total electricity generation in the country was 36%. At Muehleberg the power uprate, undertaken in 1993, was effective for the first time for an entire year. The larger capacity of the new steam generators installed in 1993 in unit 1 of the Beznau NPP allows for an electric output of 103% of nominal power. The plant efficiency of the Goesgen and Leibstadt units was increased by replacing the low pressure turbines by the new ones with a modern design. The application for a power uprate of the Leibstadt reactor is still pending. For the first time in Switzerland, one of the reactor units, Beznau 2, operated on an extended cycle of one and a half years, with no refuelling outage in 1994. In spite of the replacements of two of its three low pressure turbines, Goesgen had the shortest refuelling shutdown since the start of commercial operation. The average number of reactor scrams at the Swiss plants remained stable, at less than one scram per reactor year. Re-inspection of crack indications detected in 1990 in the core shroud of the Muehleberg reactor revealed no significant changes. A crack indication was found in one of the other welds inspected. The Swiss government issued a limited operating licence for Beznau 2 for the next ten years, i.e. until the end of 2004. The only other unit with a limited operating licence (until 2003) is Muehleberg. The remaining three reactor units, have no time limits on their operating licences, in accordance with the Atomic Law. Goesgen is the first Swiss nuclear power plant having now produced more than 100 billion kWh. As from January 1, 1995, the nominal net power of the largest Swiss reactor unit, Leibstadt, has been fixed at 1030 MW; that of the Goesgen NPP has been increased by 25 MW to 965 MW. (author) figs., tabs.

On test and maintenance: Optimization of allowed outage time

International Nuclear Information System (INIS)

Mavko, B.; Cepin, M.T.

2000-01-01

Probabilistic Safety Assessment is widely becoming standard method for assessing, maintaining, assuring and improving the nuclear power plant safety. To achieve one of its many potential benefits, the optimization of allowed outage time specified in technical specifications is investigated. Proposed is the risk comparison approach for evaluation of allowed outage time. The risk of shutting the plant down due to failure of certain equipment is compared to the risk of continued plant operation with the specified equipment down. The core damage frequency serves as a risk measure. (author)

Knowledge to Action - Understanding Natural Hazards-Induced Power Outage Scenarios for Actionable Disaster Responses

Science.gov (United States)

Kar, B.; Robinson, C.; Koch, D. B.; Omitaomu, O.

2017-12-01

The Sendai Framework for Disaster Risk Reduction 2015-2030 identified the following four priorities to prevent and reduce disaster risks: i) understanding disaster risk; ii) strengthening governance to manage disaster risk; iii) investing in disaster risk reduction for resilience and; iv) enhancing disaster preparedness for effective response, and to "Build Back Better" in recovery, rehabilitation and reconstruction. While forecasting and decision making tools are in place to predict and understand future impacts of natural hazards, the knowledge to action approach that currently exists fails to provide updated information needed by decision makers to undertake response and recovery efforts following a hazard event. For instance, during a tropical storm event advisories are released every two to three hours, but manual analysis of geospatial data to determine potential impacts of the event tends to be time-consuming and a post-event process. Researchers at Oak Ridge National Laboratory have developed a Spatial Decision Support System that enables real-time analysis of storm impact based on updated advisory. A prototype of the tool that focuses on determining projected power outage areas and projected duration of outages demonstrates the feasibility of integrating science with decision making for emergency management personnel to act in real time to protect communities and reduce risk.

Power allocation and achievable data rate in spectrum-sharing channels under adaptive primary service outage constraints

KAUST Repository

Yang, Yuli

2012-09-01

In this paper, we focus on a cognitive radio network where adaptive modulation is adopted in primary links. The gap between the primary user (PU)\\'s received signal-to-noise ratio (SNR) and the lower SNR boundary of the modulation mode that is being used, provides an interference-tolerable zone. Based on this gap, a secondary user (SU) has an increased opportunity to access the licensed spectrum and to determine the transmit power it should use to keep the PU\\'s quality-of-service (QoS) unaffected. However, since the SU cannot obtain perfect information on the PU\\'s received SNR, it has to choose an SNR point between the lower and upper boundaries of the PU\\'s current modulation mode as if this point were the real SNR received by the PU. Considering this issue, in order to quantify the effect of the SU\\'s transmissions on the PU\\'s QoS, we define the PU\\'s service outage probability and obtain its closed-form expressions by taking into account whether the peak transmit power constraint is imposed on the secondary\\'s transmission or not. Subsequently, we derive the SU\\'s achievable data rate in closed form for counterpart scenarios. Numerical results provided here quantify the relation between the PU\\'s service outage probability and the SU\\'s achievable data rate, which further demonstrate that the higher the peak transmit power a secondary transmitter can support, the better performance the cognitive radio network can achieve. © 2012 IEEE.

Assessing energy supply security: Outage costs in private households

International Nuclear Information System (INIS)

Praktiknjo, Aaron J.; Hähnel, Alexander; Erdmann, Georg

2011-01-01

The objective of this paper is to contribute to the topic of energy supply security by proposing a Monte Carlo-based and a survey based model to analyze the costs of power interruptions. Outage cost estimations are particularly important when deciding on investments to improve supply security (e.g. additional transmission lines) in order to compare costs to benefits. But also other policy decisions on measures that have direct or indirect consequences for the supply security (e.g. a phasing out of nuclear energy) need to be based on results from outage cost estimations. The main focus of this paper lies with residential consumers, but the model is applied to commercial, industrial and governmental consumers as well. There are limited studies that have approached the problem of evaluating outage cost. When comparing the results of these studies, they often display a high degree of diversification. As consumers have different needs and dependencies towards the supply of electricity because of varying circumstances and preferences, a great diversity in outage cost is a logical consequence. To take the high degree of uncertainties into account, a Monte Carlo simulation was conducted in this study for the case of private households in Germany. - Highlights: ► A macroeconomic model to assess outage cost is proposed. ► Possibilities for substitution are considered by analyzing individual preferences for the time-use. ► Uncertainties are taken into account by using a Monte Carlo simulation. ► This study reveals the distribution of outage costs to different electricity consumers. ► Implications for energy policy decisions are discussed.

Key Issues for the control of refueling outage duration and costs in PWR Nuclear Power Plants

International Nuclear Information System (INIS)

Degrave, Claude

2002-01-01

For several years, EDF, within the framework of the CIDEM1 project and in collaboration with some German Utilities, has undertaken a detailed review of the operating experience both of its own NPP and of foreign units, in order to improve the performances of future units under design, particularly the French-German European Pressurized Reactor (EPR) project. This review made it possible to identify the key issues allowing to decrease the duration of refueling and maintenance outages. These key issues can be classified in 3 categories Design, Maintenance and Logistic Support, Outage Management. Most of the key issues in the design field and some in the logistic support field have been studied and could be integrated into the design of any future PWR unit, as for the EPR project. Some of them could also be adapted to current plants, provided they are feasible and profitable. The organization must be tailored to each country, utility or period: it widely depends on the power production environment, particularly in a deregulation context. (author)

Thermal Hydraulic Assessment for Loss of SDCS Event During the Outage of CANDU Reactor

Energy Technology Data Exchange (ETDEWEB)

Kim, Jonghyun [Gnest, Inc. Taejon (Korea, Republic of); Lee, Kwangho; Oh, Haechol; Jun, Hwangyong [KEPRI, Taejon (Korea, Republic of)

2006-07-01

During the outage(overhaul) of the nuclear power plant, there are several operating states other than the full power state, that is 'Hot-Zero Power', 'Depressurized-Cooldown', and 'Partially Drained'. Until now safety assessment has not been done much for this operating state of CANDU type reactor worldwide. For the accuracy and confidence of PSA for the CANDU outage, the safety analysis is necessary. At the first stage, we analyzed the thermal hydraulic characteristics and safety of the postulated event of loss of shutdown cooling system (SDCS) during the partially drained state which is the longest one in the middle of outage period. As an analysis tool, this study uses the best estimate thermal hydraulic code, RELAP5/CANDU which was modified according to the CANDU specific characteristics and based on RELAP5.Mod3.

Integrated outage management: Leveraging utility system assets including GIS and AMR for optimum outage response

Energy Technology Data Exchange (ETDEWEB)

Finamore, E. P.

2004-02-01

The control of electrical system outages is discussed. The principal argument advanced is that traditional stand-alone methods of outage response will no longer get the job done without utility companies integrating their outage management systems with other system assets such as GIS (geographic information system) and AMR (advanced metering systems). Many meter reading systems, while primarily supporting customer billing, can also provide outage alarm and some are also capable of service restoration notification, which is an invaluable benefit to service operators since it obviates the need for verifying system restoration by labour-intensive on-site visits or customer call-backs. If successfully leveraged, optimization of all utility assets and improvements in labour productivity can results in improved outage management performance gains without affecting performance in other areas.

Outage Analysis and Optimization of SWIPT in Network-Coded Two-Way Relay Networks

Directory of Open Access Journals (Sweden)

Ruihong Jiang

2017-01-01

Full Text Available This paper investigates the outage performance of simultaneous wireless information and power transfer (SWIPT in network-coded two-way relay systems, where a relay first harvests energy from the signals transmitted by two sources and then uses the harvested energy to forward the received information to the two sources. We consider two transmission protocols, power splitting two-way relay (PS-TWR and time switching two-way relay (TS-TWR protocols. We present two explicit expressions for the system outage probability of the two protocols and further derive approximate expressions for them in high and low SNR cases. To explore the system performance limits, two optimization problems are formulated to minimize the system outage probability. Since the problems are nonconvex and have no known solution methods, a genetic algorithm- (GA- based algorithm is designed. Numerical and simulation results validate our theoretical analysis. It is shown that, by jointly optimizing the time assignment and SWIPT receiver parameters, a great performance gain can be achieved for both PS-TWR and TS-TWR. Moreover, the optimized PS-TWR always outperforms the optimized TS-TWR in terms of outage performance. Additionally, the effects of parameters including relay location and transmit powers are also discussed, which provide some insights for the SWIPT-enabled two-way relay networks.

[Responding to patients with home mechanical ventilation after the Great East Japan Earthquake and during the planned power outages. How should we be prepared for a future disaster ?].

Science.gov (United States)

Takechi, Yukako

2011-12-01

The unprecedented earthquake(magnitude-9 in the Japanese seismic intensity scale)hit off the east coast of Japan on March 11, 2011. Consequently, there were planned power outages in the area nearby Tokyo to avoid massive blackouts caused by a stoppage of Fukushima nuclear plants.Our clinic located in Kawasaki city was also hit by the earthquake(magnitude- 5).During the period of two months(March and April 2011), we had a total of 52 patients with home respiratory care (5-TPPV, 11-NPPV and 36-HOT)at that time.Two out of three 24 hour-TPPV users had no external battery.After the earthquake, there was a 7-hour electricity failure in some areas, and a patient with ASV(adaptive servo ventilator)was living there.Moreover, 3-hour/day power outages were carried out from March 14 to March 28, affecting people's everyday lives. However, the patient had no harmful influences from the power failure because a ventilation company lent us an external battery(4-9 hour life capacity)for the patients, and we were able to avoid an emergency situation caused by the power failure.In conclusion, we ought to be prepared for patients with home mechanical ventilation in the future toward unforeseen large scale power outages.

Modernization and power uprate of the Laguna Verde Nuclear Power Plant (Mexico); Modernizacion y aumento de potencia de la Central Nuclear Laguna Verde (Mexico)

Energy Technology Data Exchange (ETDEWEB)

Ruiz, L.; Merino, A.; Garcia-Serrano, J. L.

2012-11-01

The objective of this project is to perform the modifications on the thermal cycle of the plant required by an Extended Power Update, to achieve a safe and reliable operation of the plant at 120% of its original thermal power. The scope includes the design, engineering, training, supply of equipment, dismantling, installation, testing and commissioning. The duration of the project is 4,5 years (2007-2011), and all the modifications have been implemented in four outages, two per unit. The main modification carried out are the change of the condenser, moisture separator and main steam reheaters, the feedwater haters, the turbogenerator and its auxiliaries, transformers, isolated phase bus and main circuit breaker, etc. In this paper, the results obtained after all the modifications will be introduced. In addition, the most representative experience will be presented, as well as the lessons learned during the Project execution. (Author)

Management of planned unit outages

International Nuclear Information System (INIS)

Brune, W.

1984-01-01

Management of planned unit outages at the Bruno Leuschner Nuclear Power Plant is based on the experience gained with Soviet PWR units of the WWER type over a period of more than 50 reactor-years. For PWR units, planned outages concentrate almost exclusively on annual refuellings and major maintenance of the power plant facilities involved. Planning of such major maintenance work is based on a standardized basic network plan and a catalogue of standardized maintenance and inspection measures. From these, an overall maintenance schedule of the unit and partial process plans of the individual main components are derived (manually or by computer) and, in the temporal integration of major maintenance at every unit, fixed starting times and durations are determined. More than 75% of the maintenance work at the Bruno Leuschner Nuclear Power Plant is carried out by the plant's own maintenance personnel. Large-scale maintenance of every unit is controlled by a special project head. He is assisted by commissioners, each of whom is responsible for his own respective item. A daily control report is made. The organizational centre is a central office which works in shifts around the clock. All maintenance orders and reports of completion pass through this office; thus, the overall maintenance schedule can be corrected daily. To enforce the proposed operational strategy, suitable accompanying technical measures are required with respect to effective facility monitoring and technical diagnosis, purposeful improvement of particularly sensitive components and an increase in the effectiveness of maintenance work by special technologies and devices. (author)

The power outage of November 4, 2006: a plea for a genuine European energy policy

International Nuclear Information System (INIS)

Merlin, Andre

2006-01-01

As a power outage affected several millions European people in November 2006, this article identifies and discusses actions to be implemented at the European level to avoid such a situation and thus strengthen energy security for all European citizen. It proposes a detailed analysis of the situation of electricity transport grids before the incident, of what happened in terms of overloads for some very high voltage lines: the de-energizing of a line over the Ems River resulted in a domino triggering off of very high voltage lines connected to different areas of Europe; a decrease of current frequency resulted in the disconnection of power plants and grid managers had to reduce consumption in emergency. The article draws some early lessons of the incident before the UCTE (Power Transport Coordination Union) inquiry, and recommends some actions regarding grid coordination, harmonisation of abilities and decisions, and performance of provisional assessments of the electricity supply/demand balance

Use of a Computerized Tool (ORAM) to Help Manage Outage Safety and Risk at NPP Krsko

International Nuclear Information System (INIS)

Spiler, J.; Basic, I.; Vrbanic, I.; Fifnja, I.; Kastelan, M.; Dagan, W. J.; Shanley, L. B.; Naum, T. J.

1998-01-01

Outage Risk Assessment and Management (ORAM) is a computerized methodology developed by the U.S. Electric Power Research Institute (EPRI) to help Nuclear Power Plant personnel manage the risk and safety associated with refueling and forced plant outages. Today, over 60 plants including NPP Krsko are using ORAM during the preparation and performance of plant outages. In fact, many plants are attributing much of the reductions in the duration of refueling outages to the use of ORAM. The success of the ORAM methodology is the capability to provide plant and management personnel with understandable results from both deterministic evaluations of plant safety and quantitative risk assessments. The Nuklearna Elektrarna Krsko (NEK) use of ORAM involves both of these approaches. The deterministic portion of ORAM is used to model the NPP Krsko Shutdown Technical Specifications and administrative considerations. The probabilistic portion of ORAM uses industry and NEK specific initiating events and other risk elements pertaining to shutdown to derive a quantitative risk assessment for various end states, including core damage and RCS boiling. This paper expands on the value of each approach and demonstrates the benefits of combining these elements in the decision-making process. Another key advantage of ORAM is the ability to apply the methodology to specific outages. Since no outage is identical, this provides tremendous benefits to plant personnel for managing the safety and risk of a particular outage. ORAM does this ba organizing all of the various plant configurations and equipment unavailability windows into numerous plant states. Furthermore, ORAM evaluations can be a utomated b y interfacing with outage scheduling software programs such as Primavera. For each plant state, the deterministic and the probabilistic logic evaluations are applied. This paper will demonstrate the ORAM evaluation for an actual NPP Krsko outage. (author)

Recent Performance of and Plasma Outage Studies with the SNS H- Source

Energy Technology Data Exchange (ETDEWEB)

Stockli, Martin P [ORNL; Han, Baoxi [ORNL; Murray Jr, S N [ORNL; Pennisi, Terry R [ORNL; Piller, Chip [ORNL; Santana, Manuel [ORNL; Welton, Robert F [ORNL

2016-01-01

SNS ramps to higher power levels that can be sustained with high availability. The goal is 1.4 MW despite a compromised RFQ, which requires higher RF power than design levels to approach the nominal beam transmission. Unfortunately at higher power the RFQ often loses its thermal stability, a problem apparently enhanced by beam losses and high influxes of hydrogen. Delivering as much H- beam as possible with the least amount of hydrogen led to plasma outages. The root cause is the dense 1-ms long ~55-kW 2-MHz plasma pulses reflecting ~90% of the continuous ~300W, 13-MHz power, which was mitigated with a 4-ms filter for the reflected power signal and an outage resistant, slightly-detuned 13-MHz match. Lowering the H2 also increased the H- beam current to ~55 mA, and increased the transmission by ~7%.

Framatome ANP outage optimization support solutions

International Nuclear Information System (INIS)

Bombail, Jean Paul

2003-01-01

Over the last several years, leading plant operators have demonstrated that availability factors can be improved while safety and reliability can be enhanced on a long-term basis and operating costs reduced. Outage optimization is the new term being used to describe these long-term initiatives through which a variety of measures aimed at shortening scheduled plant outages have been developed and successfully implemented by these leaders working with their service providers who were introducing new technologies and process improvements. Following the leaders, all operators now have ambitious outage optimization plans and the median and average outage duration are decreasing world-wide. Future objectives are even more stringent and must include plant upgrades and component replacements being performed for life extension of plant operation. Outage optimization covers a broad range of activities from modifications of plant systems to faster cool down rates to human behavior improvements. It has been proven to reduce costs, avoid unplanned outages and thus support plant availability and help to ensure the utility's competitive position in the marketplace

Outage risk reduction at Diablo Canyon

International Nuclear Information System (INIS)

Burnett, Tobias W.T.; Eugene Newman, C.

2004-01-01

A formal risk reduction program was conducted at the Diablo Canyon Nuclear Generating plant as part of EPRI's Outage Risk Assessment and Management Program. The program began with a probabilistic and deterministic assessment of the frequency of core coolant boiling and core uncovery during shutdown operations. This step identified important contributors to risk, periods of high vulnerability, and potential mechanisms for reducing risk. Next, recovery strategies were evaluated and procedures, training, and outage schedules modified. Twelve risk reduction enhancements were developed and implemented. These enhancements and their impact are described in this paper. These enhancements reduced the calculated risk of core uncovery by about a factor of four for a refueling outage without lengthening the outage schedule; increased the outage efficiency, contributing to completing 11 days ahead of schedule; and helped to earn the highest achievable SALP rating from the NRC. (author)

Outage scheduling and implementation

International Nuclear Information System (INIS)

Allison, J.E.; Segall, P.; Smith, R.R.

1986-01-01

Successful preparation and implementation of an outage schedule and completion of scheduled and emergent work within an identified critical path time frame is a result of careful coordination by Operations, Work Control, Maintenance, Engineering, Planning and Administration and others. At the Fast Flux Test Facility (FFTF) careful planning has been responsible for meeting all scheduled outage critical paths

Improvement of availability of PWR nuclear plants through the reduction of the time required for refueling/maintenance outages

International Nuclear Information System (INIS)

Mayers, J.B.; Soth, L.G.

1978-04-01

The objective of the project, conducted by Commonwealth Research Corporation and Westinghouse Electric Corporation, is to identify improvements in procedures and equipment which will reduce the time required for refueling/maintenance outages at PWR nuclear power plants. The outage of Commonwealth Edison Zion Station Unit 1 in March through May of 1976 was evaluated to identify those items which caused delays and those work activities that offer the potential for significant improvements that could reduce the overall duration of the outage and achieve an improvement in the plant's availability for power production. Modifications in procedures have been developed and were evaluated during one or more outages in 1977. Conceptual designs have been developed for equipment modifications to the refueling system that could reduce the time required for the refueling portion of the outage. The purpose of the interim report is to describe those conceptual designs and to assess their impact upon future outages. Recommendations are included for the implementation of these equipment improvements in a continuation of this program as a demonstration of plant availability benefits that can be realized in PWR nuclear plants already in operation or under construction

Experience of oil in CANDU moderator during A831 planned outage at Bruce Power

International Nuclear Information System (INIS)

Ma, G.; Nashiem, R.; Matheson, S.; Stuart, C.; Roberts, J.G.

2011-01-01

In their address to the Nuclear Plant Chemistry Conference 2009, Bruce Power staff will describe the effects of oil ingress to the moderator of a CANDU reactor. During the A831 planned outage of Bruce Power Unit 3, an incident of oil ingress into moderator was discovered on Oct 17, 2008. An investigation identified the cause of the oil ingress. Atomic Energy of Canada Ltd. (AECL) assessed operability of the reactor with the oil present and made recommendations with respect to the effect on unit start-up with oil present. The principal concern was the radiolytic generation of deuterium from the breakdown of the oil in-core. Various challenges were presented during start-up which were overcome via innovative approaches. The subsequent actions and consequential effects on moderator chemistry are discussed in this paper. Examination of the plant chemistry data revealed some interesting aspects of moderator system chemistry under upset conditions which will also be presented. (author)

Experience of oil in CANDU® moderator during A831 planned outage at Bruce Power

International Nuclear Information System (INIS)

Ma, G.; Nashiem, R.; Matheson, S.; Stuart, C.; Roberts, J.G.

2010-01-01

In their address to the Nuclear Plant Chemistry Conference 2009, Bruce Power staff will describe the effects of oil ingress to the moderator of a CANDU® reactor. During the A831 planned outage of Bruce Power Unit 3, an incident of oil ingress into moderator was discovered on Oct 17, 2008. An investigation identified the cause of the oil ingress. Atomic Energy of Canada Ltd. (AECL) assessed operability of the reactor with the oil present and made recommendations with respect to the effect on unit start-up with oil present. The principal concern was the radiolytic generation of deuterium from the breakdown of the oil in-core. Various challenges were presented during start-up which were overcome via innovative approaches. The subsequent actions and consequential effects on moderator chemistry are discussed in this paper. Examination of the plant chemistry data revealed some interesting aspects of moderator system chemistry under upset conditions which will also be presented. (author)

Experience of oil in CANDU® moderator during A831 planned outage at Bruce Power

Energy Technology Data Exchange (ETDEWEB)

Ma, G.; Nashiem, R.; Matheson, S. [Bruce Power, Tiverton, Ontario (Canada); Stuart, C. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada); Roberts, J.G. [CANTECH Associates Ltd., Burlington, Ontario (Canada)

2010-07-01

In their address to the Nuclear Plant Chemistry Conference 2009, Bruce Power staff will describe the effects of oil ingress to the moderator of a CANDU® reactor. During the A831 planned outage of Bruce Power Unit 3, an incident of oil ingress into moderator was discovered on Oct 17, 2008. An investigation identified the cause of the oil ingress. Atomic Energy of Canada Ltd. (AECL) assessed operability of the reactor with the oil present and made recommendations with respect to the effect on unit start-up with oil present. The principal concern was the radiolytic generation of deuterium from the breakdown of the oil in-core. Various challenges were presented during start-up which were overcome via innovative approaches. The subsequent actions and consequential effects on moderator chemistry are discussed in this paper. Examination of the plant chemistry data revealed some interesting aspects of moderator system chemistry under upset conditions which will also be presented. (author)

Experience of oil in CANDU moderator during A831 planned outage at Bruce Power

Energy Technology Data Exchange (ETDEWEB)

Ma, G.; Nashiem, R.; Matheson, S. [Bruce Power, Tiverton, Ontario (Canada); Stuart, C. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada); Roberts, J.G. [CANTECH Associates Ltd., Burlington, Ontario (Canada)

2011-03-15

In their address to the Nuclear Plant Chemistry Conference 2009, Bruce Power staff will describe the effects of oil ingress to the moderator of a CANDU reactor. During the A831 planned outage of Bruce Power Unit 3, an incident of oil ingress into moderator was discovered on Oct 17, 2008. An investigation identified the cause of the oil ingress. Atomic Energy of Canada Ltd. (AECL) assessed operability of the reactor with the oil present and made recommendations with respect to the effect on unit start-up with oil present. The principal concern was the radiolytic generation of deuterium from the breakdown of the oil in-core. Various challenges were presented during start-up which were overcome via innovative approaches. The subsequent actions and consequential effects on moderator chemistry are discussed in this paper. Examination of the plant chemistry data revealed some interesting aspects of moderator system chemistry under upset conditions which will also be presented. (author)

Loss of benefits resulting from nuclear-power-plant outages. Volume 1. Approach and analysis

International Nuclear Information System (INIS)

Buehring, W.A.; Peerenboom, J.P.

1982-03-01

This report discusses and analyzes some of the important consequences of nuclear-power-plant unavailability, and quantifies a number of technical measures of loss of benefits that may help the Nuclear Regulatory Commission make decisions involving nuclear-power-plant licensing and operation. The consequences include increased costs of system generation, increased demand for nonnuclear and often scarce fuels, and reduced system reliability. Argonne National Laboratory (ANL) developed case studies to investigate the effects of hypothetical nuclear-plant shutdowns. The studies developed quantitative measures of both short- and long-term economic, fuel use, and reliability effects that could result from the unavailability of nuclear generating units. Results showed that production costs (fuel costs plus operation and maintenance costs) increase significantly whenever an operating reactor is shut down. Production-cost increases ranged from less than 10% to over 60%; the normalized increases for the first year of reactor outage ranged from $0.125 million per MWe-year to $0.33 million per MWe-year

A Study on the Frequency of Initiating Event of OPR-1000 during Outage Periods

Energy Technology Data Exchange (ETDEWEB)

Hong Jae Beol; Jae, Moo Sung [Hanyang Univ., Seoul (Korea, Republic of)

2013-10-15

These sources of data did not reflect the latest event data which have occurred during the PWR outage to the frequencies of initiating event Electric Power Research Institute(EPRI) in USA collected the data of loss of decay heat removal during outage from 1989 to 2009 and published technical report. Domestic operating experiences for LOOP is gathered in Operational Performance Information System for Nuclear Power Plant(OPIS). To reduce conservatism and obtain completeness for LPSD PSA, those data should be collected and used to update the frequencies. The frequencies of LOSDC and LOOP are reevaluated using the data of EPRI and OPIS in this paper. Quantification is conducted to recalculate core damage frequency(CDF), since the rate is changed. The results are discussed below. To make an accurate estimate of the initiating events of LPSD PSA, the event data were collected and the frequencies of initiating events were updated using Bayesian approach. CDF was evaluated through quantification. Δ CDF is -40% and the dominant contributor is pressurizer PSV stuck open event. The most of the event data in EPRI TR were collected from US nuclear power plant industry. Those data are not enough to evaluate outage risk precisely. Therefore, to reduce conservatism and obtain completeness for LPSD PSA, the licensee event report and domestic data should be collected and reflected to the frequencies of the initiating events during outage.

Outage performance of cognitive radio systems with Improper Gaussian signaling

KAUST Repository

Amin, Osama; Abediseid, Walid; Alouini, Mohamed-Slim

2015-01-01

design the SU signal by adjusting its transmitted power and the circularity coefficient to minimize the SU outage probability while maintaining a certain PU quality-of-service. Finally, we evaluate the proposed bounds and adaptive algorithms by numerical

How individual traces and interactive timelines could support outage execution - Toward an outage historian concept

International Nuclear Information System (INIS)

Parfouru, S.; De-Beler, N.

2012-01-01

In the context of a project that is designing innovative ICT-based solutions for the organizational concept of outage management, we focus on the informational process of the OCR (Outage Control Room) underlying the execution of the outages. Informational process are based on structured and unstructured documents that have a key role in the collaborative processes and management of the outage. We especially track the structured and unstructured documents, electronically or not, from creation to sharing. Our analysis allows us to consider that the individual traces produced by an individual participant with a specific role could be multi-purpose and support sharing between participants without creating duplication of work. The ultimate goal is to be able to generate an outage historian, that is not just focused on highly structured information, which could be useful to improve the continuity of information between participants. We study the implementation of this approach through web technologies and social media tools to address this issue. We also investigate the issue of data access through interactive visualization timelines coupled with other modality's to assist users in the navigation and exploration of the proposed historian. (authors)

Major outage trends in light water reactors. Interim report

International Nuclear Information System (INIS)

Burns, E.T.

1978-04-01

The report is a summary of the major outages which occurred in light water reactor plants during the period January 1971 through June 1977. Only those outages greater than 100 hours duration (exclusive of refueling outages) are included in the report. The trends in outages related to various reactor systems and components are presented as a function of plant age, and alternatively, calendar year. The principal contributors to major outages are ranked by their effect on the overall outage time for PWRs and BWRs. In addition, the outage history of each operating nuclear plant greater than 150 MWe is presented, along with a brief summary of those outages greater than two months duration

Operational readiness verification, phase 1: A study on safety during outage and restart of nuclear power plants

Energy Technology Data Exchange (ETDEWEB)

Hollnagel, E. [Linkoeping Univ. (Sweden). Dept. of Computer and Information Science; Gauthereau, V. [Linkoeping Univ. (Sweden). Dept. of Industrial Engineering

2001-06-01

This report contains the findings from the first phase of a study on safety during outage and restart of nuclear power plants. Operational Readiness Verification (ORV) - in Swedish called Driftklarhetsverifiering (DKV) - refers to the test and verification activities that are necessary to ensure that plant systems are able to provide their required functions when needed - more concretely that all plant systems are in their correct functional state when the plant is restarted after an outage period. The concrete background for this work is that nine ORV related incidents were reported in Sweden between July 1995 and October 1998. The work reported here comprised a literature survey of research relevant for ORV issues, and an assessment of the present situation at Swedish NPPs with respect to ORV. The literature survey was primarily aimed at research related to NPPs, but also looked at domains where similar problems have occurred, such as maintenance in commercial aviation. The survey looked specifically for organisational and MTO aspects relevant to the present situation in Swedish NPPs. One finding was that ORV should be seen as an integral part of maintenance, rather than as a separate activity. Another, that there is a characteristic distribution of error modes for maintenance and ORV, with many sequence errors and omissions, rather than a set of unique error modes. An international study further showed that there are important differences in how procedures are used, and in the balance between decentralisation and centralisation. Several studies also suggested that ORV could usefully be described as a barrier system in relation to the flow of work, for instance using the following five stages: (1) preventive actions during maintenance/outage, (2) post-test after completion of work, (3) pre-test before start-up, (4) the start-up sequence itself, and (5) preventive actions during power operation - possibly including automatic safety systems. In the field survey

Operational readiness verification, phase 1: A study on safety during outage and restart of nuclear power plants

International Nuclear Information System (INIS)

Hollnagel, E.; Gauthereau, V.

2001-06-01

This report contains the findings from the first phase of a study on safety during outage and restart of nuclear power plants. Operational Readiness Verification (ORV) - in Swedish called Driftklarhetsverifiering (DKV) - refers to the test and verification activities that are necessary to ensure that plant systems are able to provide their required functions when needed - more concretely that all plant systems are in their correct functional state when the plant is restarted after an outage period. The concrete background for this work is that nine ORV related incidents were reported in Sweden between July 1995 and October 1998. The work reported here comprised a literature survey of research relevant for ORV issues, and an assessment of the present situation at Swedish NPPs with respect to ORV. The literature survey was primarily aimed at research related to NPPs, but also looked at domains where similar problems have occurred, such as maintenance in commercial aviation. The survey looked specifically for organisational and MTO aspects relevant to the present situation in Swedish NPPs. One finding was that ORV should be seen as an integral part of maintenance, rather than as a separate activity. Another, that there is a characteristic distribution of error modes for maintenance and ORV, with many sequence errors and omissions, rather than a set of unique error modes. An international study further showed that there are important differences in how procedures are used, and in the balance between decentralisation and centralisation. Several studies also suggested that ORV could usefully be described as a barrier system in relation to the flow of work, for instance using the following five stages: (1) preventive actions during maintenance/outage, (2) post-test after completion of work, (3) pre-test before start-up, (4) the start-up sequence itself, and (5) preventive actions during power operation - possibly including automatic safety systems. In the field survey

Operational readiness verification, phase 1: A study on safety during outage and restart of nuclear power plants

Energy Technology Data Exchange (ETDEWEB)

Hollnagel, E [Linkoeping Univ. (Sweden). Dept. of Computer and Information Science; Gauthereau, V [Linkoeping Univ. (Sweden). Dept. of Industrial Engineering

2001-06-01

This report contains the findings from the first phase of a study on safety during outage and restart of nuclear power plants. Operational Readiness Verification (ORV) - in Swedish called Driftklarhetsverifiering (DKV) - refers to the test and verification activities that are necessary to ensure that plant systems are able to provide their required functions when needed - more concretely that all plant systems are in their correct functional state when the plant is restarted after an outage period. The concrete background for this work is that nine ORV related incidents were reported in Sweden between July 1995 and October 1998. The work reported here comprised a literature survey of research relevant for ORV issues, and an assessment of the present situation at Swedish NPPs with respect to ORV. The literature survey was primarily aimed at research related to NPPs, but also looked at domains where similar problems have occurred, such as maintenance in commercial aviation. The survey looked specifically for organisational and MTO aspects relevant to the present situation in Swedish NPPs. One finding was that ORV should be seen as an integral part of maintenance, rather than as a separate activity. Another, that there is a characteristic distribution of error modes for maintenance and ORV, with many sequence errors and omissions, rather than a set of unique error modes. An international study further showed that there are important differences in how procedures are used, and in the balance between decentralisation and centralisation. Several studies also suggested that ORV could usefully be described as a barrier system in relation to the flow of work, for instance using the following five stages: (1) preventive actions during maintenance/outage, (2) post-test after completion of work, (3) pre-test before start-up, (4) the start-up sequence itself, and (5) preventive actions during power operation - possibly including automatic safety systems. In the field survey

Upgrading BWR training simulators for annual outage operation training

International Nuclear Information System (INIS)

Yamakabe, K.; Nakajima, A.; Shiyama, H.; Noji, K.; Okabe, N.; Murata, F.

2006-01-01

Based upon the recently developed quality assurance program by the Japanese electric companies, BWR Operator Training Center (BTC) identified the needs to enhance operators' knowledge and skills for operations tasks during annual outage, and started to develop a dedicated operator training course specialized for them. In this paper, we present the total framework of the training course for annual outage operations and the associated typical three functions of our full-scope simulators specially developed and upgraded to conduct the training; namely, (1) Simulation model upgrade for the flow and temperature behavior concerning residual heat removal (RHR) system with shutdown cooling mode, (2) Addition of malfunctions for DC power supply equipment, (3) Simulation model upgrade for water filling operation for reactor pressurization (future development). We have implemented a trial of the training course by using the upgraded 800MW full-scope training simulator with functions (1) and (2) above. As the result of this trial, we are confident that the developed training course is effective for enhancing operators' knowledge and skills for operations tasks during annual outage. (author)

Advanced Test Reactor outage risk assessment

International Nuclear Information System (INIS)

Thatcher, T.A.; Atkinson, S.A.

1997-01-01

Beginning in 1997, risk assessment was performed for each Advanced Test Reactor (ATR) outage aiding the coordination of plant configuration and work activities (maintenance, construction projects, etc.) to minimize the risk of reactor fuel damage and to improve defense-in-depth. The risk assessment activities move beyond simply meeting Technical Safety Requirements to increase the awareness of risk sensitive configurations, to focus increased attention on the higher risk activities, and to seek cost-effective design or operational changes that reduce risk. A detailed probabilistic risk assessment (PRA) had been performed to assess the risk of fuel damage during shutdown operations including heavy load handling. This resulted in several design changes to improve safety; however, evaluation of individual outages had not been performed previously and many risk insights were not being utilized in outage planning. The shutdown PRA provided the necessary framework for assessing relative and absolute risk levels and assessing defense-in-depth. Guidelines were written identifying combinations of equipment outages to avoid. Screening criteria were developed for the selection of work activities to receive review. Tabulation of inherent and work-related initiating events and their relative risk level versus plant mode has aided identification of the risk level the scheduled work involves. Preoutage reviews are conducted and post-outage risk assessment is documented to summarize the positive and negative aspects of the outage with regard to risk. The risk for the outage is compared to the risk level that would result from optimal scheduling of the work to be performed and to baseline or average past performance

Three dimensional considerations in thermal-hydraulics of helical cruciform fuel rods for LWR power uprates

Energy Technology Data Exchange (ETDEWEB)

Shirvan, Koroush, E-mail: kshirvan@mit.edu; Kazimi, Mujid S.

2014-04-01

Highlights: • We benchmarked the 4 × 4 helical cruciform fuel (HCF) bundle pressure drop experimental data with CFD. • We also benchmarked the 4 × 4 HCF mixing experimental data with CFD. • We derived new friction factors for PWR and BWR designs at PWR and BWR operating conditions from CFD. • We showed the importance of modeling the 3D conduction in HCF in steady state and transient conditions. - Abstract: In order to increase the power density of current and new light water reactor designs, the helical cruciform fuel (HCF) rods have been proposed. The HCF rod is equivalent to a thin cylindrical rod, with 4 fuel containing vanes, wrapped around it. The HCF rods increase the surface area to volume ratio of the fuel and enhance the inter-subchannel mixing due to their helical shape. The rods do not need supporting grids, as they are packed to periodically contact their neighbors along the flow direction, enabling a higher power density in the core. The HCF rods were reported to have the potential to uprate existing PWRs by 45% and BWRs by 20%. In order to quantify the mixing behavior of the HCF rods based on their twist pitch, experiments were previously performed at atmospheric pressures with single phase water in a 4 by 4 HCF and cylindrical rod bundles. In this paper, the experimental results on pressure drop and mixing are benchmarked with computational fluid dynamic (CFD) using steady state the Reynolds average Navier–Stokes (RANS) turbulence model. The sensitivity of the CFD approach to computational domain, mesh size, mesh shape and RANS turbulence models are examined against the experimental conditions. Due to the refined radial velocity profile from the HCF rods twist, the turbulence models showed little sensitivity to the domain. Based on the CFD simulations, the total pressure drops under the PWR and BWR conditions are expected to be about 10% higher than the values previously reported solely from an empirical correlation based on the

Optimization of safety equipment outages improves safety

International Nuclear Information System (INIS)

Cepin, Marko

2002-01-01

Testing and maintenance activities of safety equipment in nuclear power plants are an important potential for risk and cost reduction. An optimization method is presented based on the simulated annealing algorithm. The method determines the optimal schedule of safety equipment outages due to testing and maintenance based on minimization of selected risk measure. The mean value of the selected time dependent risk measure represents the objective function of the optimization. The time dependent function of the selected risk measure is obtained from probabilistic safety assessment, i.e. the fault tree analysis at the system level and the fault tree/event tree analysis at the plant level, both extended with inclusion of time requirements. Results of several examples showed that it is possible to reduce risk by application of the proposed method. Because of large uncertainties in the probabilistic safety assessment, the most important result of the method may not be a selection of the most suitable schedule of safety equipment outages among those, which results in similarly low risk. But, it may be a prevention of such schedules of safety equipment outages, which result in high risk. Such finding increases the importance of evaluation speed versus the requirement of getting always the global optimum no matter if it is only slightly better that certain local one

Outage analysis of blind cooperative diversity

KAUST Repository

Tourki, Kamel; Alouini, Mohamed-Slim

2011-01-01

Mobile users with single antennas can still take advantage of spatial diversity through cooperative space-time-encoded transmission. In this paper, we considered a scheme in which a relay chooses to cooperate only if its source-relay channel is of an acceptable quality, and we evaluate the usefulness of relaying when the source acts blindly and ignores the decision of the relays whether they may cooperate or not. In our study, we consider the regenerative relays in which the decisions to cooperate are based on a targeted end-to-end data rate R. We derived the end-to-end outage probability for a transmission rate R and a code rate ρ and look at a power allocation strategy between the source and the relays in order to minimize the end-to-end outage probability at the destination for high signal-to-noise ratio, by using the golden section search method. Performance results show that the computer simulations-based results coincide with our analytical results. Copyright © 2011 John Wiley & Sons, Ltd.

Outage analysis of blind cooperative diversity

KAUST Repository

Tourki, Kamel

2011-06-06

Mobile users with single antennas can still take advantage of spatial diversity through cooperative space-time-encoded transmission. In this paper, we considered a scheme in which a relay chooses to cooperate only if its source-relay channel is of an acceptable quality, and we evaluate the usefulness of relaying when the source acts blindly and ignores the decision of the relays whether they may cooperate or not. In our study, we consider the regenerative relays in which the decisions to cooperate are based on a targeted end-to-end data rate R. We derived the end-to-end outage probability for a transmission rate R and a code rate ρ and look at a power allocation strategy between the source and the relays in order to minimize the end-to-end outage probability at the destination for high signal-to-noise ratio, by using the golden section search method. Performance results show that the computer simulations-based results coincide with our analytical results. Copyright © 2011 John Wiley & Sons, Ltd.

An exact power series formula of the outage probability with noise and interference over generalized fading channels

KAUST Repository

Rached, Nadhir B.

2016-12-24

In this paper, we develop a generalized momentbased approach for the evaluation of the outage probability (OP) in the presence of co-channel interference and additive white Gaussian noise. The proposed method allows the evaluation of the OP of the signal-to-interference-plus-noise ratio by a power series expansion in the threshold value. Its main advantage is that it does not require a particular distribution for the interference channels. The only necessary ingredients are a power series expansion for the cumulative distribution function of the desired user power and the cross-moments of the interferers\\' powers. These requirements are easily met in many practical fading models, for which the OP might not be obtained in closed-form expression. For a sake of illustration, we consider the application of our method to the Rician fading environment. Under this setting, we carry out a convergence study of the proposed power series and corroborate the validity of our method for different values of fading parameters and various numbers of co-channel interferers.

Standard plants, standard outages: the EdF approach

International Nuclear Information System (INIS)

Miron, J.L.

1991-01-01

At the end of 1990 Electricite de France had carried out a total of 350 PWR refuelling outages. Although the French units are standardized the routine of the outages are not all the same. The major influences on outages were: setting up new organizations to apply quality assurance regulations; improving systematic experience feedback; incorporating modifications in the outage schedules; assumilation of computerized maintenance management by the sites. (author)

Status Report on the Development of Micro-Scheduling Software for the Advanced Outage Control Center Project

Energy Technology Data Exchange (ETDEWEB)

Germain, Shawn St. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Thomas, Kenneth [Idaho National Lab. (INL), Idaho Falls, ID (United States); Farris, Ronald [Idaho National Lab. (INL), Idaho Falls, ID (United States); Joe, Jeffrey [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2014-09-01

The long-term viability of existing nuclear power plants (NPPs) in the United States (U.S.) is dependent upon a number of factors, including maintaining high capacity factors, maintaining nuclear safety, and reducing operating costs, particularly those associated with refueling outages. Refueling outages typically take 20-30 days, and for existing light water NPPs in the U.S., the reactor cannot be in operation during the outage. Furthermore, given that many NPPs generate between $1-1.5 million/day in revenue when in operation, there is considerable interest in shortening the length of refueling outages. Yet, refueling outages are highly complex operations, involving multiple concurrent and dependent activities that are difficult to coordinate. Finding ways to improve refueling outage performance while maintaining nuclear safety has proven to be difficult. The Advanced Outage Control Center project is a research and development (R&D) demonstration activity under the Light Water Reactor Sustainability (LWRS) Program. LWRS is a R&D program which works with industry R&D programs to establish technical foundations for the licensing and managing of long-term, safe, and economical operation of current NPPs. The Advanced Outage Control Center project has the goal of improving the management of commercial NPP refueling outages. To accomplish this goal, this INL R&D project is developing an advanced outage control center (OCC) that is specifically designed to maximize the usefulness of communication and collaboration technologies for outage coordination and problem resolution activities. This report describes specific recent efforts to develop a capability called outage Micro-Scheduling. Micro-Scheduling is the ability to allocate and schedule outage support task resources on a sub-hour basis. Micro-Scheduling is the real-time fine-tuning of the outage schedule to react to the actual progress of the primary outage activities to ensure that support task resources are

Outage planning in nuclear power plants. A paradigm shift from an external towards an integrated project planning tool

Energy Technology Data Exchange (ETDEWEB)

Rosemann, Andreas [Gesellschaft fuer integrierte Systemplanung (GIS) mbH, Weinheim (Germany)

2014-07-01

Latest demands on nuclear plant inspections are the ongoing actualisation of the outage plan on the basis of the current work progress and current events as well as the permanent access to the current planning status and work process of all people involved in the outage. Modern EAM systems (EAM: Enterprise Application Management) made up ground on established project planning tools with regard to functionalities for scheduling work orders. A shift towards an integrated planning in the EAM system increases the efficiency in the outage planning and improves the communication of current states of planning. (orig.)

Outage planning in nuclear power plants. A paradigm shift from an external towards an integrated project planning tool

International Nuclear Information System (INIS)

Rosemann, Andreas

2014-01-01

Latest demands on nuclear plant inspections are the ongoing actualisation of the outage plan on the basis of the current work progress and current events as well as the permanent access to the current planning status and work process of all people involved in the outage. Modern EAM systems (EAM: Enterprise Application Management) made up ground on established project planning tools with regard to functionalities for scheduling work orders. A shift towards an integrated planning in the EAM system increases the efficiency in the outage planning and improves the communication of current states of planning. (orig.)

Reactor refurbishment in an outage environment

International Nuclear Information System (INIS)

Gowthorpe, P.; Hoare, R.

2012-01-01

Reactor life extension has typically been performed during specific refurbishment outages. These outages are long and costly due to the sheer complexity of the scope, not to mention the ever present discovery work. A scope of this size requires a huge labour force to execute, which poses significant challenges. The work is difficult to staff with qualified people able to execute the work smoothly and managing the required labour pool problematic. Cost and time overruns are inevitable in that environment. Reducing the cost and schedule is critical to the long term viability of reactor refurbishment projects. With planning, the total cost of the refurbishment can be reduced by managing the inspection and repairs during normal outages. Identifying what activities need to be done each outage for the life of the reactor and bringing the latest technology can make this viable. Tightly planned outages with a small well trained labour force will go a long way to reducing costs. The suite of services and tooling available to the utilities to manage their reactor integrity has improved significantly in recent years and continues to evolve. New feeder inspection technologies can provide improved inspection results for the complex feeder geometry. These improvements lead to more accurate wear rates and better predictions of component life. Feeders that need replacement based on improved inspection techniques can be replaced systematically during regular outages rather than specific refurbishment outages. Targeting areas rather than entire feeders reduces time, dose and cost. In cases where feeder replacement isn't feasible or where unpredicted wear is found, a feeder weld overlay process can be used. To manage the reactor work, new data systems are under development that allow for effective tracking of each activity performed and outcomes in a single package. (author)

Practice of fuel management and outage strategy at Paks NPP

International Nuclear Information System (INIS)

Farago, P.; Hamvas, I.; Szecsenyi, Zs.; Nemes, I.; Javor, E.

2000-01-01

The Paks Nuclear Power Plant generates almost 40% of Hungarian electricity production at lowest price. In spite of this fact the reduction of operational and maintenance costs is one of the most important goal of the plant management. The proper fuel management and outage strategy can give a considerable influence for this cost reduction. The aim of loading pattern planning is to get the required cycle length with available fuel cassettes and to keep all key parameters of safety analysis under safety limits. Another important point is production at profit, where both the fuel and spent fuel cost are determining. Earlier the conditions given by our only fuel supplier restricted our possibilities, so at the beginning the fuel arrangement changing was the only way to improve efficiency of fuel using. As first step we introduced the low leakage core design. The next step was the 4 years cycle using of some cassettes. By this way nearly half of 3 years cycle old cassettes remained in the core for fourth cycle. In the immediate future we want to use profiled cassettes developed by Russian supplier. Simultaneously we will load new type of WWER cassettes with burnable poison developed by BNFL Company. Hereby we can apply more BNFL cassettes for four years cycle even more. Both cost of fuel and number of spent fuel can be reduced besides keeping parameters under safety limits. The Hungarian in service inspection rules determine that every four year we have to make a complete inspection of reactor vessel. Therefore earlier we had two types of outages. Every 4 years we planned a long outage with 55-65 days duration and normal ones with about 30-35 days duration between the long ones. During the normal outages this way did not give us enough room to utilise the shortest possible critical path determined by works on reactor. Some years ago we changed our outage strategy. Now we plan every 4 years a long outage, and between them one normal and two short ones. As a result the

Areva: experiences in outage services

International Nuclear Information System (INIS)

Wiemeier, R.; Mueller, N.; Blanco, I. J.

2010-01-01

As the world leader in the nuclear industry, Areva is firmly committed to the safe and reliable operation of the Spanish nuclear power plants. Following this commitment, Areva has established the subsidiary Areva NP Services Spain as a local platform to provide nuclear services for the Spanish nuclear power plants. being integrated and supported by the global Areva Group, Areva NP Services Spain is able to offer services solutions to all customers demands while maintaining close and sustainable relationships with them. This integration also allows the Spanish personnel of Areva to employ their skills by working in multinational teams in international projects. This article will present the capacities, and the most important recent national and international project performed by Areva NP Services Spain in the field of outage services. (Author)

Integrated head area design of KNGR to reduce refueling outage duration

Energy Technology Data Exchange (ETDEWEB)

Jeong, Woo Tae; Park, Chi Yong; Kim, In Hwan; Kim, Dae Woong [Korea Electric Power Research Institute, Taejon (Korea, Republic of)

1998-12-31

In the design of KNGR (Korea Next Generation Reactor), we believe that economy is one of the most important factors to be considered. Thus, we reviewed and evaluated the consequences of designing the head area into an integrated package from an economical point of view. The refueling outage durations of the nuclear power plants currently in operation in Korea, some having and others not having integrated head package, are compared. This paper discusses the characteristics of head area design and the critical design issues of KNGR head area to evaluate the effect of the head area characteristics on the outage duration. 8 refs., 4 figs. (Author)

Integrated head area design of KNGR to reduce refueling outage duration

Energy Technology Data Exchange (ETDEWEB)

Jeong, Woo Tae; Park, Chi Yong; Kim, In Hwan; Kim, Dae Woong [Korea Electric Power Research Institute, Taejon (Korea, Republic of)

1997-12-31

In the design of KNGR (Korea Next Generation Reactor), we believe that economy is one of the most important factors to be considered. Thus, we reviewed and evaluated the consequences of designing the head area into an integrated package from an economical point of view. The refueling outage durations of the nuclear power plants currently in operation in Korea, some having and others not having integrated head package, are compared. This paper discusses the characteristics of head area design and the critical design issues of KNGR head area to evaluate the effect of the head area characteristics on the outage duration. 8 refs., 4 figs. (Author)

Resolving piping analysis issues to minimize impact on installation activities during refueling outage at nuclear power plants

International Nuclear Information System (INIS)

Bhavnani, D.

1996-01-01

While it is required to maintain piping code compliance for all phases of installation activities during outages at a nuclear plant, it is equally essential to reduce challenges to the installation personnel on how plant modification work should be performed. Plant betterment activities that incorporate proposed design changes are continually implemented during the outages. Supporting analysis are performed to back these activities for operable systems. The goal is to reduce engineering and craft man-hours and minimize outage time. This paper outlines how plant modification process can be streamlined to facilitate construction teams to do their tasks that involve safety related piping. In this manner, installation can proceed by minimizing on the spot analytical effort and reduce downtime to support the proposed modifications. Examples are provided that permit performance of installation work in any sequence. Piping and hangers including the branch lines are prequalified and determined operable. The system is up front analyzed for all possible scenarios. The modification instructions in the work packages is flexible enough to permit any possible installation sequence. The benefit to this approach is large enough in the sense that valuable outage time is not extended and on site analytical work is not required

Steam separator uprating by elimination of capacity-limiting mechanisms

International Nuclear Information System (INIS)

Parkinson, J.R.; Pruster, W.P.; Kidwell, J.H.; Schneider, W.G.

1985-01-01

Advanced steam/water separation equipment for nuclear steam generator application is required for new equipment manufacture and also for retrofit. For new equipment applications, the desire for higher capacity is driven by competitiveness which requires maximum throughput in the most compact package. For retrofit applications, which have arisen due to the poor performance of some of the original equipment, the need is for high capacity separators which can fit into the existing pressure vessel envelope and not only correct the performance problem, but also allow for uprated plant output. This paper describes the development of such advanced steam separators

Studi Pengaruh Pemasangan NGR 40 Ohm pada Uprating Transformator 2 GI Gianyar Terhadap Gangguan Hubung Singkat 1 Phasa Tanah

Directory of Open Access Journals (Sweden)

Arya Surya Darma

2017-08-01

Full Text Available Along with the development of ever-increasing burden on the GI Gianyar then the transformer unit 2 with a capacity of 30 MVA will be uprating with a capacity of 60 MVA transformer. To maintain the continuity and reliability of the flow of electrical power to the consumer , NGR (Neutral Grounding Resistance and relay SBEF is used as the safety equipment of the short circuit 1 phase to ground was not in to the neutral point of the transformer. Uprating of transformers that have been done changes on 1 phase fault current to ground when using a direct earthing systems with a value to become 1838.21 A. While the value of the short-circuit current 1 phase to ground after pairing NGR 40 Ohm value is fixed at 288.675 A, so that the current setting and time relay SBEF fixed at 90 A and 7.067 seconds. The analysis result from the effect of installation NGR and rele SBEF on the transformer 60 MVA against short circuit 1 phase to ground has the ability good protection for the value of the fault current is able to be reduced from 1838,21 A into 288.675 A after pairing NGR 40 Ohm and time is needed SBEF to handle distractions 7.067 seconds. Intisari- Seiring dengan perkembangan beban yang terus meningkat di GI Gianyar maka transformator unit 2 berkapasitas 30 MVA akan di lakukan uprating (penggantian dengan transformator berkapasitas 60 MVA. Untuk menjaga kontinyuitas dan keandalan aliran daya listrik sampai ke konsumen (beban, NGR (Neutral Grounding Resistance dan rele SBEF dipergunakan sebagai peralatan pengaman dari gangguan hubung singkat phasa tanah agar arus gangguan 1 phasa ke tanah tidak sampai mengalir ke titik netral transformator. Dari uprating transformator yang sudah di lakukan terjadi perubahan pada arus gangguan 1 phasa ke tanah jika menggunakan sistem pentanahan langsung (solid grounding menjadi 1838,21 A. Sedangkan nilai dari arus hubung singkat 1 phasa ke tanah setelah dipasangkan NGR 40 Ohm nilainya tetap sebesar 288,675 A

Technology Integration Initiative In Support of Outage Management

Energy Technology Data Exchange (ETDEWEB)

Gregory Weatherby; David Gertman

2012-07-01

Plant outage management is a high priority concern for the nuclear industry from cost and safety perspectives. Often, command and control during outages is maintained in the outage control center where many of the underlying technologies supporting outage control are the same as those used in the 1980’s. This research reports on the use of advanced integrating software technologies and hand held mobile devices as a means by which to reduce cycle time, improve accuracy, and enhance transparency among outage team members. This paper reports on the first phase of research supported by the DOE Light Water Reactor Sustainability (LWRS) Program that is performed in close collaboration with industry to examine the introduction of newly available technology allowing for safe and efficient outage performance. It is thought that this research will result in: improved resource management among various plant stakeholder groups, reduced paper work, and enhanced overall situation awareness for the outage control center management team. A description of field data collection methods, including personnel interview data, success factors, end-user evaluation and integration of hand held devices in achieving an integrated design are also evaluated. Finally, the necessity of obtaining operations cooperation support in field studies and technology evaluation is acknowledged.

Outage Probability Analysis of FSO Links over Foggy Channel

KAUST Repository

Esmail, Maged Abdullah

2017-02-22

Outdoor Free space optic (FSO) communication systems are sensitive to atmospheric impairments such as turbulence and fog, in addition to being subject to pointing errors. Fog is particularly severe because it induces an attenuation that may vary from few dBs up to few hundreds of dBs per kilometer. Pointing errors also distort the link alignment and cause signal fading. In this paper, we investigate and analyze the FSO systems performance under fog conditions and pointing errors in terms of outage probability. We then study the impact of several effective communication mitigation techniques that can improve the system performance including multi-hop, transmit laser selection (TLS) and hybrid RF/FSO transmission. Closed-form expressions for the outage probability are derived and practical and comprehensive numerical examples are suggested to assess the obtained results. We found that the FSO system has limited performance that prevents applying FSO in wireless microcells that have a 500 m minimum cell radius. The performance degrades more when pointing errors appear. Increasing the transmitted power can improve the performance under light to moderate fog. However, under thick and dense fog the improvement is negligible. Using mitigation techniques can play a major role in improving the range and outage probability.

Outage Probability Analysis of FSO Links over Foggy Channel

KAUST Repository

Esmail, Maged Abdullah; Fathallah, Habib; Alouini, Mohamed-Slim

2017-01-01

Outdoor Free space optic (FSO) communication systems are sensitive to atmospheric impairments such as turbulence and fog, in addition to being subject to pointing errors. Fog is particularly severe because it induces an attenuation that may vary from few dBs up to few hundreds of dBs per kilometer. Pointing errors also distort the link alignment and cause signal fading. In this paper, we investigate and analyze the FSO systems performance under fog conditions and pointing errors in terms of outage probability. We then study the impact of several effective communication mitigation techniques that can improve the system performance including multi-hop, transmit laser selection (TLS) and hybrid RF/FSO transmission. Closed-form expressions for the outage probability are derived and practical and comprehensive numerical examples are suggested to assess the obtained results. We found that the FSO system has limited performance that prevents applying FSO in wireless microcells that have a 500 m minimum cell radius. The performance degrades more when pointing errors appear. Increasing the transmitted power can improve the performance under light to moderate fog. However, under thick and dense fog the improvement is negligible. Using mitigation techniques can play a major role in improving the range and outage probability.

On the Outage Performance of Full-Duplex Selective Decode-and-Forward Relaying

KAUST Repository

Khafagy, Mohammad Galal; Ismail, Amr; Alouini, Mohamed-Slim; Aissa, Sonia

2013-01-01

expression for the end-to-end outage probability that captures their joint effect. With the derived expression in hand, we propose a relay transmit power optimization scheme that only requires the relay knowledge of channel statistics. Finally, we corroborate our analysis with simulations.

Residential outage cost estimation: Hong Kong

International Nuclear Information System (INIS)

Woo, C.K.; Ho, T.; Shiu, A.; Cheng, Y.S.; Horowitz, I.; Wang, J.

2014-01-01

Hong Kong has almost perfect electricity reliability, the result of substantial investments ultimately financed by electricity consumers who may be willing to accept lower reliability in exchange for lower bills. But consumers with high outage costs are likely to reject the reliability reduction. Our ordered-logit regression analysis of the responses by 1876 households to a telephone survey conducted in June 2013 indicates that Hong Kong residents exhibit a statistically-significant preference for their existing service reliability and rate. Moreover, the average residential cost estimate for a 1-h outage is US$45 (HK$350), topping the estimates reported in 10 of the 11 studies published in the last 10 years. The policy implication is that absent additional compelling evidence, Hong Kong should not reduce its service reliability. - Highlights: • Use a contingent valuation survey to obtain residential preferences for reliability. • Use an ordered logit analysis to estimate Hong Kong's residential outage costs. • Find high outage cost estimates that imply high reliability requirements. • Conclude that sans new evidence, Hong Kong should not reduce its reliability

Development and demonstration of techniques for reducing occupational radiation doses during refueling outages. Tasks 7A/7B. Advanced outage management and radiation exposure control

International Nuclear Information System (INIS)

1985-03-01

Objectives of Tasks 7A and 7B were to develop and demonstrate computer based systems to assist plant management and staff in utilizing information more effectively to reduce occupational exposures received as a result of refueling outages, and to shorten the duration of the outage. The Advanced Outage Management (AOM) Tool (Task 7A) is an automated outage planning system specifically designed to meet the needs of nuclear plant outage management. The primary objective of the AOM tool is to provide a computerized system that can manipulate the information typically associated with outage planning and scheduling to furnish reports and schedules that more accurately project the future course of the outage. The Radiation Exposure Control (REC) Tool (Task 7B) is a computerized personnel radiation exposure accounting and management system designed to enable nuclear plant management to project and monitor total personnel radiation exposure on a real-time basis. The two systems were designed to operate on the same computer system and interface through a common database that enables information sharing between plant organizations not typically interfaced. This interfacing provides outage planners with a means of incorporating occupational radiation exposure as a factor for making decisions on the course of an outage

A Stackelberg Game Approach for Energy Outage-Aware Power Distribution of an Off-Grid Base Station over Multiple Retailers

Directory of Open Access Journals (Sweden)

Seung Hyun Jeon

2018-03-01

Full Text Available This paper investigates the problem of power distribution for an off-grid base station (BS that operates sustainably without an electrical grid. We consider that multiple retailers with heterogeneous renewable energy sources (RESs compete to maximize their revenues by individually setting the unit power price. Energy outages (EOs, which cause the power supply to fall below that which is sufficient for ensuring the traffic arrival rate required for the off-grid BS, critically affect the users’ service quality. To minimize EOs and operational expenditure (OPEX, the off-grid BS manages the power supply by reacting to the retailers’ pricing decisions. We analyze the economic benefits of power distribution to the off-grid BS from the perspective of the retailers’ pricing competition, by designing a hierarchical decision-making scheme as a multi-leader single-follower Stackelberg game. We derive a closed form expression for the optimal behavior of the off-grid BS and retailers, based on well-designed utility functions. Finally, numerical results demonstrate the proposed solution with its practical convergence time.

The process of NPP refuelling outage analysis and follow-up

International Nuclear Information System (INIS)

Nemec, T.; Savli, S.; Cernilogar Radez, M.; Persic, A.; Pecek, V.; Stritar, A.

2007-01-01

Following the outages in 2004 and 2006, the Slovenian Nuclear Safety Administration (SNSA) has started with the practice of independent outage analysis in a form of an internal report. It includes a comparison of performed activities against the planned time schedule of activities, evaluation of design modifications implementation and analysis of significant events. The main result of the outage analysis is a list of recommendations and some open issues that have been identified. These findings are the basis for development of an action plan for SNSA activities until the next outage, aimed at eliminating deficiencies found out during the outage and further improving outage activities. The established system of outage supervision together with the final analysis and long term action plan represents an effective continuous safety supervision process, by which the regulatory body independently contributes to the higher level of safety culture both at the licensee and among its own staff. (author)

Improving nuclear utility generation capacity, understanding the sources of forced outage and learning how to prevent them

International Nuclear Information System (INIS)

Brodeur, D.L.; Todreas, N.E.; Angus, V.T.

1998-01-01

MIT and PECO Energy have completed a detailed examination of the sources of forced outages at the Limerick Generating Station (LGS) Boiling Water Reactor Class IV (BWR IV) site over a five year period and contrasted that information to similar BWR IV utilities in the United States over the same period. Each forced outage was attributed to one system and assigned causal codes of equipment versus human factors and failure attributes such as weak design, poor craftsmanship, and worn parts. It was found that fifty four percent of the lost power at LGS was the result of Balance of Plant failures. Industry wide data identifies fifty nine percent of the lost power as attributed to Balance of Plant failures. Balance of Plant systems are those systems not included in the primary and safety related system category. Considering failure causal factors, forty six percent of the lost power at the utility under study was the result of equipment factors such as weak design or worn parts. Significantly, the study showed a high variance between those systems which caused significant forced outage at the two sister LGS units. This demonstrated the infrequent nature of plant forced outages within a given system. This was supported by the observation that dominant systems attributing to forced outage at LGS were not equally represented in industry data. It is suggested that for individual utilities to dramatically improve unit capability factors with regard to Balance of Plant systems, they must learn from industry wide experiences and develop cooperative means of exchanging lessons learned among similarly designed plants and systems. With the broad knowledge base of system failures, current designs must be frequently assessed and altered until each system poses an acceptable level of risk to generation capacity. (author)

Core design experience of WWER-440 reactors when they working on increased power level

International Nuclear Information System (INIS)

Adeev, V.; Panov, A.; Melenchuk, I.

2015-01-01

The Kola NPP continues commercial operation of 2nd generation fuel (FA-2) and trial operation of 3rd generation fuel (FA-3), which has a number of design features providing the best operational characteristics. This report gives the results of VVER-440 core operation with FA-2 and FA-3 with enrichment increased up to 4.87%, and at the power level uprated to 107% of nominal power level. Brief analysis of obtained data is carried out. Peculiarities and techniques of developing loading patterns with new types of nuclear fuel for operation at the uprated power level are reviewed. (authors)

Outage probability of distributed beamforming with co-channel interference

KAUST Repository

Yang, Liang

2012-03-01

In this letter, we consider a distributed beamforming scheme (DBF) in the presence of equal-power co-channel interferers for both amplify-and-forward and decode-and-forward relaying protocols over Rayleigh fading channels. We first derive outage probability expressions for the DBF systems. We then present a performance analysis for a scheme relying on source selection. Numerical results are finally presented to verify our analysis. © 2011 IEEE.

San Onofre - the evolution of outage management

International Nuclear Information System (INIS)

Slagle, K.A.

1993-01-01

With the addition of units 2 and 3 to San Onofre nuclear station in 1983 and 1984, it became evident that a separate group was needed to manage outages. Despite early establishment of a division to handle outages, it was a difficult journey to make the changes to achieve short outages. Early organizational emphasis was on developing an error-free operating environment and work culture. This is difficult for a relatively large organization at a three-unit site. The work processes and decision styles were designed to be very deliberate with many checks and balances. The organization leadership and accountability were focused in the traditional operations, maintenance, and engineering divisions. Later, our organization emphasis shifted to achieving engineering excellence. With a sound foundation of operating and engineering excellence, our organizational focus has turned to achieving quality outages. This means accomplishing the right work in a shorter duration and having the units run until the next refueling

Nuclear safety risk control in the outage of CANDU unit

International Nuclear Information System (INIS)

Wu Mingliang; Zheng Jianhua

2014-01-01

Nuclear fuel remains in the core during the outage of CANDU unit, but there are still nuclear safety risks such as reactor accidental criticality, fuel element failure due to inability to properly remove residual heat. Furthermore, these risks are aggravated by the weakening plant system configuration and multiple cross operations during the outage. This paper analyzes the phases where there are potential nuclear safety risks on the basis of the typical critical path arrangement of the outage of Qinshan NPP 3 and introduces a series of CANDU-specific risk control measures taken during the past plant outages to ensure nuclear safety during the unit outage. (authors)

MIT research reactor. Power uprate and utilization

Energy Technology Data Exchange (ETDEWEB)

Hu, Lin-Wen [Nuclear Reactor Laboratory, Massachusetts Inst. of Technology, Cambridge, MA (United States)

2012-03-15

The MIT Research Reactor (MITR) is a university research reactor located on MIT campus. and has a long history in supporting research and education. Recent accomplishments include a 20% power rate to 6 MW and expanding advanced materials fuel testing program. Another important ongoing initiative is the conversion to high density low enrichment uranium (LEU) monolithic U-Mo fuel, which will consist of a new fuel element design and power increase to 7 MW. (author)

Outage time reduction in GKN II without loss of safety

International Nuclear Information System (INIS)

Sturm, J.

1999-01-01

GKN II is a 1340 MWE 4-loop pressurised water reactor from Siemens KONVOI type, located in the south of Germany. It was originally connected to the grid at the end of 1988. Commercial operation under utility responsibility started at the second half of 1989. The first outage was performed in 1990. Beginning from this date, the outage duration was contiguously reduced from 33 days to 15 days in 1996. In 1998, two refueling and maintenance outages were performed, each with a duration of 7 days. Key planning factors to achieve these results are: A well adapted planning organisation with an outage manager and an outage planning team. An effective long term planning. This means the combination of work with a long duration every 4 or 8 years. No longlasting work in the years in between. Main work only on one safety train per year. Optimisation and standardisation of the shutdown and the startup sequence. The real change of reactor states have been modified, compared to the vendor recommendations. An tests are assigned to plant conditions, where they are most effective and are less time critical. Small modifications in the plant, mainly on the auxiliary systems, to speedup some sequences. Extreme detailed planning of maintenance and periodic tests. Each work/test can be found in a detailed schedule with a dedicated time widow. Optimized tools to perform the detailed planning and to implement the feedback of experience from former outages. Optimized tools for maintenance and handlings of heavy equipment on the critical path. Optimized tools to perform periodic tests. Key factors during outage are: Permanent control of the schedules with an updated 3-day program. Best and permanent information with this 3-day program of all people that are involved. Fast reaction on delays. Outage managers permanent on site. Gain in safety during shutdown states, with reduced outage duration: It has to be proven, that short outages don't lead to faster and less accurate work. It can be

Maintenance of nuclear power plants

International Nuclear Information System (INIS)

Lashgari, Farbod.

1995-01-01

This paper is about maintenance of nuclear power plants. In part one, the outage management of nuclear power plants has described. Meaning of the outage and objectives of outage management is given in introduction. The necessity of a long-term outage strategy is shown in chapter one. The main parts of an outage are as follows: Planning; Preparation; Execution, Each of them and also post-outage review have been explained in the followed chapters. Part two deals with technical details of main primary components of nuclear power plant type WWER. After an introduction about WWER reactors, in each chapter first the general and detailed description of main primary components has given and then their maintenance schedules and procedures. Chapter about reactor and steam generator is related to both types of WWER-440 and WWER-1000, but chapter about reactor coolant pump has specified to WWER-1000 to be more in details.(author)

A BWR 24-month cycle analysis using multicycle techniques

International Nuclear Information System (INIS)

Hartley, K.D.

1993-01-01

Boiling water reactor (BWR) fuel cycle design analyses have become increasingly challenging in the past several years. As utilities continue to seek improved capacity factors, reduced power generation costs, and reduced outage costs, longer cycle lengths and fuel design optimization become important considerations. Accurate multicycle analysis techniques are necessary to determine the viability of fuel designs and cycle operating strategies to meet reactor operating requirements, e.g., meet thermal and reactivity margin constraints, while minimizing overall fuel cycle costs. Siemens Power Corporation (SPC), Nuclear Division, has successfully employed multi-cycle analysis techniques with realistic rodded cycle depletions to demonstrate equilibrium fuel cycle performance in 24-month cycles. Analyses have been performed by a BWR/5 reactor, at both rated and uprated power conditions

On the Outage Performance of Full-Duplex Selective Decode-and-Forward Relaying

KAUST Repository

Khafagy, Mohammad Galal

2013-02-25

We evaluate the outage performance in a three-terminal full-duplex relay channel that adopts a selective decode-and-forward protocol, taking relay self-interference into account. Previous work focused on coverage extension scenarios where direct source-destination transmissions are neglected or considered as interference. In this work, we account for the relay self-interference, and exploit the cooperative diversity offered by the independently fading source/relay message replicas that arrive at the destination. We present an approximate, yet accurate, closed-form expression for the end-to-end outage probability that captures their joint effect. With the derived expression in hand, we propose a relay transmit power optimization scheme that only requires the relay knowledge of channel statistics. Finally, we corroborate our analysis with simulations.

Cell outage compensation in LTE networks: Algorithms and performance assessment

NARCIS (Netherlands)

Amirijoo, M.; Jorguseski, L.; Litjens, R.; Schmelz, L.C.

2011-01-01

Cell outage compensation is a self-healing function and as such part of the Self-Organising Networks concept for mobile wireless networks. It aims at mitigating the degradation of coverage, capacity and service quality caused by a cell or site level outage. Upon detection of such an outage, cell

Analysis of scrams and forced outages at boiling water reactors

International Nuclear Information System (INIS)

Earle, R.T.; Sullivan, W.P.; Miller, K.R.; Schwegman, W.J.

1980-07-01

This report documents the results of a study of scrams and forced outages at General Electric Boiling Water Reactors (BWRs) operating in the United States. This study was conducted for Sandia Laboratories under a Light Water Reactor Safety Program which it manages for the United States Department of Energy. Operating plant data were used to identify the causes of scrams and forced outages. Causes of scrams and forced outages have been summarized as a function of operating plant and plant age and also ranked according to the number of events per year, outage time per year, and outage time per event. From this ranking, identified potential improvement opportunities were evaluated to determine the associated benefits and impact on plant availability

Evaluation of the Planned Outage Durations in EU-APR

Energy Technology Data Exchange (ETDEWEB)

Jung, Byung Joon; Lee, Keun Sung [KHNP CRI, Daejeon (Korea, Republic of)

2016-10-15

EU-APR has been designed to comply with European Utility Requirements (EUR) and nuclear design requirements of the European countries. And it is modified and improved from its original design of APR1400. The whole duration varies depending on items for additional process. Refueling and regular maintenance outage is comprised of basic processes and Main turbine-generator outage includes dismantling inspection of main generator and high pressure turbine as a critical path in addition to basic processes. In-Service Inspection Outage includes Automatic ultrasonic inspection on the upper side/lower side of a nuclear reactor as a critical path in addition to basic processes. The planned outage durations of EU-APR are optimized according to the above results. And they are complied with EUR Requirement (EUR 2.2.7.2.2 B), respectively. In addition, outage duration can be reduced with improved operating technology and more maintenance friendly environment including betterment of filling, drain and ventilation.

Evaluation of the Planned Outage Durations in EU-APR

International Nuclear Information System (INIS)

Jung, Byung Joon; Lee, Keun Sung

2016-01-01

EU-APR has been designed to comply with European Utility Requirements (EUR) and nuclear design requirements of the European countries. And it is modified and improved from its original design of APR1400. The whole duration varies depending on items for additional process. Refueling and regular maintenance outage is comprised of basic processes and Main turbine-generator outage includes dismantling inspection of main generator and high pressure turbine as a critical path in addition to basic processes. In-Service Inspection Outage includes Automatic ultrasonic inspection on the upper side/lower side of a nuclear reactor as a critical path in addition to basic processes. The planned outage durations of EU-APR are optimized according to the above results. And they are complied with EUR Requirement (EUR 2.2.7.2.2 B), respectively. In addition, outage duration can be reduced with improved operating technology and more maintenance friendly environment including betterment of filling, drain and ventilation

Improving refueling outages through partnership

International Nuclear Information System (INIS)

Mercado, Angelo L.

2004-01-01

This paper describes an approach to reduce nuclear plant outage duration and cost through partnership. Partnership is defined as a long-term commitment between the utility and the vendor with the objective of achieving shared business goals by maximizing the effectiveness of each party's resources. The elements of an effective partnership are described. Specific examples are given as to how partnership has worked in the effective performance of refueling outages. To gain the full benefits of a partnership, both parties must agree to share information, define the scope early, communicate goals and expectations, and identify boundaries for technical ownership. (author)

Protective Controller against Cascade Outages with Selective Harmonic Compensation Function

Science.gov (United States)

Abramovich, B. N.; Kuznetsov, P. A.; Sychev, Yu A.

2018-05-01

The paper presents data on the power quality and development of protective devices for the power networks with distributed generation (DG).The research has shown that power quality requirements for DG networks differ from conventional ones. That is why main tendencies, protective equipment and filters should be modified. There isa developed algorithm for detection and prevention of cascade outages that can lead to the blackoutin DG networks and there was a proposed structural scheme for a new active power filter for selective harmonics compensation. Analysis of these theories and equipment led to the development of protective device that could monitor power balance and cut off non-important consumers. The last part of the article describes a microcontroller prototype developed for connection to the existing power station control center.

Study of electrical power facilities and measures for planned outages in Japanese hemodialysis clinics after the Great East Japan Earthquake.

Science.gov (United States)

Ishida, Kai; Sawa, Manami; Fujiwara, Kousaku; Hirose, Minoru; Tsuruta, Harukazu; Takeuchi, Akihiro; Ikeda, Noriaki

2013-02-01

The Great East Japan Earthquake on 11 March 2011 caused major damage in northeastern Japan. The Kanto region experienced a massive electrical power shortage in the summer of 2011. A questionnaire was submitted to 354 hemodialysis clinics in Kanagawa prefecture and the Tokyo metropolitan area, excluding isolated islands, and 176 responses were analyzed (49.7%). The questions included evaluation of the availability of a private electricity generator, countermeasures in case of a planned outage, awareness of saving electricity, and improvement of safety of medical devices or electrical facilities after the earthquake. Only 12% of the clinics had private electricity generators and many clinics had no plans to introduce this facility. However, 96% of the clinics had established countermeasures to deal with a planned outage. Many clinics planned to provide dialysis on a different day or at a different time. All clinics had tried hard to establish procedures to save electricity in the summer of 2011, and 84% of the clinics had reconsidered and improved the safety of medical devices or electricity facilities after the earthquake. These results show that the awareness of crisis management was greatly improved in the wake of the earthquake. © 2012 The Authors. Therapeutic Apheresis and Dialysis © 2012 International Society for Apheresis.

Methodology if inspections to carry out the nuclear outages model

International Nuclear Information System (INIS)

Aycart, J.; Mortenson, S.; Fourquet, J. M.

2005-01-01

Before the nuclear generation industry was deregulated in the United States, refueling and maintenance outages in nuclear power plants usually lasted orotund 100 days. After deregulation took effect, improved capability factors and performances became more important. As a result, it became essential to reduce the critical path time during the outage, which meant that activities that had typically been done in series had to be executed in parallel. The new outage model required the development of new tools and new processes, The 360-degree platform developed by GE Energy has made it possible to execute multiple activities in parallel. Various in-vessel visual inspection (IVVI) equipments can now simultaneously perform inspections on the pressurized reactor vessel (RPV) components. The larger number of inspection equipments in turn results in a larger volume of data, with the risk of increasing the time needed for examining them and postponing the end of the analysis phase, which is critical for the outage. To decrease data analysis times, the IVVI Digitalisation process has been development. With this process, the IVVI data are sent via a high-speed transmission line to a site outside the Plant called Center of Excellence (COE), where a team of Level III experts is in charge of analyzing them. The tools for the different product lines are being developed to interfere with each other as little as possible, thus minimizing the impact of the critical path on plant refueling activities. Methods are also being developed to increase the intervals between inspection. In accordance with the guidelines of the Boiling Water Reactor Vessel and Internals project (BWRVIP), the intervals between inspections are typically longer if ultrasound volumetric inspections are performed than if the scope is limited to IVVI. (Author)

Approach to shortening duration of nuclear plant refueling outage

Energy Technology Data Exchange (ETDEWEB)

Takahashi, Yoshiharu; Nakanishi, Tooru [Mitsubishi Heavy Industries Ltd., Kobe (Japan). Kobe Shipyard and Machinery Works; Yoshihara, Seiichi; Kanbara, Masayuki; Yamanaka, Misao; Shimizu, Takeshi

1998-07-01

This paper summarizes the mission role of the MHI in-house project team for a shorter outage duration for PWR plants operating in Japan and its results. The major tasks of project team are benchmarking to develop outage performance goals, and develop recommendation packages for outage enhancement covering field procedures and tooling betterment. An optimization study for maintenance tasks was also carried out. This paper highlights the results of efforts the activities of the project team. (author)

Evaluation of allowed outage time using PRA results

International Nuclear Information System (INIS)

Johanson, G.

1985-01-01

In a probabilistic risk assessment (PRA) different measures of risk importance can be established. These measures can be used as a basis for further evaluation and determination of allowed outage time for specific components, within safety systems of a nuclear power plant. In order to optimize the allowed outage time (AOT) stipulated in the plant's Technical Specification it is necessary to create a methodology which could incorporate existing PRA data into a quantitative extrapolation. In order to evaluate the plant risk status due to AOT in a quantitative manner, the risk achievement worth is utilized. Risk achievement worth is defined as follows: to measure the worth of a feature, in achieving the present risk, one approach is to remove the feature and then determine how much the risk has increased. Thus, the risk achievement worth is formally defined to be the increase in risk if the feature were assumed not be there or to be failed. Another parameter of interest for this analysis is the shutdown risk increase. The shutdown risk achievement worth must be incorporated into the accident sequence risk achievement worth to arrive at an optimal set of plant specific AOTs

Elimination of maintenance outage and cost reduction by development of outage-free maintenance techniques

International Nuclear Information System (INIS)

Jakabe, Hideo; Maruyama, Yoshinaga

1996-01-01

The development program of KEPCO on outage-free maintenance techniques for distribution line work since 1984 is overviewed. It has succeeded in eliminating maintenance outages since 1989. The original aim was to improve customer satisfaction. However, in all, four benefits were realised through the development. These are cost reduction, securing of worker safety, improvement of customer service, and advancement of distribution techniques and morale in KEPCO. The introduction of robotic techniques for maintenance work and manipulator techniques for repair work is planned for further modernization. These new techniques are helping in both work safety and work efficiency improvement. Cost reduction and advancement of distribution line work techniques is also considered. (R.P.)

Design Concepts for an Outage Control Center Information Dashboard

International Nuclear Information System (INIS)

Hugo, Jacques Victor; St Germain, Shawn Walter; Thompson, Cheradan Jo; Whitesides, McKenzie Jo; Farris, Ronald Keith

2015-01-01

The nuclear industry, and the business world in general, is facing a rapidly increasing amount of data to be dealt with on a daily basis. In the last two decades, the steady improvement of data storage devices and means to create and collect data along the way influenced the manner in which we deal with information. Most data is still stored without filtering and refinement for later use. Many functions at a nuclear power plant generate vast amounts of data, with scheduled and unscheduled outages being a prime example of a source of some of the most complex data sets at the plant. To make matters worse, modern information and communications technology is making it possible to collect and store data faster than our ability to use it for making decisions. However, in most applications, especially outages, raw data has no value in itself; instead, managers, engineers and other specialists want to extract the information contained in it. The complexity and sheer volume of data could lead to information overload, resulting in getting lost in data that may be irrelevant to the task at hand, processed in an inappropriate way, or presented in an ineffective way. To prevent information overload, many data sources are ignored so production opportunities are lost because utilities lack the ability to deal with the enormous data volumes properly. Decision-makers are often confronted with large amounts of disparate, conflicting and dynamic information, which are available from multiple heterogeneous sources. Information and communication technologies alone will not solve this problem. Utilities need effective methods to exploit and use the hidden opportunities and knowledge residing in unexplored data resources. Superior performance before, during and after outages depends upon the right information being available at the right time to the right people. Acquisition of raw data is the easy part; instead, it is the ability to use advanced analytical, data processing and data

Design Concepts for an Outage Control Center Information Dashboard

Energy Technology Data Exchange (ETDEWEB)

Hugo, Jacques Victor [Idaho National Lab. (INL), Idaho Falls, ID (United States); St Germain, Shawn Walter [Idaho National Lab. (INL), Idaho Falls, ID (United States); Thompson, Cheradan Jo [Idaho National Lab. (INL), Idaho Falls, ID (United States); Whitesides, McKenzie Jo [Idaho National Lab. (INL), Idaho Falls, ID (United States); Farris, Ronald Keith [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2015-12-01

The nuclear industry, and the business world in general, is facing a rapidly increasing amount of data to be dealt with on a daily basis. In the last two decades, the steady improvement of data storage devices and means to create and collect data along the way influenced the manner in which we deal with information. Most data is still stored without filtering and refinement for later use. Many functions at a nuclear power plant generate vast amounts of data, with scheduled and unscheduled outages being a prime example of a source of some of the most complex data sets at the plant. To make matters worse, modern information and communications technology is making it possible to collect and store data faster than our ability to use it for making decisions. However, in most applications, especially outages, raw data has no value in itself; instead, managers, engineers and other specialists want to extract the information contained in it. The complexity and sheer volume of data could lead to information overload, resulting in getting lost in data that may be irrelevant to the task at hand, processed in an inappropriate way, or presented in an ineffective way. To prevent information overload, many data sources are ignored so production opportunities are lost because utilities lack the ability to deal with the enormous data volumes properly. Decision-makers are often confronted with large amounts of disparate, conflicting and dynamic information, which are available from multiple heterogeneous sources. Information and communication technologies alone will not solve this problem. Utilities need effective methods to exploit and use the hidden opportunities and knowledge residing in unexplored data resources. Superior performance before, during and after outages depends upon the right information being available at the right time to the right people. Acquisition of raw data is the easy part; instead, it is the ability to use advanced analytical, data processing and data

Olkiluoto 1 and 2 - Plant efficiency improvement and lifetime extension-project (PELE) implemented during outages 2010 and 2011

Energy Technology Data Exchange (ETDEWEB)

Kosonen, M.; Hakola, M. [Teollisuuden Voima Oyj, F- 27160 Eurajoki (Finland)

2012-07-01

Teollisuuden Voima Oyj (TVO) is a non-listed public company founded in 1969 to produce electricity for its stakeholders. TVO is the operator of the Olkiluoto nuclear power plant. TVO follows the principle of continuous improvement in the operation and maintenance of the Olkiluoto plant units. The PELE project (Plant Efficiency Improvement and Lifetime Extension), mainly completed during the annual outages in 2010 and 2011, and forms one part of the systematic development of Olkiluoto units. TVO maintains a long-term development program that aims at systematically modernizing the plant unit systems and equipment based on the latest technology. According to the program, the Olkiluoto 1 and Olkiluoto 2 plant units are constantly renovated with the intention of keeping them safe and reliable, The aim of the modernization projects is to improve the safety, reliability, and performance of the plant units. PELE project at Olkiluoto 1 was done in 2010 and at Olkiluoto 2 in 2011. The outage length of Olkiluoto 1 was 26 d 12 h 4 min and Olkiluoto 2 outage length was 28 d 23 h 46 min. (Normal service-outage is about 14 days including refueling and refueling-outage length is about seven days. See figure 1) The PELE project consisted of several single projects collected into one for coordinated project management. Some of the main projects were as follows: - Low pressure turbines: rotor, stator vane, casing and turbine instrumentation replacement. - Replacement of Condenser Cooling Water (later called seawater pumps) pumps - Replacement of inner isolation valves on the main steam lines. - Generator and the generator cooling system replacement. - Low voltage switchgear replacement. This project will continue during future outages. PELE was a success. 100 TVO employees and 1500 subcontractor employees participated in the project. The execution of the PELE projects went extremely well during the outages. The replacement of the low pressure turbines and seawater pumps improved the

Olkiluoto 1 and 2 - Plant efficiency improvement and lifetime extension-project (PELE) implemented during outages 2010 and 2011

International Nuclear Information System (INIS)

Kosonen, M.; Hakola, M.

2012-01-01

Teollisuuden Voima Oyj (TVO) is a non-listed public company founded in 1969 to produce electricity for its stakeholders. TVO is the operator of the Olkiluoto nuclear power plant. TVO follows the principle of continuous improvement in the operation and maintenance of the Olkiluoto plant units. The PELE project (Plant Efficiency Improvement and Lifetime Extension), mainly completed during the annual outages in 2010 and 2011, and forms one part of the systematic development of Olkiluoto units. TVO maintains a long-term development program that aims at systematically modernizing the plant unit systems and equipment based on the latest technology. According to the program, the Olkiluoto 1 and Olkiluoto 2 plant units are constantly renovated with the intention of keeping them safe and reliable, The aim of the modernization projects is to improve the safety, reliability, and performance of the plant units. PELE project at Olkiluoto 1 was done in 2010 and at Olkiluoto 2 in 2011. The outage length of Olkiluoto 1 was 26 d 12 h 4 min and Olkiluoto 2 outage length was 28 d 23 h 46 min. (Normal service-outage is about 14 days including refueling and refueling-outage length is about seven days. See figure 1) The PELE project consisted of several single projects collected into one for coordinated project management. Some of the main projects were as follows: - Low pressure turbines: rotor, stator vane, casing and turbine instrumentation replacement. - Replacement of Condenser Cooling Water (later called seawater pumps) pumps - Replacement of inner isolation valves on the main steam lines. - Generator and the generator cooling system replacement. - Low voltage switchgear replacement. This project will continue during future outages. PELE was a success. 100 TVO employees and 1500 subcontractor employees participated in the project. The execution of the PELE projects went extremely well during the outages. The replacement of the low pressure turbines and seawater pumps improved the

Reactor outage schedule (tentative)

Energy Technology Data Exchange (ETDEWEB)

Walton, R.P.

1969-11-01

This single page document is the November 1, 1969 reactor refueling outage schedule for the Hanford Production Reactor. It also contains data on the amounts and types of fuels to be loaded and relocated in the production reactor.

Reactor outage schedule (tentative)

Energy Technology Data Exchange (ETDEWEB)

Walton, R.P.

1969-10-01

This single page document is the October 1, 1969 reactor refueling outage schedule for the Hanford Production Reactor. It also contains data on the amounts and types of fuels to be loaded and relocated in the Production Reactor.

Reactor outage schedule (tentative)

Energy Technology Data Exchange (ETDEWEB)

Walton, R.P.

1969-10-15

This single page document is the October 15, 1969 reactor refueling outage schedule for the Hanford Production Reactor. It also contains data on the amounts and types of fuels to be loaded and relocated in the Production Reactor.

Reactor outage schedule (tentative)

Energy Technology Data Exchange (ETDEWEB)

Walton, R.P.

1969-09-15

This single page document is the September 15, 1969 reactor refueling outage schedule for the Hanford Production Reactor. It also contains data on the amounts and types of fuels to be loaded and relocated in the Production Reactor.

Reactor outage schedule (tentative)

Energy Technology Data Exchange (ETDEWEB)

Walton, R.P.

1969-12-15

This single page document is the December 16, 1969 reactor refueling outage schedule for the Hanford Production Reactor. It also contains data on the amounts and types of fuels to be loaded and relocated in the Production reactor.

Reactor outage schedule (tentative)

Energy Technology Data Exchange (ETDEWEB)

Walton, R.P.

1969-12-01

This single page document is the December 1, 1969 reactor refueling outage schedule for the Hanford Production Reactor. It also contains data on the amounts and types of fuels to be loaded and relocated in the Production reactor.

Integrated use of Primavera and ORAM codes in outage 1999 at NPP Krsko

International Nuclear Information System (INIS)

Krajnc, J.; Skaler, F.; Basic, I.; Kocnar, R.

1999-01-01

The paper deals with the following postulated main goals of outage scheduling with Primavera tool at Krsko NPP: planning and controlling of resources (people, equipment, locations, sources), controlling the safety aspects of an outage and assuring defense-in-depth philosophy (through integrated safety assessment by ORAM code), diversity use of the plan during preparations period and outage progress (MCB, work leaders, management, planning Dept., subcontractors, support, etc.), allowing for optimization of outage duration. A snapshot in Primavera of what actually happened in outage 1999, lessons learned and a new work template is the scope of the next year outage.(author)

Observations and insights from low power and shutdown studies: Grand Gulf Nuclear Power Plant during POS 5 of a refueling outage

International Nuclear Information System (INIS)

Whitehead, D.W.; Brown, T.D.; Forester, J.A.

1995-04-01

With the recent completion of the documentation of the results from the Grand Gulf Nuclear Power Plant Low Power and Shutdown (LP and S) project funded by the US Nuclear Regulatory Commission (NRC), detailed probabilistic risk assessment (PRA) information from a boiling water reactor (BWR) for a specific time period in LP and S conditions became available for examination. This report contains observations and insights extracted from an examination of: (1) results in the LP and S documentation; (2) the specific models and assumptions used in the LP and S analyses; (3) selected results from the full-power analysis; (4) the experience of the analysts who performed the original LP and S study; and (5) results from sensitivity calculations performed as part of this project to help determine the impact that model assumptions and data values had on the results from the original LP and S analysis. Specifically, this study makes observations on and develops insights from the estimates of core damage frequency and aggregate risk (early fatalities and total latent cancer fatalities) associated with operations during plant operational state (POS) 5 (i.e., basically cold shutdown as defined by Technical Specifications) during a refueling outage for traditional internal events. A discussion of similarities and differences between full power accidents and accidents during LP and S conditions is provided. As part of this discussion, core damage frequency and risks results are presented on a per hour and per calendar year basis, allowing alternative perspectives on both the core damage frequency and risk associated with these two operational states

Outage probability analysis of a secondary user in an underlay dual hop cognitive amplify and forward relay network

Directory of Open Access Journals (Sweden)

Kiran Chandra

2016-09-01

Full Text Available This paper presents the performance evaluation of a secondary user (SU in an underlay cognitive dual-hop relaying system considering instantaneous as well as average channel information of the interfering links (from the secondary source and relay to the primary receiver and the data link from the secondary source to relay, to calculate transmit power and amplifying gain of secondary system. Comparison of above mentioned cases is done for two different scenarios – with direct path and without direct path. We evaluate the performance considering two different diversity techniques namely as selection combining (SC and maximum ratio combining (MRC. The effect of different fading channels (Rayleigh and Nakagami on the outage performance of the SU for the two diversity techniques is also shown. The outage probability of the SU is reduced when the diversity techniques are used (with direct path as compared to the outage probability of SU without direct path. We find that the outage performance is better for instantaneous channel information as compared to average channel information for the links. We observe that MRC provides better performance than SC. Furthermore, this work shows that the outage performance of the SU has been improved when the Nakagami fading channel (m = 2 is considered instead of Rayleigh fading channel.

Saving doses by outage planning strategy and architectural arrangements

International Nuclear Information System (INIS)

Wahlstroem, B.

1993-01-01

All radiation doses come out as a result of dose rate and exposure time, and the main part of the occupational exposure is caused during outages. While every reasonable attempt should be made to lower the dose rates, the other factor, the exposure time, may not be forgotten. The paper presents possible ways of saving man-hours in the controlled zone by outage planning strategy. And every saved man-hour means a saved radiation dose. At Loviisa NPS also some special architectural arrangements contribute to shortening the outage time, thus saving doses

Line outage contingency analysis including the system islanding ...

African Journals Online (AJOL)

The optimally ordered sparse [Bʹ], [Bʺ] matrices for the integrated system are used for load flow analysis to determine modified values of voltage phase angles [d] and bus voltages [V] to determine the over loading effect on the remaining lines due to outage of a selected line outage contingency. In case of over loading in ...

Application of 4-Face Fuel Visual Inspection System during Outage in Nuclear Power Plant

International Nuclear Information System (INIS)

Shin, J. C.; Kim, J. I.; Choi, C. B.; Kim, Y. C.; Kang, C. B.

2008-01-01

Recently, as a measure to reduce an outage duration in nuclear power plants (NPPs), a four-face fuel visual inspection system (4-FFVIS) built in 4 cameras was introduced by Ahlberg Electronics, Sweden. The 4- FFVIS is used to inspect the external appearance of irradiated fuel assemblies in order to confirm their integrity against mechanical defects and foreign materials. Until now, however, a typical one-face fuel inspection system(1-FFVIS) has been world-widely utilized in NPPs. The 1-FFVIS requires four turns with 90 degree to inspect every face of the fuel assembly, causing a relatively long inspecting time. But the 4- FFVIS allow us to inspect every face of the fuel assembly at the same time. The inspection time with the 4-FFVIS may be less than two minutes per fuel assembly, whereas that with the 1-FFVIS is about six minutes per fuel assembly. In viewpoint of this merit, the 4-FFVIS is expected to be world-widely used in the near future. In this paper, the technical requirements necessary to develop the 4-FFVIS as well as some improvements to complement the current 4-FFVIS are described

To minimized power outage by the application of 'RTV' (room temperature vulcanizing) silicon on high voltage porcelain insulators in Pakistan

International Nuclear Information System (INIS)

Hafiz Tehzeeb ul Hassan

2003-01-01

In Pakistan power network comprises of 500KV, 220KV, 132KV, 66KV and 33KV transmission lines and 11KV power distribution systems. Number of insulators are used in connected units in the shape of strings with transmission line as per insulation requirements with proper design according to the various kinds of pollution stresses. The transmission lines are passing from or near polluted areas and very dusty plains of Punjab and Sindh provinces. Practices are being used in these transmission lines for removal of accumulated contamination of insulators by periodic cleaning twice a year or de-energized transmission lines. Even then discontinuation of supply takes place in the polluted areas in foggy weather. Special technique of using water repellent (Room Temperature Vulcanizing) silicone coating/paint has been introduced on high voltage disc Insulators to minimize the outage in power net work in Pakistan. Especially in high pollution areas near chemical factories and near brick kilns etc comparison study of coated and uncoated disc Insulators have been carried out by ESDD (Equal Salt Deposit Density) measurement in salt fog chamber. (author)

Optimal utilization of outages. The tasks of the OEM and/or service provider

International Nuclear Information System (INIS)

Jakobs, Norbert; Grauf, Eberhard

1998-01-01

The deregulation of Europe's power market on January 1, 1999 will force many electric utilities and especially nuclear power plant operators to introduce extensive cost-cutting measures in order that they can hold their own in the new competitive environment. Existing plants basically have three potential ways of reducing their power generating costs: by increasing availability, reducing fuel costs and cutting back operating costs. Optimizing plant outages provides considerable potential for raising plant availability but can also lower operating costs by reducing expenditure on maintenance. In order to optimize an outage in terms of performance time and cost, there are a number of starting points based on certain key factors: organization, planning, logistics, performance monitoring, plant and equipment enhancements as well as personnel motivation. To reach this goal it is necessary for the original equipment manufacturer (OEM) and/or service provider to be involved in these activities to a much greater extent than before and for a closer form of partnership to be established with the consumer. For it is only within a team having a common set of goals that the successes of the past have been able to be achieved and new tasks can be efficiently handled in the future. (author)

Outage and ser performance of an opportunistic multi-user underlay cognitive network

KAUST Repository

Khan, Fahd Ahmed

2012-10-01

Consider a multi-user underlay cognitive network where multiple cognitive users concurrently share the spectrum with a primary network and a single secondary user is selected for transmission. The channel is assumed to have independent but not identical Nakagami-m fading. Closed form expressions for the outage performance and the symbol-error-rate performance of the opportunistic multi-user secondary network are derived when a peak interference power constraint is imposed on the secondary network in addition to the limited peak transmit power of each secondary user. © 2012 IEEE.

Theoretical and Experimental Investigations of Highly Uprated Diesel Engine with Temperature Regulator of Supercharging Air

Directory of Open Access Journals (Sweden)

G. A. Vershina

2005-01-01

Full Text Available Mathematical model of a highly uprated diesel engine with turbo-supercharging and intercooler of supercharging air is given in die paper. Theoretical study based on the model has made it possible to design and test an intercooler with a temperature regulator of supercharging air. Test results prove efficiency of temperature regulation of supercharging air in operation of an engine at low loads with excess air factor more than 3.2.

Peach Bottom Atomic Power Station, Units 2 and 3. Annual operating report: January--December 1976

International Nuclear Information System (INIS)

1977-01-01

Unit 2 experienced 11 forced outages, 5 power reductions, and one major refueling outage which lasted about 3 months during which time the feedwater spargers were replaced. Net electrical power generated was 5,569,633 MWH with the generator on line 5,998 hrs. Unit 3 experienced 17 forced outages, 11 power reductions and 2 major outages. The first refueling outage began 12/24/77. Net electrical power generated was 6,049,644 MWH with the unit on line 6,829 hrs. Information is presented concerning operations, personnel exposures, radioactive releases, maintenance, and irradiated fuel examination

Reliabilty worth: Development of a relationship with outage magnitude, duration and frequency

International Nuclear Information System (INIS)

Turner, F.P.P.; Katrichak, A.M.; Dwyer, A.; Edwards, D.; Ibrahim, A.

1994-01-01

British Columbia Hydro's Worth Project Team was founded to determine values for reliability for reference in evaluation of investment and operating decisions. Work to date has produced key preliminary values for specific outages and concepts for the shape of the relationship between value and these determinates of reliability worth, frequency, magnitude and duration. These values and concepts are described. The values are developed through an iterative, trial and refinement approach. The approach incorporates direct input from customers, common sense and judgement, and micro- and macro-economic concepts. Reliability worth values for reduced or prevented outages are presented for residential, commercial, small industrial and mixed sectors and various outage durations. Reliability worth values were obtained through customer surveys. Limitations of the reliability worth value are numerous and are listed. Study of cost vs magnitude of interruption using microeconomic models has shown that costly system improvements to reduce the possibility of widespread outages may not be justified. The case of exceptionally large area outages (blackouts) is examined. The cost vs frequency relationship was examined in terms of the economic concept of utility or satisfaction. Different loss/frequency characteristics are demonstrated for different customer classes. Customer value for reduced outage duration is expressed in a curve with flatter slope than that for eliminated outages. 2 refs., 6 figs

The Role of Occupational Health and Safety in Complex Outage Services to NPPs

International Nuclear Information System (INIS)

Rozman, A.; Androjna, A.

2010-01-01

Meeting outage schedules in NPPs which are increasingly demanding, apart from all other aspects, introduces a new perspective on occupational health and safety (OHS). Not only is the OHS a constituent part of a plant's overall outage management, it above all dictates paramount objectives to outage service providers. The paper reviews the impacts of reductions of outage durations on OHS and presents related experience of the leading Slovenian outage services provider, NUMIP d.o.o. over the last ten years. The company is now getting prepared for its 12th outage at Krsko NPP in 2010, and has not have recorded a major injury so far, even though these projects engaged over 450 people at a time on-site. To achieve such results, a lot of emphasis is being put onto OHS management prior to and during outages. A certified OHSAS 18001 system has been established and implemented to further support preparation and execution of NUMIP's outage activities at Krsko NPP, and also for other projects. An effective continuous improvement system is built into the project, providing for implementation of lessons learned from domestic and foreign plants. To illustrate the topic in more detail, a case on a Seismic protection of polar crane project is presented. It took place in the 2009 Outage and has certainly been one of the most demanding projects from the OHS point of view for NUMIP so far. The paper aims at contributing to a better understanding of the role of effective management of OHS on the side of a service provider, and, consequently, in the overall outage success of a plant.(author).

Consequences of long-term power outages and high electricity prices lasting for months; Konsekvenser av langvarige stroemutfall og hoeye kraftpriser i flere maaneder

Energy Technology Data Exchange (ETDEWEB)

NONE

2005-07-01

Several areas in the world have experienced electricity outages for longer periods of time, but the consequences of these are sparsely documented. There is a need for further analysis of the socioeconomic consequences of the outages. In addition to KILE (Quality adjusted revenue framework for un supplied energy) costs one has to take into account that the costs often increase proportionally with the durance of the outage, and that KILE tariffs do not reflect lost consumer's surplus for products that are not produced during an outage. A good example is the public underground transport, where the company's economical loss can be significantly smaller than the loss of utility value for the travellers. If the authorities act with reasonability it is difficult to see that periods with very high prices represent a big problem. The most important problems are related to diffused effects, especially for households with a weak economy. These problems can be solved with improved contractual forms (price guarantees) or by transfers to the households, without weakening the incentives for electricity economising (ml)

Thermal Analysis for Environmental Qualification of Kori Nuclear power plant unit 3 and 4

International Nuclear Information System (INIS)

Seo, Kwi Hyun; Byun, Choong Sup; Song, Dong Soo

2006-01-01

This paper shows the temperature profiles of safety related electrical equipment exposed to MSLB inside containment. It must be demonstrated that the LOCA qualification conditions exceed or are equivalent to the maximum calculated MSLB conditions. COPATTA as Bechtel's vendor code is used for the containment pressure and temperature prediction in power uprating project for Kori 3,4 and Yonggwang 1,2 nuclear power plants(NPPs). However, CONTEMPT-LT/028 is used for calculating the containment pressure and temperatures in equipment qualification project for the same NPPs. Power uprating code that is, COPATTA benchmarking study performed in six equipment at saturation temperature and surface temperature. Specially, thermal analysis carefully investigate that view point environmental qualification and NUREG- 0588 be mentioned in regard to safety-related heat sink it boundary condition or geometry information

Thermal Analysis for Environmental Qualification of Kori Nuclear power plant unit 3 and 4

Energy Technology Data Exchange (ETDEWEB)

Seo, Kwi Hyun [ENERGEO Inc., Sungnam (Korea, Republic of); Byun, Choong Sup; Song, Dong Soo [KEPRI, Taejon (Korea, Republic of)

2006-07-01

This paper shows the temperature profiles of safety related electrical equipment exposed to MSLB inside containment. It must be demonstrated that the LOCA qualification conditions exceed or are equivalent to the maximum calculated MSLB conditions. COPATTA as Bechtel's vendor code is used for the containment pressure and temperature prediction in power uprating project for Kori 3,4 and Yonggwang 1,2 nuclear power plants(NPPs). However, CONTEMPT-LT/028 is used for calculating the containment pressure and temperatures in equipment qualification project for the same NPPs. Power uprating code that is, COPATTA benchmarking study performed in six equipment at saturation temperature and surface temperature. Specially, thermal analysis carefully investigate that view point environmental qualification and NUREG- 0588 be mentioned in regard to safety-related heat sink it boundary condition or geometry information.

Outage Risk Assessment and Management (ORAM) thermal-hydraulics toolkit

International Nuclear Information System (INIS)

Denny, V.E.; Wassel, A.T.; Issacci, F.; Pal Kalra, S.

2004-01-01

A PC-based thermal-hydraulic toolkit for use in support of outage optimization, management and risk assessment has been developed. This mechanistic toolkit incorporates simple models of key thermal-hydraulic processes which occur during an outage, such as recovery from or mitigation of outage upsets; this includes heat-up of water pools following loss of shutdown cooling, inadvertent drain down of the RCS, boiloff of coolant inventory, heatup of the uncovered core, and reflux cooling. This paper provides a list of key toolkit elements, briefly describes the technical basis and presents illustrative results for RCS transient behavior during reflux cooling, peak clad temperatures for an uncovered core and RCS response to loss of shutdown cooling. (author)

Quantification of risk considering external events on the change of allowed outage time and the preventive maintenance during power operation

Energy Technology Data Exchange (ETDEWEB)

Kang, D. J.; Kim, K. Y.; Yang, J. E

2001-03-01

In this study, for the major safety systems of Ulchin Units 3/4, we quantify the risk on the change of AOT and the PM during power operation to identify the effects on the results of external events PSA when nuclear power plant changes such as allowed outage time are requested. The systems for which the risks on the change of allowed outage time are quantified are High Pressure Safety Injection System (HPSIS), Containment Spray System (CSS), and Emergency Diesel Generator (EDG). The systems for which the risks on the PM during power operation are Low Pressure Safety Injection System (LPSIS), CSS, EDG, Essential Service Water System (ESWS). Following conclusions can be obtained through this study: 1)The increase of core damage frequency ({delta}CDF) on the change of AOT and the conditional core damage probability (CCDP) on the on-line PM of each system are differently quantified according to the cases of considering only internal events or only external events. . 2)It is expected that the quantification of risk including internal and external events is advantageous for the licensee of NPP if the regulatory acceptance criteria for the technical specification changes are relatively set up. However, it is expected to be disadvantageous for the licensee if the acceptance criteria are absolutely set up. 3)It is expected that the conduction on the quantification of only a fire event is sufficient when the quantification of external events PSA model is required for the plant changes of Korea Standard NPPs. 4)It is expected that the quantification of the increase of core damage frequency and the incremental conditional core damage probability on technical specification changes are not needed if the quantification results of those considering only internal events are below regulatory acceptance criteria and the external events PSA results are not greatly affected by the system availability. However, it is expected that the quantification of risk considering external events

Quantification of risk considering external events on the change of allowed outage time and the preventive maintenance during power operation

International Nuclear Information System (INIS)

Kang, D. J.; Kim, K. Y.; Yang, J. E.

2001-03-01

In this study, for the major safety systems of Ulchin Units 3/4, we quantify the risk on the change of AOT and the PM during power operation to identify the effects on the results of external events PSA when nuclear power plant changes such as allowed outage time are requested. The systems for which the risks on the change of allowed outage time are quantified are High Pressure Safety Injection System (HPSIS), Containment Spray System (CSS), and Emergency Diesel Generator (EDG). The systems for which the risks on the PM during power operation are Low Pressure Safety Injection System (LPSIS), CSS, EDG, Essential Service Water System (ESWS). Following conclusions can be obtained through this study: 1)The increase of core damage frequency (ΔCDF) on the change of AOT and the conditional core damage probability (CCDP) on the on-line PM of each system are differently quantified according to the cases of considering only internal events or only external events. . 2)It is expected that the quantification of risk including internal and external events is advantageous for the licensee of NPP if the regulatory acceptance criteria for the technical specification changes are relatively set up. However, it is expected to be disadvantageous for the licensee if the acceptance criteria are absolutely set up. 3)It is expected that the conduction on the quantification of only a fire event is sufficient when the quantification of external events PSA model is required for the plant changes of Korea Standard NPPs. 4)It is expected that the quantification of the increase of core damage frequency and the incremental conditional core damage probability on technical specification changes are not needed if the quantification results of those considering only internal events are below regulatory acceptance criteria and the external events PSA results are not greatly affected by the system availability. However, it is expected that the quantification of risk considering external events on

Risk-based evaluation of allowed outage time and surveillance test interval extensions for nuclear power plants

International Nuclear Information System (INIS)

Gibelli, Sonia Maria Orlando

2008-03-01

The main goal of this work is, through the use of Probabilistic Safety Analysis (PSA), to evaluate Technical Specification (TS) Allowed Outage Times (AOT) and Surveillance Test Intervals (STI) extensions for Angra 1 nuclear power plant. PSA has been incorporated as an additional tool, required as part of NPP licensing process. The risk measure used in this work is the Core Damage Frequency (CDF), obtained from the Angra 1 PSA Level 1. AOT and STI extensions are calculated for the Safety Injection System (SIS), Service water System (SAS) and Auxiliary Feedwater System (AFS) through the use of SAPHIRE code. In order to compensate for the risk increase caused by the extensions, compensatory measures as test of redundant train prior to entering maintenance and staggered test strategy are proposed. Results have shown that the proposed AOT extensions are acceptable for the SIS and SAS with the implementation of compensatory measures. The proposed AOT extension is not acceptable for the AFS. The STI extensions are acceptable for all three systems. (author)

Improvement of availability of PWR nuclear plants through the reduction of the time required for refueling/maintenance outages, Phase 1. Final report

International Nuclear Information System (INIS)

Thompson, C.A.

1978-08-01

The objective of this project is to identify improvements in procedures and equipment which will reduce the time required for refueling/maintenance outages at PWR nuclear power plants. The outage of Commonwealth Edison Zion Station Unit 1 in March through May of 1976 was evaluated to identify those items which caused delays and those work activities that offer the potential for significant improvements toward reducing its overall duration. Thus, the plant's availability for power production would be increased. Revisions in procedures and some equipment modifications were implemented and evaluated during the Zion Unit 2 refueling/maintenance outage beginning in January 1977. Analysis of the observed data has identified benefits available through improved refueling equipment and also areas where additional new, innovative refueling, or refueling-related equipment should be beneficial. A number of specific design concepts are recommended as a result of Phase 1. In addition, a new master planning mechanism is described for implementation during subsequent planned outages at Zion Station. This final report describes the recommended conceptual designs and planning mechanism and assesses their impact upon future outages. Their effect on savings in refueling time, labor, and radiation exposure is discussed. The estimated economic payoff for these concepts was found to be of such significance that an additional phase of the program is warranted. During this extended phase, a more detailed engineering study should be undertaken to determine the cost of implementation along with more specific estimates of the benefits for PWR plants already in operation or under construction

Outage Probability versus Fairness Trade-off in Opportunistic Relay Selection with Outdated CSI

Directory of Open Access Journals (Sweden)

Vicario JoseLopez

2009-01-01

Full Text Available We analyze the existing trade-offs in terms of system performance versus fairness of a cooperative system based on opportunistic relay selection (ORS and with outdated channel state information (CSI. In particular, system performance is analytically evaluated in terms of outage probability, and the fairness behavior is assessed based on the power consumption at the different relays. In order to improve the fairness behavior of ORS while keeping the selection diversity gain, we propose a relay selection mechanism where the relay with the highest normalized signal-to-noise ratio (SNR is selected for relaying the source's information. The proposed strategy is compared with existing relay selection strategies by adopting a novel graphical representation inspired by expected profit versus risk plots used in modern portfolio theory. As shown in the paper, this strategy allows operating the system in more favorable points of the outage versus fairness region.

Radiological protection for the ANGRA 1 steam generator replacement outage

International Nuclear Information System (INIS)

Oliveira, Magno Jose de; Amaral, Marcos Antonio do; Minelli, Edson; Ferreira, William Alves

2009-01-01

The Angra 1 Nuclear Power Plant (NPP) is a Westinghouse two-loop plant with net output before its 1P16 Outage of 632 MWe, with the Old Steam Generators (OSG) type model D3, which were replaced by two new Steam Generators with feed water-ring system. Localized in Angra dos Reis, Rio de Janeiro - Brazil, Angra 1 started in commercial operation in 1985 and, from the beginning problems related to corrosion have appeared in the Inconel 600 alloy of the tubes. The corrosion problems indicated the necessity for a strong control of the tubes thicknesses and, after a time, the ELETRONUCLEAR decided to replace the OSG. In 2009, ELETRONUCLEAR initiated in January 24, the actions for the Steam Generators Replacement - SGR. During the SGR process, several controls were applied in field, which made possible to have no radiological accidents, no dose limits exceeded, and permitted to achieve a very good result in terms of Collective Dose. This paper describes the radiological controls applied for the Angra 1 Steam Generator Replacement Outage, the radiological protection team sizing and distribution and the obtained results. (author)

Estimating the Propagation of Interdependent Cascading Outages with Multi-Type Branching Processes

Energy Technology Data Exchange (ETDEWEB)

Qi, Junjian; Ju, Wenyun; Sun, Kai

2016-01-01

In this paper, the multi-type branching process is applied to describe the statistics and interdependencies of line outages, the load shed, and isolated buses. The offspring mean matrix of the multi-type branching process is estimated by the Expectation Maximization (EM) algorithm and can quantify the extent of outage propagation. The joint distribution of two types of outages is estimated by the multi-type branching process via the Lagrange-Good inversion. The proposed model is tested with data generated by the AC OPA cascading simulations on the IEEE 118-bus system. The largest eigenvalues of the offspring mean matrix indicate that the system is closer to criticality when considering the interdependence of different types of outages. Compared with empirically estimating the joint distribution of the total outages, good estimate is obtained by using the multitype branching process with a much smaller number of cascades, thus greatly improving the efficiency. It is shown that the multitype branching process can effectively predict the distribution of the load shed and isolated buses and their conditional largest possible total outages even when there are no data of them.

World class performance: the outage/operating cycle continuum

Energy Technology Data Exchange (ETDEWEB)

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

2011-07-01

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

World class performance: the outage/operating cycle continuum

International Nuclear Information System (INIS)

Remphal, M.

2011-01-01

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

Outage Analysis of Mixed Underlay Cognitive RF MIMO and FSO Relaying with Interference Reduction

KAUST Repository

Al-Qahtani, Fawaz S.; El-Malek, Ahmed H. Abd; Ansari, Imran S.; Radaydeh, Redha Mahmoud Mesleh; Zummo, Salam A.

2017-01-01

In this paper, we study the outage performance of multiuser mixed underlay radio frequency (RF)/multidestinations free-space optical (FSO) links. For RF links, we consider a secondary network with multiple users that can communicate with multiple destinations through a relaying node. The relay is equipped with an antenna array at the RF side, and it uses the amplify-and-forward (AF) protocol. The primary users (PUs) are equipped with multiple antennas at transmit and receive nodes. The RF link is subjected to the aggregate PUs interference effect on the secondary network. To reduce the effect of PUs interference on secondary network at the relay node, two interference cancellation (IC) schemes are adopted, which vary in terms of complexity and achieved performance. On the other hand, the multidestination FSO links can be exploited to further enhance the quality of the second hop, and their associated channel models account for pointing errors, intensity modulation/direct detection, and heterodyne detection. For the aforementioned system model, we obtain exact and asymptotic closed-form expressions for the end-to-end outage probability. To further enhance system performance, optimal power allocation between the two hops is obtained based on the derived asymptotic outage probability expressions.

Outage Analysis of Mixed Underlay Cognitive RF MIMO and FSO Relaying with Interference Reduction

KAUST Repository

Al-Qahtani, Fawaz S.

2017-03-22

In this paper, we study the outage performance of multiuser mixed underlay radio frequency (RF)/multidestinations free-space optical (FSO) links. For RF links, we consider a secondary network with multiple users that can communicate with multiple destinations through a relaying node. The relay is equipped with an antenna array at the RF side, and it uses the amplify-and-forward (AF) protocol. The primary users (PUs) are equipped with multiple antennas at transmit and receive nodes. The RF link is subjected to the aggregate PUs interference effect on the secondary network. To reduce the effect of PUs interference on secondary network at the relay node, two interference cancellation (IC) schemes are adopted, which vary in terms of complexity and achieved performance. On the other hand, the multidestination FSO links can be exploited to further enhance the quality of the second hop, and their associated channel models account for pointing errors, intensity modulation/direct detection, and heterodyne detection. For the aforementioned system model, we obtain exact and asymptotic closed-form expressions for the end-to-end outage probability. To further enhance system performance, optimal power allocation between the two hops is obtained based on the derived asymptotic outage probability expressions.

Information needs in nuclear power plants during low power operation modes

Energy Technology Data Exchange (ETDEWEB)

Tommila, Teemu; Fantoni, Paolo F.; Zander, Ralf M.

1998-02-01

During the past few years an increasing attention has been paid to the safety of shutdown and refuelling operations. It has turned out that the risks during shutdown may be comparable to the risks of power operation. The goal of this report is to identify information requirements related to low power operating modes of nuclear power plants. These include, for example, warm and cold shutdowns, refuelling and maintenance, as well as related state transitions such as start-up and shut-down. The focus of the report is on planned refuelling outages and the role of the control room in managing the outage activities. As a starting point, the basic terminology and characteristics of low power operation are discussed. The current situation at nuclear power plants and some recent developments in information technology are reviewed. End-users' requirements and enabling technologies are combined in order to identify the opportunities for new information technology tools in low power operation. The required features of process control systems and maintenance information systems are described. Common plant modelling techniques, open software architectures and functional structuring of the process control system are suggested to be the key issues in the long-term development of operator support systems. On a shorter time scale, new tools solving limited practical problems should be developed and evaluated. This would provide a basis for the features needed for low power operation, including for example, outage planning, on-line risk monitoring, management of outage tasks, adaptive alarm handling, computerised procedures and task-oriented human interfaces. (author)

Excellence through outage planning and scheduling

International Nuclear Information System (INIS)

Ferriole, G.

1987-01-01

The Nuclear and Fossil Generation Division of Electricite de France (EdF) has been the largest nuclear plant operating utility in France since 1984. The size of the units, their standardization, and extensive operating experience were favorable parameters leading to the development of a very complete maintenance organization. Electricite de France believes in the importance of well-defined maintenance concepts. These maintenance concepts contribute to outage performance by requiring a careful consideration of work to be done and by defining the techniques and means of accomplishing this work. In addition to maintenance concepts and careful planning and scheduling, good outage management is achieved through the motivation and dedication of the people involved. It is the key to good operational results

Power Outage - 16 October

CERN Multimedia

2014-01-01

At 19:03 last night, a fire in an 18kV circuit breaker in building 212 led to a blackout on the Meyrin site. The CERN fire brigade rapidly brought the fire under control and power was restored by 22:25. Many CERN systems were affected and have been brought back in to service overnight, this work will continue through the day.

Final report of MoReMO 2011-2012. Modelling resilience for maintenance and outage

International Nuclear Information System (INIS)

Gotcheva, N.; Macchi, L.; Oedewald, P.; Eitrheim, M.H.R.; Axelsson, C.; Reiman, T.; Pietikaeinen, E.

2013-04-01

The project Modelling Resilience for Maintenance and Outage (MoReMO) represents a two-year joint effort by VTT Technical Research Centre of Finland, Institute for Energy Technology (IFE, Norway) and Vattenfall (Sweden) to develop and test new approaches for safety management. The overall goal of the project was to present concepts on how resilience can be operationalized and built in a safety critical and socio-technical context. Furthermore, the project also aimed at providing guidance for other organizations that strive to develop and improve their safety performance in a business driven industry. We have applied four approaches in different case studies: Organisational Core Task modelling (OCT), Functional Resonance Analysis Method (FRAM), Efficiency Thoroughness Trade-Off (ETTO) analysis, and Work Practice and Culture Characterisation. During 2011 and 2012 the MoReMO project team has collected data through field observations, interviews, workshops, and document analysis on the work practices and adjustments in maintenance and outage in Nordic NPPs. The project consisted of two sub-studies, one focused on identifying and assessing adjustments and supporting resilient work practices in maintenance activities, while the other focused on handling performance trade-offs in maintenance and outage, as follows: A. Adjustments in maintenance work in Nordic nuclear power plants (VTT and Vattenfall). B. Handling performance trade-offs - the support of adaptive capacities (IFE and Vattenfall). The historical perspective of maintenance and outage management (Chapter 1.1) was provided by Vattenfall. Together, the two sub-studies have provided valuable insights for understanding the rationale behind work practices and adjustments, their effects on resilience, promoting flexibility and balancing between flexibility and reliability. (Author)

Final report of MoReMO 2011-2012. Modelling resilience for maintenance and outage

Energy Technology Data Exchange (ETDEWEB)

Gotcheva, N.; Macchi, L.; Oedewald, P. [Technical Research Centre of Finland (VTT), Espoo (Finland); Eitrheim, M.H.R. [Institute for Energy Technology (IFE) (Norway); Axelsson, C.; Reiman, T.; Pietikaeinen, E. [Ringhals AB (NPP), Vattenfall AB (Sweden)

2013-04-15

The project Modelling Resilience for Maintenance and Outage (MoReMO) represents a two-year joint effort by VTT Technical Research Centre of Finland, Institute for Energy Technology (IFE, Norway) and Vattenfall (Sweden) to develop and test new approaches for safety management. The overall goal of the project was to present concepts on how resilience can be operationalized and built in a safety critical and socio-technical context. Furthermore, the project also aimed at providing guidance for other organizations that strive to develop and improve their safety performance in a business driven industry. We have applied four approaches in different case studies: Organisational Core Task modelling (OCT), Functional Resonance Analysis Method (FRAM), Efficiency Thoroughness Trade-Off (ETTO) analysis, and Work Practice and Culture Characterisation. During 2011 and 2012 the MoReMO project team has collected data through field observations, interviews, workshops, and document analysis on the work practices and adjustments in maintenance and outage in Nordic NPPs. The project consisted of two sub-studies, one focused on identifying and assessing adjustments and supporting resilient work practices in maintenance activities, while the other focused on handling performance trade-offs in maintenance and outage, as follows: A. Adjustments in maintenance work in Nordic nuclear power plants (VTT and Vattenfall). B. Handling performance trade-offs - the support of adaptive capacities (IFE and Vattenfall). The historical perspective of maintenance and outage management (Chapter 1.1) was provided by Vattenfall. Together, the two sub-studies have provided valuable insights for understanding the rationale behind work practices and adjustments, their effects on resilience, promoting flexibility and balancing between flexibility and reliability. (Author)

Use of workstations in the ANAV outage tasks course access

International Nuclear Information System (INIS)

Gómez Rodriguez, Carlos A.

2016-01-01

The access course for the Asco and Vandellos II Nuclear Power Plants contains all of the training that is considered necessary in compliance with the stipulations of current legislation for the pupils to carry out their activity at the plants. Given the heterogeneity of the special characteristics of those workers who take part in the outage tasks at our plants we have sought to improve the learning values of their access course with the inclusion of Work Stations since 2013. Several changes have been made in the training action since that date to make it more interactive.

Development of an Overview Display to Allow Advanced Outage Control Center Management to Quickly Evaluate Outage Status

Energy Technology Data Exchange (ETDEWEB)

St Germain, Shawn Walter [Idaho National Lab. (INL), Idaho Falls, ID (United States); Hugo, Jacques Victor [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2016-09-01

This report describes recent advances made in developing a framework for the design of visual outage information presentation, as well as an overview of the scientific principles that informed the development of the visualizations.

Power System Extreme Event Detection: The VulnerabilityFrontier

Energy Technology Data Exchange (ETDEWEB)

Lesieutre, Bernard C.; Pinar, Ali; Roy, Sandip

2007-10-17

In this work we apply graph theoretic tools to provide aclose bound on a frontier relating the number of line outages in a gridto the power disrupted by the outages. This frontier describes theboundary of a space relating the possible severity of a disturbance interms of power disruption, from zero to some maximum on the boundary, tothe number line outages involved in the event. We present the usefulnessof this analysis with a complete analysis of a 30 bus system, and presentresults for larger systems.

Cooperative AF Relaying in Spectrum-Sharing Systems: Outage Probability Analysis under Co-Channel Interferences and Relay Selection

KAUST Repository

Xia, Minghua

2012-11-01

For cooperative amplify-and-forward (AF) relaying in spectrum-sharing wireless systems, secondary users share spectrum resources originally licensed to primary users to communicate with each other and, thus, the transmit power of secondary transmitters is strictly limited by the tolerable interference powers at primary receivers. Furthermore, the received signals at a relay and at a secondary receiver are inevitably interfered by the signals from primary transmitters. These co-channel interferences (CCIs) from concurrent primary transmission can significantly degrade the performance of secondary transmission. This paper studies the effect of CCIs on outage probability of the secondary link in a spectrum-sharing environment. In particular, in order to compensate the performance loss due to CCIs, the transmit powers of a secondary transmitter and its relaying node are respectively optimized with respect to both the tolerable interference powers at the primary receivers and the CCIs from the primary transmitters. Moreover, when multiple relays are available, the technique of opportunistic relay selection is exploited to further improve system performance with low implementation complexity. By analyzing lower and upper bounds on the outage probability of the secondary system, this study reveals that it is the tolerable interference powers at primary receivers that dominate the system performance, rather than the CCIs from primary transmitters. System designers will benefit from this result in planning and designing next-generation broadband spectrum-sharing systems.

Outage performance of reactive cooperation in Nakagami-m fading channels

KAUST Repository

Benjillali, Mustapha

2010-06-01

In this paper, we investigate the outage performance of Decode-and-Forward with reactive relaying in dual-hop cooperetive Nakagaml-m fading links. The destination, based on the umque knowledge of local second hop channel state information, selects the best relay to increase the chances of cooperation when the direct link is also available. After deriving the exact distribution of the variables of interest, the outage probability of the system - with and without the direct link - is obtained in closed-form, and the ε-outage capacity is derived in the particular c.se wh.ere the channel model is reduced to a Rayleigh fading. Simulation results confirm the accuracy of our analysis for a large selection of system and fading parameters.

Wolsong Unit 1 restart chemistry procedures during retubing outage

International Nuclear Information System (INIS)

Yun, Hyunran; Lee, Sarang; Moon, Yunyong; Kim, Seoyul

2015-01-01

Lay-up is aimed at protecting systems from degradation during outage, mainly by minimizing corrosion and particularly, when the outage is longer than 16 weeks. Due to the intrinsic design of CANDU reactors, their horizontal fuel channels should be replaced for another service life time. This poster presents the lay-up guidelines and methods recommended for re-tubing outage based on the first re-tubing operation made in Korea (at the Wolsung Unit 1). It is shown that dry lay-up with specific gas blanket was the sole choice for the primary heat transfer system, the moderator system and the steam cycle system while wet lay-up under circulation was recommended for the end shield cooling system and the liquid zone control system. The water filled part of steam generators, of the liquid zone control system and of the end shield cooling system was maintained normal

Outage performance improvement by state of the art reactor stud tensioning

International Nuclear Information System (INIS)

Oehler, Horst Werner; Vervliet, Herman

2006-01-01

Actual methods of reactor closing, i.e. cover to vessel sealing, is based on the creation of an equal load to the sealing circumference by tensioning all reactor studs with an equal force. This method ensures leak tightness through equal compression of the reactor seal in normal circumstances and is largely applied for all types of reactors throughout many generations and designs of nuclear power stations. The tension generated in each reactor stud is controlled indirectly by measuring the reactor stud elongation while under stress. Most studs are designed to measure this elongation easily by conventional or more advanced systems (from individual clock gauge to integrated digital transmission to a computer screen). It is this elongation value, prescribed by the reactor vessel/cover manufacturer which must be respected and demonstrated during all reactor closing operations, weather they take place for initial hydro testing, refuelling operations or periodical hydraulic tests of the primary circuit. Closing (and re-opening) of reactor vessels has become a routine operation as it is required for fuel reloading of the reactor core. This operation is performed on all PWR and BWR type of reactors with a large variety of tooling. As most of the utilities have implemented maintenance optimisation programs, the refuelling outage is reduced to a sequence of activities that allow quick and efficient refuelling of the core. The performance and efficiency of instrumentation and tooling deployed during these essential activities are of the utmost importance to minimise the critical path of the refuelling outage. Today, in support of outage performance, many utilities have invested in new and refurbished tooling to allow quick and efficient opening and closing of the reactor vessel. The features and properties of the most performing multi stud tensioning machines currently in service in nuclear power stations world wide (Africa, Europe, Asia and USA) are presented in the paper

Power feedback effects in the LEM code

International Nuclear Information System (INIS)

Kromar, M.

1999-01-01

The nodal diffusion code LEM has been extended with the power feedback option. Thermohydraulic and neutronic coupling is covered with the Reactivity Coefficient Method. Presented are results of the code testing. Verification is done on the typical non-uprated NPP Krsko reload cycles. Results show that the code fulfill objectives arising in the process of reactor core analysis.(author)

Outage Analysis of Spectrum-Sharing over M-Block Fading with Sensing Information

KAUST Repository

Alabbasi, Abdulrahman; Rezki, Zouheir; Shihada, Basem

2016-01-01

on the outage probability with tractable expressions. These bounds allow us to derive the exact diversity order of the secondary user’s outage probability. To further enhance the system’s performance, we also investigate the impact of including the sensing

Outage Performance Analysis of Relay Selection Schemes in Wireless Energy Harvesting Cooperative Networks over Non-Identical Rayleigh Fading Channels.

Science.gov (United States)

Do, Nhu Tri; Bao, Vo Nguyen Quoc; An, Beongku

2016-02-26

In this paper, we study relay selection in decode-and-forward wireless energy harvesting cooperative networks. In contrast to conventional cooperative networks, the relays harvest energy from the source's radio-frequency radiation and then use that energy to forward the source information. Considering power splitting receiver architecture used at relays to harvest energy, we are concerned with the performance of two popular relay selection schemes, namely, partial relay selection (PRS) scheme and optimal relay selection (ORS) scheme. In particular, we analyze the system performance in terms of outage probability (OP) over independent and non-identical (i.n.i.d.) Rayleigh fading channels. We derive the closed-form approximations for the system outage probabilities of both schemes and validate the analysis by the Monte-Carlo simulation. The numerical results provide comprehensive performance comparison between the PRS and ORS schemes and reveal the effect of wireless energy harvesting on the outage performances of both schemes. Additionally, we also show the advantages and drawbacks of the wireless energy harvesting cooperative networks and compare to the conventional cooperative networks.

Outage Performance of Flexible OFDM Schemes in Packet-Switched Transmissions

Directory of Open Access Journals (Sweden)

Romain Couillet

2009-01-01

Full Text Available α-OFDM, a generalization of the OFDM modulation, is proposed. This new modulation enhances the outage capacity performance of bursty communications. The α-OFDM scheme is easily implementable as it only requires an additional time symbol rotation after the IDFT stage and a subsequent phase rotation of the cyclic prefix. The physical effect of the induced rotation is to slide the DFT window over the frequency spectrum. When successively used with different angles α at the symbol rate, α-OFDM provides frequency diversity in block fading channels. Interestingly, simulation results show a substantial gain in terms of outage capacity and outage BER in comparison with classical OFDM modulation schemes. The framework is extended to multiantenna and multicellular OFDM-based standards. Practical simulations, in the context of 3GPP-LTE, called hereafter α-LTE, sustain our theoretical claims.

Outage capacity of multicarrier systems

KAUST Repository

Yilmaz, Ferkan; Alouini, Mohamed-Slim

2010-01-01

The probability density function and the cumulative distribution function of the product of shifted Gamma variates are obtained in terms of the generalized Fox's H function. Using these new results, the exact outage capacity of multi carrier transmission through a slow Nakagami-m fading channel is presented. Moreover, it is shown that analytical and simulation results are in perfect agreement. © 2009 IEEE.

Allowable outage analysis for the LOFT CIS and reflood assist bypass valves

International Nuclear Information System (INIS)

Trainer, J.E.; Matthews, S.D.

1977-06-01

To determine the outage time allowable for a typical 1 of 2 redundant valve configuration, a Markov model was created to analyze the various operating states for the valves. Since no performance criteria have been specified, an availability model was constructed with regard to the valve outage

Outage performance analysis of underlay cognitive RF and FSO wireless channels

KAUST Repository

Ansari, Imran Shafique

2014-09-01

In this work, the outage performance analysis of a dual-hop transmission system composed of asymmetric radio frequency (RF) channel cascaded with a free-space optical (FSO) link is presented. For the RF link, an underlay cognitive network is considered where the secondary users share the spectrum with licensed primary users. Indoor femtocells act as a practical example for such networks. More specifically, it is assumed that the RF link applies power control to maintain the interference at the primary network below a predetermined threshold. While the RF channel is modeled by the Rayleigh fading distribution, the FSO link is modeled by a unified Gamma-Gamma turbulence distribution. The FSO link accounts for pointing errors and both types of detection techniques (i.e. heterodyne detection as well as intensity modulation/direct detection (IM/DD)). With this model, a new exact closed-form expression is derived for the outage probability of the end-To-end signal-To-noise ratio of these systems in terms of the Meijer\\'s G function and the Fox\\'s H functions under fixed amplify-and-forward relay scheme. All new analytical results are verified via computer-based Monte-Carlo simulations and are illustrated by some selected numerical results.

Outage capacity of multicarrier systems

KAUST Repository

Yilmaz, Ferkan

2010-01-01

The probability density function and the cumulative distribution function of the product of shifted Gamma variates are obtained in terms of the generalized Fox\\'s H function. Using these new results, the exact outage capacity of multi carrier transmission through a slow Nakagami-m fading channel is presented. Moreover, it is shown that analytical and simulation results are in perfect agreement. © 2009 IEEE.

Outage Performance Analysis of Relay Selection Schemes in Wireless Energy Harvesting Cooperative Networks over Non-Identical Rayleigh Fading Channels †

Science.gov (United States)

Do, Nhu Tri; Bao, Vo Nguyen Quoc; An, Beongku

2016-01-01

In this paper, we study relay selection in decode-and-forward wireless energy harvesting cooperative networks. In contrast to conventional cooperative networks, the relays harvest energy from the source’s radio-frequency radiation and then use that energy to forward the source information. Considering power splitting receiver architecture used at relays to harvest energy, we are concerned with the performance of two popular relay selection schemes, namely, partial relay selection (PRS) scheme and optimal relay selection (ORS) scheme. In particular, we analyze the system performance in terms of outage probability (OP) over independent and non-identical (i.n.i.d.) Rayleigh fading channels. We derive the closed-form approximations for the system outage probabilities of both schemes and validate the analysis by the Monte-Carlo simulation. The numerical results provide comprehensive performance comparison between the PRS and ORS schemes and reveal the effect of wireless energy harvesting on the outage performances of both schemes. Additionally, we also show the advantages and drawbacks of the wireless energy harvesting cooperative networks and compare to the conventional cooperative networks. PMID:26927119

Outage Analysis of Asymmetric RF-FSO Systems

KAUST Repository

Ansari, Imran Shafique; Abdallah, Mohamed M.; Alouini, Mohamed-Slim; Qaraqe, Khalid A.

2017-01-01

In this work, the outage performance analysis of a dual-hop transmission system composed of asymmetric radio frequency (RF) channels cascaded with free-space optical (FSO) links is presented. The RF links are modeled by the Rayleigh fading

Nuclear power investment risk economic model

International Nuclear Information System (INIS)

Postula, F.D.; Houghton, W.J.

1986-01-01

This paper describes the economic model which was developed to evaluate the net costs incurred by an owner due to an accident induced outage at a nuclear power plant. During such an outage, the portion of the plant operating costs associated with power production are saved; however the owner faces a sizable expense as fossil fuels are burned as a substitute for power from the incapacitated nuclear plant. Additional expenses are incurred by the owner for plant repair and, if necessary, decontamination cost. The model makes provision for mitigating these costs by sales of power, property damage insurance payments, tax write-offs and increased rates

Outage analysis of opportunistic decode-and-forward relaying

KAUST Repository

Tourki, Kamel

2010-09-01

In this paper, we investigate a dual-hop opportunistic decode-and-forward relaying scheme where the source may or not be able to communicate directly with the destination. We first derive statistics based on exact probability density function (PDF) of each hop. Then, the PDFs are used to determine closed-form outage probability expression for a transmission rate R. Furthermore, we evaluate the asymptotic outage performance and the diversity order is deduced. Unlike existing works where the analysis focused on high signal-to-noise ratio (SNR) regime, such results are important to enable the designers to take decisions regarding practical systems that operate at low SNR regime. We show that performance simulation results coincide with our analytical results under practical assumption of unbalanced hops. © 2010 IEEE.

Cooperative jamming power control to enhance secrecy communications of AF Relaying systems for Rayleigh fading channel

KAUST Repository

Park, Kihong; Alouini, Mohamed-Slim

2012-01-01

allocation; (i) rate-optimal power allocation and (ii) outage-optimal power allocation. More specifically, without the instantaneous channel knowledge for the eavesdropper side, the outage probability of the secrecy rate is minimized with respect

Bingham Pump Outage Pits: Environmental information document

International Nuclear Information System (INIS)

Pekkala, R.O.; Jewell, C.E.; Holmes, W.G.; Marine, I.W.

1987-03-01

Seven waste sites known as the Bingham Pump Outage Pits located in areas of the Savannah River Plant (SRP) received solid waste containing an estimated 4 Ci of low-level radioactivity in 1957-1958. These sites were subsequently backfilled and have been inactive since that time. Most of the radioactivity at the Bingham Pump Outage Pits has been eliminated by radioactive decay. A total of approximately 1 Ci of activity (primarily 137 Cs and 90 Sr) is estimated to remain at the seven sites. The closure options considered for the Bingham Pump Outage Pits are waste removal and closure, no waste removal and closure, and no action. The predominant pathways for human exposure to chemical and/or radioactive constituents are through surface, subsurface, and atmospheric transport. Modeling calculations were made to determine the risks to human population via these general pathways for the three postulated closure options. An ecological assessment was conducted to predict the environmental impacts on aquatic and terrestrial biota. The relative costs for each of the closure options were estimated. Evaluation indicates that the relative human health risks for all closure options are small. The greatest public risk would occur after the waste site was released to unrestricted public use (assumed to occur in Year 2085) via the groundwater pathway to a well. The cost estimates show that the waste removal and closure option is the most expensive (89.6 million dollars). The cost of the no waste removal and the no action options is $800,000. 35 refs., 26 figs., 47 tabs

Evaluation of potential severe accidents during low power and shutdown operations at Grand Gulf, Unit 1. Volume 2, Part 1C: Analysis of core damage frequency from internal events for plant operational State 5 during a refueling outage, Main report (Sections 11--14)

International Nuclear Information System (INIS)

Whitehead, D.; Darby, J.; Yakle, J.

1994-06-01

This document contains the accident sequence analysis of internally initiated events for Grand Gulf, Unit 1 as it operates in the Low Power and Shutdown Plant Operational State 5 during a refueling outage. The report documents the methodology used during the analysis, describes the results from the application of the methodology, and compares the results with the results from two full power analyses performed on Grand Gulf

Evaluation of potential severe accidents during low power and shutdown operations at Grand Gulf, Unit 1: Analysis of core damage frequency from internal events for Plant Operational State 5 during a refueling outage. Volume 2, Part 2: Internal Events Appendices A to H

International Nuclear Information System (INIS)

Darby, J.; Whitehead, D.; Staple, B.; Dandini, V.

1994-06-01

This document contains the accident sequence analysis of internally initiated events for Grand Gulf, Unit 1 as it operates in the Low Power and Shutdown Plant Operational State 5 during a refueling outage. The report documents the methodology used during the analysis, describes the results from the application of the methodology, and compares the results with the results from two full power analyses performed on Grand Gulf

Cooperative jamming power control to enhance secrecy communications of AF Relaying systems for Rayleigh fading channel

KAUST Repository

Park, Kihong

2012-09-01

In this paper, we investigate secrecy communications in two-hop wireless relaying networks which consist of one source, one amplify-and-forward (AF) relay, one legitimate destination, and one eavesdropper. To prevent the eavesdropper from intercepting the source message, we make the destination send the intended noise to the AF relay during the first phase. This is referred to as cooperative jamming. According to the channel information at the destination, we address two types of jamming power allocation; (i) rate-optimal power allocation and (ii) outage-optimal power allocation. More specifically, without the instantaneous channel knowledge for the eavesdropper side, the outage probability of the secrecy rate is minimized with respect to the intended noise power level. We show that the outage-optimal allocation gives almost the same outage probability as the rateoptimal one. In addition, the jamming power consumption can be significantly reduced compared to the fixed and rate-optimal power allocation methods. © 2012 IEEE.

Chattanooga Electric Power Board Case Study Distribution Automation

Energy Technology Data Exchange (ETDEWEB)

Glass, Jim [Chattanooga Electric Power Board (EPB), TN (United States); Melin, Alexander M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Starke, Michael R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ollis, Ben [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2016-10-01

In 2009, the U.S. Department of Energy under the American Recovery and Reinvestment Act (ARRA) awarded a grant to the Chattanooga, Tennessee, Electric Power Board (EPB) as part of the Smart Grid Investment Grant Program. The grant had the objective “to accelerate the transformation of the nation’s electric grid by deploying smart grid technologies.” This funding award enabled EPB to expedite the original smart grid implementation schedule from an estimated 10-12 years to 2.5 years. With this funding, EPB invested heavily in distribution automation technologies including installing over 1,200 automated circuit switches and sensors on 171 circuits. For utilities considering a commitment to distribution automation, there are underlying questions such as the following: “What is the value?” and “What are the costs?” This case study attempts to answer these questions. The primary benefit of distribution automation is increased reliability or reduced power outage duration and frequency. Power outages directly impact customer economics by interfering with business functions. In the past, this economic driver has been difficult to effectively evaluate. However, as this case study demonstrates, tools and analysis techniques are now available. In this case study, the impact on customer costs associated with power outages before and after the implementation of distribution automation are compared. Two example evaluations are performed to demonstrate the benefits: 1) a savings baseline for customers under normal operations1 and 2) customer savings for a single severe weather event. Cost calculations for customer power outages are performed using the US Department of Energy (DOE) Interruption Cost Estimate (ICE) calculator2. This tool uses standard metrics associated with outages and the customers to calculate cost impact. The analysis shows that EPB customers have seen significant reliability improvements from the implementation of distribution automation. Under

Modernization of electric power systems of the Laguna Verde Nuclear Power Plant

International Nuclear Information System (INIS)

Gabaldon, M. A.; Gonzalez, J. J.; Prieto, I.

2011-01-01

The Power Increase Project of Laguna Verde Nuclear Plant has entailed the replacement, in one unique outage, of the main power electrical systems of the Plant (Isolated Phase Bars, Generator Circuit Breaker and Main Transformer) as well as the replacement of the Turbo-group. The simultaneous substitution of these entire system has never been done by any other Plant in the world, representing an engineering challenge that embraced the design of the new equipment up to the planning, coordination and management of the construction and commissioning works, which were successfully carried out by Iberdrola within the established outage period /47 days) for both units. (Author)

Simulations of the design basis accident at conditions of power increase and the o transient of MSIV at overpressure conditions of the Laguna Verde Power Station

International Nuclear Information System (INIS)

Araiza M, E.; Nunez C, A.

2001-01-01

This document presents the analysis of the simulation of the loss of coolant accident at uprate power conditions, that is 2027 MWt (105% of the current rated power of 1931MWt). This power was reached allowing an increase in the turbine steam flow rate without changing the steam dome pressure value at its rated conditions (1020 psiaJ. There are also presented the results of the simulation of the main steam isolation va/ve transient at overpressure conditions 1065 psia and 1067 MWt), for Laguna Verde Nuclear Power Station. Both simulations were performed with the best estimate computer code TRA C BF1. The results obtained in the loss of coolant accident show that the emergency core coolant systems can recover the water level in the core before fuel temperature increases excessively, and that the peak pressure reached in the drywell is always below its design pressure. Therefore it is concluded that the integrity of the containment is not challenged during a loss of coolant accident at uprate power conditions.The analysis of the main steam isolation valve transients at overpressure conditions, and the analysis of the particular cases of the failure of one to six safety relief valves to open, show that the vessel peak pressures are below the design pressure and have no significant effect on vessel integrity. (Author)

Feasibility Study of Power Uprate Using Ultrasonic Flow Meters in NPPs

International Nuclear Information System (INIS)

Kim, Tae Mi; Heo, Gyun Young

2010-01-01

Feedwater flowrate is an important input parameter in establishing the plant's operating power level. In Korean nuclear power plants, venturi flow meters have been used for measuring the feedwater flow of the secondary side. However, as time goes on, the fouling in venture meters could cause measurement uncertainties to grow and that could lead to operation at less than about 2% of the licensed thermal power limit. In order to resolve the problem, nuclear power plants in other countries use Ultrasonic Flow Meters (UFMs) which have relatively lower measurement uncertainty (about 0.5%) instead of venturi flow meters and have reduced the errors from the fouling in venturi-type flow meters. USA amended 10 CFR 50 Appendix K so that US nuclear power plants can use real value of Core Operating Limit Supervisory System (COLSS) uncertainty, which is currently fixed as 2%, by adopting the UFM. Korea also has been amended the law in order to get benefits from the technology. In this study, we are going to present the fundamental principles of UFMs and the advantages and disadvantages of its installation. Also, we inquire into the conventional uses of UFMs in the overseas sites and then check what is needed to consider for its domestic application

Delay-Limited Capacity in the Low Power Regime

KAUST Repository

Rezki, Zouheir

2016-02-11

Outage performance of the M-block fading with additive white Gaussian noise (BF-AWGN) is investigated in the low-power regime. We consider delay-constrained constant-rate communications with perfect channel state information (CSI) at both the transmitter and the receiver (CSI-TR), under a shortterm power constraint (STPC) and a long-term power constraint (LTPC). Subject to STPC, we show that selection diversity that allocates all the power to the strongest block is asymptotically optimal. Then, we provide a simple characterization of the outage probability in the regime of interest. We quantify the reward due to CSI-TR over the constant-rate constant-power scheme and show that this reward increases with the delay constraint. For instance, for Rayleigh fading, we find that a power gain up to 4.3 dB is achievable. Subject to LTPC, we show that the above guidelines still holds and that the outage performance improves due to the flexibility of the LTPC over the STPC. More interestingly, we prove that LTPC allows zero-outage communication even at low SNR and characterize the delaylimited capacity at low SNR in a simple form. More precisely, we establish that the delay-limited capacity scales linearly with the power constraint, for a given M < 1. Our framework highlights the benefit of fading at low SNR as the delay-limited capacity may outperform the AWGN capacity. For instance, for Rayleigh fading and with M = 3, the delay-limited capacity is 16% higher than the capacity of an AWGN channel.

Performance Shaping Factors Assessments and Application to PHWR Outages

Energy Technology Data Exchange (ETDEWEB)

Lee, Seung Woo

2007-02-15

Human reliability analysis is definitely related to the quality of PSA because human errors have been identified as major contributors to PSA. According to NRC's 'Office of analysis and evaluation of operational data (AEOD)',82% of the reactor trips and accident during outage is caused by the events related to human errors. There is, however, no one HRA method universally accepted. Furthermore, HRA during PHWR outages has not been performed around the world yet. HRA during PHWR outages is especially important since manual management of operator is more required during PHWR. In this study, accident scenarios which HYU developed are used to perform a quantification of human error probability. In this study, overall procedures of standard HRA methodology are introduced and follows the quantification of 10 possible selected human actions during PHWR outages based on standard HRA methodology. To see the verification, quantified values were compared with the values from 'Generic CANDU Probabilistic Safety Assessment' and the values estimated by ASEP.Core Damage Frequency was estimated 3.35 x 10{sup -4} more higher than CDF estimated by AECL data. It was considered that the differences between the HEPs for OPAFW and OPECC3 make CDF higher. Therefore, complementary study of reestimating HEP for OPAFW and OPECC3 in detail is required for increasing the qualities of HRA and PSA. Moreover, one of the difficulties in performing human reliability analysis is to evaluate performance shaping factors which represent the characteristics and circumstances. For assessing a specific human action more exactly, it is necessary to consider all of the PSFs at the same time which makes an effect on the human action. Also, it requires the effect comparison among PSFs to minimize the uncertainties which are usually caused by the subjective judgements of HRA analysts. To see the sensitivity, performance shaping factors of each decision rule are changed which resulted

Performance Shaping Factors Assessments and Application to PHWR Outages

International Nuclear Information System (INIS)

Lee, Seung Woo

2007-02-01

Human reliability analysis is definitely related to the quality of PSA because human errors have been identified as major contributors to PSA. According to NRC's 'Office of analysis and evaluation of operational data (AEOD)',82% of the reactor trips and accident during outage is caused by the events related to human errors. There is, however, no one HRA method universally accepted. Furthermore, HRA during PHWR outages has not been performed around the world yet. HRA during PHWR outages is especially important since manual management of operator is more required during PHWR. In this study, accident scenarios which HYU developed are used to perform a quantification of human error probability. In this study, overall procedures of standard HRA methodology are introduced and follows the quantification of 10 possible selected human actions during PHWR outages based on standard HRA methodology. To see the verification, quantified values were compared with the values from 'Generic CANDU Probabilistic Safety Assessment' and the values estimated by ASEP.Core Damage Frequency was estimated 3.35 x 10 -4 more higher than CDF estimated by AECL data. It was considered that the differences between the HEPs for OPAFW and OPECC3 make CDF higher. Therefore, complementary study of reestimating HEP for OPAFW and OPECC3 in detail is required for increasing the qualities of HRA and PSA. Moreover, one of the difficulties in performing human reliability analysis is to evaluate performance shaping factors which represent the characteristics and circumstances. For assessing a specific human action more exactly, it is necessary to consider all of the PSFs at the same time which makes an effect on the human action. Also, it requires the effect comparison among PSFs to minimize the uncertainties which are usually caused by the subjective judgements of HRA analysts. To see the sensitivity, performance shaping factors of each decision rule are changed which resulted in changes of core damage

Optimization of costs for the DOEL 3 steam generator replacement

International Nuclear Information System (INIS)

Leblois, C.

1994-01-01

Several aspects of steam generator replacement economics are discussed on the basis of the recent replacement carried out in the Doel 3 unit. The choice between repair of replacement policies, as well as the selection of the intervention date were based on a comparison of costs in which various possible scenarios were examined. The contractual approach for the different works to be performed was also an important point, as well as the project organization in which CAD played an important role. This organization allowed to optimize the outage duration and to realize numerous interventions in the reactor building in parallel with the replacement itself. A last aspect of the optimization of costs is the possibility to uprate the plant power. In the case of Doel 3, the plant restarted with a nominal power increased by 10%, of which 5,7% were possible by the increase of the SG heat transfer area. (Author) 6 refs

Programming and organisation of unit outages

International Nuclear Information System (INIS)

Hadjidakis, Y.; Cezard, C.; Audierne, J.

1997-01-01

The unit outages are scheduled every 12 to 18 months for fuel reloading. The success of these shutdowns, with the whole of objectives (duration, dosimetry, costs), with maintaining the safety level, is an important stake for the competitiveness of the enterprise. In this article are described the planning, the experience return and the organisation of scheduled shutdowns which have contribute to the improvement of availability. (N.C.)

Exact Outage Probability of Dual-Hop CSI-Assisted AF Relaying Over Nakagami-m Fading Channels

KAUST Repository

Xia, Minghua; Aissa, Sonia; Wu, Yik-Chung

2012-01-01

to evaluate the outage performance of the system under study. The analytical results of outage probability coincide exactly with Monte-Carlo simulation results and outperform the previously reported upper bounds in the low and medium SNR regions.

BINARY PARTICLE SWARM OPTIMIZATION APPROACH FOR RANDOM GENERATION OUTAGE MAINTENANCE SCHEDULING

Directory of Open Access Journals (Sweden)

K. Suresh

2013-01-01

Full Text Available This paper presents a methodology for maintenance scheduling (MS of generators using binary particle swarm optimization (BPSO based probabilistic approach. The objective of this paper is to reduce the loss of load probability (LOLP for a power system. The capacity outage probability table (COPT is the initial step in creating maintenance schedule using the probabilistic levelized risk method. This paper proposes BPSO method which is used to construct the COPT. In order to mitigate the effects of probabilistic levelized risk method, BPSO based probabilistic levelized risk method is embarked on a MS problem. In order to validate the effectiveness of the proposed algorithm, case study results for simple five unit system can accomplish a significant levelization in the reliability indices that make possible to evaluate system generation system adequacy in the MS horizon of the power system. The proposed method shows better performance compared with other optimization methods and conventional method with improved search performance.

Kozloduy NPP units 5 and 6 modernization program. Measures implementation in outages

International Nuclear Information System (INIS)

Naydenov, N.; Mignone, O.

2004-01-01

The units 5 and 6 modernization program is a highly demanding program composed by many plant modifications and studies about plant conditions. The program measures implementation during the units outages represents a challenge by the need to compromise shut down duration with the workload related to measures installation. The units shutdown duration should be kept to the planned duration. In parallel, contractors work has to be organized, planned and performed to allow successful measures completion. In accordance with the contract requirements, contractors prepare installation documents which comprise all activities to be performed during the installation and testing of the measures. The subcontractors complement these installation documents with the project organization and execution documents, which include the manpower skills, qualifications, work orders, and other important installation instructions and information. Contractors prepared detailed installation schedules, and these were integrated by Parsons E and C in the Integrated installation schedule. The integrated schedule proved to be useful to identify possible area usage conflicts and manpower overlapping, with appropriate results for electrical, instrumentation and control work, and for the utilization of the polar crane in the containment building. Contractors installation schedules were updated on a weekly basis, showing variances versus the target, and manpower histograms for the resource loading. Organization of contractors work was supported by KNPP plant outage meetings, in which status and problems were addressed, and solution and/or corrective actions defined for further implementation. KNPP meetings were planned on a daily basis for most relevant or critical measures, or on a weekly basis for less intensive measures. KNPP meetings proved to be an excellent communication tool for keeping the measures under control and monitoring KNPP defined personnel responsible for authorizing changes, in

Pricing power outages in the Netherlands

NARCIS (Netherlands)

Baarsma, B.E.; Hop, J.P.

2009-01-01

In most Western countries, the power grid provides electricity more than 99% of the time. To maintain reliability at such high levels, energy companies have to continually invest in electric transmission- and distribution systems. Since customers of electricity cannot switch from one distribution

The course of a true outage never ran so smooth

International Nuclear Information System (INIS)

Harberts, Craig

1994-01-01

In order to improve the performance of outages at San Onofre Nuclear Generating Station in California, the working structure of the entire organisation has had to be radically altered, in order to bring San Onofre up to standard with other nuclear plants known to be performing well. Working systems were simplified and efficiency improved. Personnel needed to be remotivated to work cooperatively and the outage budget process was revised to include input from all relevant organizations, historical costs and benchmark information from other plants that performed well. Finally, the decision making and teamwork culture has altered radically at San Onofre over the last decade. (UK)

Guide for prioritizing power plant productivity improvement projects: handbook of availability improvement methodology

International Nuclear Information System (INIS)

1981-01-01

As part of its program to help improve electrical power plant productivity, the Department of Energy (DOE) has developed a methodology for evaluating productivity improvement projects. This handbook presents a simplified version of this methodology called the Availability Improvement Methodology (AIM), which provides a systematic approach for prioritizing plant improvement projects. Also included in this handbook is a description of data taking requirements necessary to support the AIM methodology, benefit/cost analysis, and root cause analysis for tracing persistent power plant problems. In applying the AIM methodology, utility engineers should be mindful that replacement power costs are frequently greater for forced outages than for planned outages. Equivalent availability includes both. A cost-effective ranking of alternative plant improvement projects must discern between those projects which will reduce forced outages and those which might reduce planned outages. As is the case with any analytical procedure, engineering judgement must be exercised with respect to results of purely mathematical calculations

Outage Analysis of Asymmetric RF-FSO Systems

KAUST Repository

Ansari, Imran Shafique

2017-03-20

In this work, the outage performance analysis of a dual-hop transmission system composed of asymmetric radio frequency (RF) channels cascaded with free-space optical (FSO) links is presented. The RF links are modeled by the Rayleigh fading distribution and the FSO links are modeled by Malaga (M) turbulence distribution. The FSO links account for pointing errors and both types of detection techniques (i.e. heterodyne detection as well as intensity modulation/direct detection (IM/DD)). Transmit diversity is applied at the source, selection combining is applied at the destination, and the relay is equipped with single RF receive antenna and single aperture for relaying the information over FSO links. With this model, a new exact closed-form expression is derived for the outage probability of the end-to- end signal-to-noise ratio of such communication systems in terms of the Meijer\\'s G function under fixed amplify-and-forward relay scheme. All new analytical results are verified via computer-based Monte-Carlo simulations and are illustrated by some selected numerical results.

On stochastic geometry modeling of cellular uplink transmission with truncated channel inversion power control

KAUST Repository

Elsawy, Hesham

2014-08-01

Using stochastic geometry, we develop a tractable uplink modeling paradigm for outage probability and spectral efficiency in both single and multi-tier cellular wireless networks. The analysis accounts for per user equipment (UE) power control as well as the maximum power limitations for UEs. More specifically, for interference mitigation and robust uplink communication, each UE is required to control its transmit power such that the average received signal power at its serving base station (BS) is equal to a certain threshold ρo. Due to the limited transmit power, the UEs employ a truncated channel inversion power control policy with a cutoff threshold of ρo. We show that there exists a transfer point in the uplink system performance that depends on the following tuple: BS intensity λ, maximum transmit power of UEs Pu, and ρo. That is, when Pu is a tight operational constraint with respect to (w.r.t.) λ and ρo, the uplink outage probability and spectral efficiency highly depend on the values of λ and ρo. In this case, there exists an optimal cutoff threshold ρ*o, which depends on the system parameters, that minimizes the outage probability. On the other hand, when Pu is not a binding operational constraint w.r.t. λ and ρo, the uplink outage probability and spectral efficiency become independent of λ and ρo. We obtain approximate yet accurate simple expressions for outage probability and spectral efficiency, which reduce to closed forms in some special cases. © 2002-2012 IEEE.

Bruce A - performance power

Energy Technology Data Exchange (ETDEWEB)

Boucher, P. [Bruce Power, Tiverton, ON (Canada)

2015-07-01

This paper discusses the strategy for improving performance at Bruce Power. The key to excellence is changing behaviours. Reinforcing and enforcing expectations, aligned with the 2015 operating to the Highest Standards Site Initiative. Long term equipment strategies, supported by the 2015 Equipment Health Site Initiative, individual and group accountability for online/outage Work Management, with further gains through 2015 Maintenance Alignment and Resource Strategy (MARS) Site Initiative. Results showed human performance improvement, more reliable and predictable units and outage performance improvement.

Short term braking capability during power interruptions for integrated matrix converter

DEFF Research Database (Denmark)

Klumpner, Christian; Blaabjerg, Frede

2004-01-01

attractive. Sinusoidal input currents and bi-directional power flow are other advantages of the matrix converter, but it is less immune to power grid disturbances compared to a standard ASD. In hoisting applications, short-term braking capability during a power outage is needed until the mechanical brake...... engages or to perform more effective a combined braking. This paper proposes a new method to provide short-term braking capability during a power outage for matrix converters. A braking chopper is needed in the clamp circuit, which allows for a drastically reduction of the capacitor size. The power flow...

Proceedings of a joint OECD/NEA-IAEA symposium on human factors and organisation in NPP maintenance outages: impact on safety

International Nuclear Information System (INIS)

1995-01-01

The sessions of this conference dealt with outage strategy and methods (in Sweden, France and United States), the organisation and management of outages (organisation during refuelling shutdowns in France, safety approaches in France, in the USA, in Canada, in the United Kingdom and in Sweden), case studies and lessons learned (in France, Korea, Sweden, UK, USA), regulatory aspects of outages (UK, Germany, Mexico, France), the development of outage techniques

Risk-based evaluation of Allowed Outage Times (AOTs) considering risk of shutdown

International Nuclear Information System (INIS)

Mankamo, T.; Kim, I.S.; Samanta, P.K.

1992-01-01

When safety systems fail during power operation, Technical Specifications (TS) usually limit the repair within Allowed Outage Time (AOT). If the repair cannot be completed within the AOT, or no AOT is allowed, the plant is required to be shut down for the repair. However, if the capability to remove decay heat is degraded, shutting down the plant with the need to operate the affected decay-heat removal systems may impose a substantial risk compared to continued power operation over a usual repair time. Thus, defining a proper AOT in such situations can be considered as a risk-comparison between the repair in frill power state with a temporarily increased level of risk, and the altemative of shutting down the plant for the repair in zero power state with a specific associated risk. The methodology of the risk-comparison approach, with a due consideration of the shutdown risk, has been further developed and applied to the AOT considerations of residual heat removal and standby service water systems of a boiling water reactor (BWR) plant. Based on the completed work, several improvements to the TS requirements for the systems studied can be suggested

A study on assessment methodology of surveillance test interval and allowed outage time

International Nuclear Information System (INIS)

Che, Moo Seong; Cheong, Chang Hyeon; Lee, Byeong Cheol

1996-07-01

The objectives of this study is the development of methodology by which assessing the optimizes Surveillance Test Interval(STI) and Allowed Outage Time(AOT) using PSA method that can supplement the current deterministic methods and the improvement of Korea nuclear power plants safety. In the first year of this study, the survey about the assessment methodologies, modeling and results performed by domestic and international researches is performed as the basic step before developing the assessment methodology of this study. The assessment methodology that supplement the revealed problems in many other studies is presented and the application of new methodology into the example system assures the feasibility of this method

A study on assessment methodology of surveillance test interval and allowed outage time

Energy Technology Data Exchange (ETDEWEB)

Che, Moo Seong; Cheong, Chang Hyeon; Lee, Byeong Cheol [Seoul Nationl Univ., Seoul (Korea, Republic of)] (and others)

1996-07-15

The objectives of this study is the development of methodology by which assessing the optimizes Surveillance Test Interval(STI) and Allowed Outage Time(AOT) using PSA method that can supplement the current deterministic methods and the improvement of Korea nuclear power plants safety. In the first year of this study, the survey about the assessment methodologies, modeling and results performed by domestic and international researches is performed as the basic step before developing the assessment methodology of this study. The assessment methodology that supplement the revealed problems in many other studies is presented and the application of new methodology into the example system assures the feasibility of this method.

Impact of Co-Channel Interference on the Outage Performance Under Multiple Type II Relay Environments

KAUST Repository

Choi, Seyeong; Alouini, Mohamed-Slim; Nam, Sung Sik

2017-01-01

In this paper, through an exact analysis of the outage probability, we investigate the impact of co-channel interference (CCI) on the outage performance of type II (or user equipment) relay under multiple-relay environments considering the selection combining-based relay selection scheme with the decode-and-forward protocol. We consider the signal to interference plus noise ratio (SINR) over both independent and identically distributed and independent but non-identically distributed fading channels. To fully take into account the effect of CCI, we adopt a more practical parameter such as the CCI coefficient. The major difficulty in the analysis resides in the determination of the statistics of the output SINR. To settle this problem, we first present the general but relatively simplified expressions for the statistics and then the related outage probability in closed-form. Furthermore, to consider more practical scenario, based on the fact that the number of participating relays can be random, we investigate the average outage probability by averaging the number of participating relays.

Impact of Co-Channel Interference on the Outage Performance Under Multiple Type II Relay Environments

KAUST Repository

Choi, Seyeong

2017-11-15

In this paper, through an exact analysis of the outage probability, we investigate the impact of co-channel interference (CCI) on the outage performance of type II (or user equipment) relay under multiple-relay environments considering the selection combining-based relay selection scheme with the decode-and-forward protocol. We consider the signal to interference plus noise ratio (SINR) over both independent and identically distributed and independent but non-identically distributed fading channels. To fully take into account the effect of CCI, we adopt a more practical parameter such as the CCI coefficient. The major difficulty in the analysis resides in the determination of the statistics of the output SINR. To settle this problem, we first present the general but relatively simplified expressions for the statistics and then the related outage probability in closed-form. Furthermore, to consider more practical scenario, based on the fact that the number of participating relays can be random, we investigate the average outage probability by averaging the number of participating relays.

Partner cooperation with decode-and-forward: Closed-form outage analysis and comparison

KAUST Repository

Benjillali, Mustapha

2013-01-01

In this paper, we investigate the outage performance of "partner cooperation" based on opportunistic Decodeand- Forward with constrained partial selection and reactive relaying strategies in dual-hop cooperative Nakagami-m fading links. The source/destination, which is based on the unique knowledge of local channel state information, selects the best relay to increase the chances of cooperation in both uplink and downlink communications when the direct link is also available. After deriving new expressions for the cumulative distribution functions of the variables of interest, the outage probability of the system is obtained in closed-form. We also derive the ε-outage capacity in different particular cases, and the obtained results - when the channel model is reduced to a Rayleigh fading - either are new or correspond to those previously obtained in other works. Simulation results confirm the accuracy of our analysis for a large selection of system and fading parameters and provide a new insight into the design and optimization of cooperative configurations. © 2012 IEEE.

Outage Performance of Decode-and-Forward in Two-Way Relaying with Outdated CSI

KAUST Repository

Hyadi, Amal

2015-01-07

In this paper, we analyze the outage behavior of decode-and-forward relaying in the context of selective two-way cooperative systems. First, a new relay selection metric is proposed to take into consideration both transmission rates and instantaneous link conditions between cooperating nodes. Afterwards, the outage probability of the proposed system is derived for Nakagami-m fading channels in the case when perfect channel state information is available and then extended to the more realistic scenario where the available channel state information (CSI) is outdated due to fast fading. New expressions for the outage probability are obtained, and the impact of imperfect CSI on the performance is evaluated. Illustrative numerical results, Monte Carlo simulations, and comparisons with similar approaches are presented to assess the accuracy of our analytical derivations and confirm the performance gain of the proposed scheme.

Lifetime extension of ageing nuclear power plants. Entering a new era of risk. Report comissionned by Greenpeace

International Nuclear Information System (INIS)

2014-03-01

The abbreviated version of the Greenpeace report on the lifetime extension of aging nuclear power plants - entering a new era of risk - covers the following topics: age of the nuclear power plants in Europe, covered amounts of insurance in Europe in case of a nuclear accident, progress of the ageing of nuclear power plants, and the power up-rating of nuclear reactors. The economy of aged reactors is discussed in connection with the lifetime extension and the liabilities for the aging reactors.

Evaluation of potential severe accidents during Low Power and Shutdown Operations at Grand Gulf, Unit 1. Volume 2, Part 1B: Analysis of core damage frequency from internal events for Plant Operational State 5 during a refueling outage, Main report (Section 10)

International Nuclear Information System (INIS)

Whitehead, D.; Darby, J.; Yakle, J.

1994-06-01

This document contains the accident sequence analysis of internally initiated events for Grand Gulf, Unit 1 as it operates in the Low Power and Shutdown Plant Operational State 5 during a refueling outage. The report documents the methodology used during the analysis, describes the results from the application of the methodology, and compares the results with the results from two full power performed on Grand Gulf. This document, Volume 2, Part 1B, presents chapters Section 10 of this report, Human Reliability Analysis

Ratepayers should not fund IP-2 outage, NY Attorney General says

International Nuclear Information System (INIS)

Anon.

1981-01-01

The New York Attorney General is trying to block Consolidated Edison's effort to pay for an Indian Point nuclear plant outage through the fuel-adjustment clause on the grounds that the utility had repeated system warnings and should have taken action to prevent the leakage of water into the containment building. The utility rejects the assessment of personnel negligence and, blaming equipment failure, plans to replace its heat exchangers. The New York Public Service Commission approved Con Ed's use of the fuel-adjustment clause to pay for replacement power, but agrees that ratepayers should not pay the costs of negligence if the charges are proved. The Attorney General feels that Con Ed could legally challenge a later request for refunds. Other funding possibilities include nuclear-insurance policies or legal action against the equipment manufacturer

On the Required Number of Antennas in a Point-to-Point Large-but-Finite MIMO System: Outage-Limited Scenario

KAUST Repository

Makki, Behrooz

2016-03-22

This paper investigates the performance of the point-To-point multiple-input-multiple-output (MIMO) systems in the presence of a large but finite numbers of antennas at the transmitters and/or receivers. Considering the cases with and without hybrid automatic repeat request (HARQ) feedback, we determine the minimum numbers of the transmit/receive antennas, which are required to satisfy different outage probability constraints. Our results are obtained for different fading conditions and the effect of the power amplifiers efficiency/feedback error probability on the performance of the MIMO-HARQ systems is analyzed. Then, we use some recent results on the achievable rates of finite block-length codes, to analyze the effect of the codewords lengths on the system performance. Moreover, we derive closed-form expressions for the asymptotic performance of the MIMO-HARQ systems when the number of antennas increases. Our analytical and numerical results show that different outage requirements can be satisfied with relatively few transmit/receive antennas. © 1972-2012 IEEE.

Evaluation of potential severe accidents during low power and shutdown operations at Grand Gulf, Unit 1. Volume 5: Analysis of core damage frequency from seismic events for plant operational state 5 during a refueling outage

International Nuclear Information System (INIS)

Budnitz, R.J.; Davis, P.R.; Ravindra, M.K.; Tong, W.H.

1994-08-01

In 1989 the US Nuclear Regulatory Commission (NRC) initiated an extensive program to examine carefully the potential risks during low-power and shutdown operations. The program included two parallel projects, one at Sandia National Laboratories studying a boiling water reactor (Grand Gulf), and the other at Brookhaven National Laboratory studying a pressurized water reactor (Surry Unit 1). Both the Sandia and Brookhaven projects have examined only accidents initiated by internal plant faults---so-called ''internal initiators.'' This project, which has explored the likelihood of seismic-initiated core damage accidents during refueling outage conditions, is complementary to the internal-initiator analyses at Brookhaven and Sandia. This report covers the seismic analysis at Grand Gulf. All of the many systems modeling assumptions, component non-seismic failure rates, and human effort rates that were used in the internal-initiator study at Grand Gulf have been adopted here, so that the results of the study can be as comparable as possible. Both the Sandia study and this study examine only one shutdown plant operating state (POS) at Grand Gulf, namely POS 5 representing cold shutdown during a refueling outage. This analysis has been limited to work analogous to a level-1 seismic PRA, in which estimates have been developed for the core-damage frequency from seismic events during POS 5. The results of the analysis are that the core-damage frequency for earthquake-initiated accidents during refueling outages in POS 5 is found to be quite low in absolute terms, less than 10 -7 /year

Utility Test Results of a 2-Megawatt, 10-Second Reserve-Power System

Energy Technology Data Exchange (ETDEWEB)

BALL,GREG J.; NORRIS,BENJAMIN L.

1999-10-01

This report documents the 1996 evaluation by Pacific Gas and Electric Company of an advanced reserve-power system capable of supporting 2 MW of load for 10 seconds. The system, developed under a DOE Cooperative Agreement with AC Battery Corporation of East Troy, Wisconsin, contains battery storage that enables industrial facilities to ''ride through'' momentary outages. The evaluation consisted of tests of system performance using a wide variety of load types and operating conditions. The tests, which included simulated utility outages and voltage sags, demonstrated that the system could provide continuous power during utility outages and other disturbances and that it was compatible with a variety of load types found at industrial customer sites.

Limiting the impact of recent outage experience in a midsize university reactor environment

International Nuclear Information System (INIS)

Vernetson, W.G.

1996-01-01

The University of Florida Training Reactor (UFTR) is a light-water-cooled, graphite- and light-water-moderated, modified Argonaut-type reactor licensed to operate at steady-state power levels up to 100 kW. The UFTR continues to utilize high-enriched materials test reactor-type fuel in a piping circuit type of system versus the more familiar pool reactor design. Though somewhat limited for research and service, the UFTR is a valuable educational facility. Despite its relatively low power level, the two-slab core configuration provides a peak thermal flux near 2 x 10 12 n/cm 2 · s; in addition, other modifications and experimental adaptations have been implemented in the 36-yr history of the facility to enhance the potential of the facility for diverse types of unique educational usage. Its small physical size in a loop configuration makes it a good teaching tool, but it can also be associated with unique maintenance problems, as in this case. The mission of the UFTR is to serve regional needs for access to quality reactor usage in a variety of areas to support educational and training needs as well as research and service, including public information about nuclear energy. As the only nonpower reactor in the state of Florida in affiliation with an established and diverse nuclear and radiological engineering department, it has a strong role to play in education, training, research, and service, especially the former. As a result of its unique position, the facility has been quite successful in its mission. With so much educational usage scheduled, sometimes for classes arriving from 100 miles away, it is important to avoid unexpected outages as well as unexpectedly lengthy outages. Such planning usually is successful and has allowed the RFTR to build a clientele of more than four dozen regular educational users, although events in 1995 could have undetermined this effort

Proper Use of Candles During a Power Outage

Centers for Disease Control (CDC) Podcasts

Home fires are a threat after a natural disaster and fire trucks may have trouble getting to your home. If the power is out, use flashlights or other battery-powered lights if possible, instead of candles.

An opportunity for capacity up-rating of 1000 MW steam turbine plant in Kozloduy NPP

International Nuclear Information System (INIS)

Popov, D.

2005-01-01

In connection with earlier and forced decommissioning of the Kozloduy NPP units 1 - 4, an alternative has to be found in order to substitute these capacities. As a reasonable options, capacity up-rating of 1000 MW steam turbine plants without nuclear reactor thermal capacity increase, is investigated in the present study. The cooling water for these units is delivered by Danube river. The cooling water temperatures substantially decrease during the winter months. These changes create an opportunity for steam back end pressure reduction. It was found that when the cooling water temperature decreases from 15 0 C to 3 0 C, the steam back end pressure is on the decrease of from 3.92 kPa to 2.3 kPa. As a result capacity of the plant could be raised up to 50 MW without any substantial equipment and systems change

Short term Braking Capability during Power Interruptions for Integrated Matrix Converter-Motor Drives

DEFF Research Database (Denmark)

Klumpner, Christian; Blaabjerg, Frede

2002-01-01

attractive. Sinusoidal input currents and bi-directional power flow are other advantages of the matrix converter but it is less immune to power grid disturbances compared to a standard ASD. In hoisting applications, short-term braking capability during a power outage is needed until the mechanical brake...... engages or to perform more effective a combined braking.This paper proposes a new method to provide short-term braking capability during a power outage for matrix converters. A braking chopper is needed in the clamp circuit, which allows for a drastically reduction of the capacitor size. The power flow...

A novel fusion methodology to bridge GPS outages for land vehicle positioning

International Nuclear Information System (INIS)

Chen, Wei; Li, Xu; Song, Xiang; Xu, Qimin; Li, Bin; Song, Xianghui

2015-01-01

Many intelligent transportation system applications require accurate, reliable, and continuous vehicle position information whether in open-sky environments or in Global Positioning System (GPS) denied environments. However, there remains a challenging task for land vehicles to achieve such positioning performance using low-cost sensors, especially microelectromechanical system (MEMS) sensors. In this paper, a novel and cost-effective fusion methodology to bridge GPS outages is proposed and applied in the Inertial Navigation System (INS)/GPS/ compass integrated positioning system. In the implementation of the proposed methodology, a key data preprocessing algorithm is first developed to eliminate the noise in inertial sensors in order to provide more accurate information for subsequent modeling. Then, a novel hybrid strategy incorporating the designed autoregressive model (AR model)-based forward estimator (ARFE) with Kalman filter (KF) is presented to predict the INS position errors during GPS outages. To verify the feasibility and effectiveness of the proposed methodology, real road tests with various scenarios were performed. The proposed methodology illustrates significant improvement in positioning accuracy during GPS outages. (paper)

Optimized Power Allocation and Relay Location Selection in Cooperative Relay Networks

Directory of Open Access Journals (Sweden)

Jianrong Bao

2017-01-01

Full Text Available An incremental selection hybrid decode-amplify forward (ISHDAF scheme for the two-hop single relay systems and a relay selection strategy based on the hybrid decode-amplify-and-forward (HDAF scheme for the multirelay systems are proposed along with an optimized power allocation for the Internet of Thing (IoT. Given total power as the constraint and outage probability as an objective function, the proposed scheme possesses good power efficiency better than the equal power allocation. By the ISHDAF scheme and HDAF relay selection strategy, an optimized power allocation for both the source and relay nodes is obtained, as well as an effective reduction of outage probability. In addition, the optimal relay location for maximizing the gain of the proposed algorithm is also investigated and designed. Simulation results show that, in both single relay and multirelay selection systems, some outage probability gains by the proposed scheme can be obtained. In the comparison of the optimized power allocation scheme with the equal power allocation one, nearly 0.1695 gains are obtained in the ISHDAF single relay network at a total power of 2 dB, and about 0.083 gains are obtained in the HDAF relay selection system with 2 relays at a total power of 2 dB.

Power Recapture and Power Uprate in NPPS with Process Data Reconciliation in Accordance with VDI 2048

International Nuclear Information System (INIS)

Magnus Langenstein

2006-01-01

The determination of the thermal reactor power is traditionally done by establishing the heat balance for a boiling water reactor (BWR) at the interface of reactor control volume and heat cycle for a pressurized water reactor (PWR) at the interface of the steam generator control volume and turbine island on the secondary side The uncertainty of these traditional methods is not easy to determine and it can be in the range of several percent. Technical and legal regulations (e.g. 10CFR50) cover an estimated instrumentation error of up to 2% by increasing the design thermal reactor power for emergency analysis to 102% of the licensed thermal reactor power. Basically, the licensee has the duty to warrant at any time operation inside the analysed region for thermal reactor power. This is normally done by keeping the indicated reactor power at the licensed 100% value. A better way is to use a method which allows a continuous warranty evaluation. The quantification of the level of fulfillment of this warranty is only achievable by a method which is independent of single measurements accuracies results in a certified quality of single process values and for the total heat cycle analysis leads to complete results including 2-sigma deviation especially for thermal reactor power This method, which is called 'process data reconciliation based on VDI 2048 guideline', is presented here [1, 2]. The method allows to determine the true process parameters with a statistical probability of 95%, by considering closed material, mass- and energy balances following the Gaussian correction principle. The amount of redundant process information and complexity of the process improves the final results. This represents the most probable state of the process with minimized uncertainty according to VDI 2048. Hence, calibration and control of the thermal reactor power are possible with low effort but high accuracy and independent of single measurement accuracies. Furthermore, VDI 2048 describes

Methodology if inspections to carry out the nuclear outages model; Metodologia de inspeccciones para cumplir el modelo de paradas nucleares

Energy Technology Data Exchange (ETDEWEB)

Aycart, J.; Mortenson, S.; Fourquet, J. M.

2005-07-01

Before the nuclear generation industry was deregulated in the United States, refueling and maintenance outages in nuclear power plants usually lasted orotund 100 days. After deregulation took effect, improved capability factors and performances became more important. As a result, it became essential to reduce the critical path time during the outage, which meant that activities that had typically been done in series had to be executed in parallel. The new outage model required the development of new tools and new processes, The 360-degree platform developed by GE Energy has made it possible to execute multiple activities in parallel. Various in-vessel visual inspection (IVVI) equipments can now simultaneously perform inspections on the pressurized reactor vessel (RPV) components. The larger number of inspection equipments in turn results in a larger volume of data, with the risk of increasing the time needed for examining them and postponing the end of the analysis phase, which is critical for the outage. To decrease data analysis times, the IVVI Digitalisation process has been development. With this process, the IVVI data are sent via a high-speed transmission line to a site outside the Plant called Center of Excellence (COE), where a team of Level III experts is in charge of analyzing them. The tools for the different product lines are being developed to interfere with each other as little as possible, thus minimizing the impact of the critical path on plant refueling activities. Methods are also being developed to increase the intervals between inspection. In accordance with the guidelines of the Boiling Water Reactor Vessel and Internals project (BWRVIP), the intervals between inspections are typically longer if ultrasound volumetric inspections are performed than if the scope is limited to IVVI. (Author)

Outage performance of Decode-and-Forward partial selection in Nakagami-m fading channels

KAUST Repository

Benjillali, Mustapha

2010-01-01

In this paper, we investigate the outage performance of Decode-and-Forward with partial selection relaying in dualhop cooperative Nakagami-m fading links. The source, based on the unique knowledge of local first hop channel state information, selects the best relay to increase the chances of successful decoding and hence the possibility of cooperation when the direct link is also available. After deriving the exact distribution of the sum of two gamma variates with the same shape parameter, the outage probability of the system-with and without the direct link-is obtained in closed-form. We also derive the ε-outage capacity in different particular cases, and the obtained results- when the channel model is reduced to a Rayleigh fading-are either new or correspond to those previously obtained in other works. Simulation results confirm the accuracy of our analysis for a large selection of system and fading parameters. © 2009 IEEE.

Configuration control during plant outages. A review of operating experience

Energy Technology Data Exchange (ETDEWEB)

Peinador Veira, Miguel; El Kanbi, Semir [European Commission Joint Research Centre, Petten (Netherlands). Inst. for Energy and Transport; Stephan, Jean-Luc [Institut de Radioprotection et de Surete Nucleaire (IRSN), Fontenay-aux-Roses (France); Martens, Johannes [Gesellschaft fuer Anlagen- und Reaktorsicherheit (GRS) gGmbH, Koeln (Germany)

2015-03-15

After the occurrence of several significant events in nuclear power plants during shut-down modes of operation in the eighties, and from the results of probabilistic safety assessments completed in the nineties, it was clear that risk from low power and shutdown operational modes could not be neglected and had to be addressed by appropriate safety programs. A comprehensive review of operating experience from the last ten years has been conducted by the Joint Research Centre with the objective of deriving lessons learned and recommendations useful for nuclear regulatory bodies and utilities alike. This paper is focused on one particular challenge that any nuclear plant faces whenever it plans its next outage period: how to manage the configuration of all systems under a complex environment involving numerous concurrent activities, and how to make sure that systems are returned to their valid configuration before the plant resumes power operation. This study highlights the importance of conveying accurate but synthesized information on the status of the plant to the operators in the main control room. Many of the lessons learned are related to the alarm display in the control room and to the use of check lists to control the status of systems. Members of the industry and safety authorities may now use these recommendations and lessons learned to feed their own operating experience feedback programs, and check their applicability for specific sites.

Shortened outage duration and increased safety with head assembly upgrade packages

International Nuclear Information System (INIS)

Leanne, M.; Lisien, P.E.; Plute, K.; Duran, J.

2007-01-01

To significantly reduce outage critical path duration and personnel radiation exposure, and to increase personnel safety, Westinghouse Electric Co., LLC has designed and installed upgrades to the existing head assemblies of operating pressurized water reactors. These upgrades are known as Head Assembly Upgrade Packages (HAUPs) or Simplified Head Assemblies (SHAs). Custom configurations are created from a set of standard elements to optimize the design for each unique containment, head assembly configuration, and licensing basis. Two primary options are available for implementation: a full HAUP or targeted component and system upgrades. Plants may achieve much of the outage savings, dose reduction, and safety improvements even with a more limited hardware scope. A range of improvements can be offered from integral missile shields, to redesigned duct work, radiation shields, and cable layout and connection optimization. The hardware changes are customized to target the scope that adds the most value for a given plant. While combining upgrades with a reactor vessel head (RVH) replacement adds some flexibility, it is not necessary. Some plants have chosen to implement targeted upgrades prior to a replacement RVH outage and then complete the remainder of the full HAUP during the replacement RVH outage. Three-dimensional computer aided design tools are used in the conceptual and detailed design phases to identify and avoid interferences between existing and replacement plant components. State-of-the-art computational fluid dynamics models for control drive mechanism (CDM) cooling systems are used to demonstrate the ability to maintain or improve the original design performance while greatly simplifying the disassembly/re-assembly activities. Likewise, state-of-the-art finite element analysis methods allow optimization of structural components while meeting code limits for design basis accident conditions. (authors)

Outage performance of opportunistic two-way amplify-and-forward relaying with outdated channel state information

KAUST Repository

Hwang, Kyusung

2013-09-01

In this paper, we study the outage performance of an amplify-and-forward (AF)-based two-way relaying (TWR) system with multiple relays where a single relay selection is performed based on outdated channel state information (CSI). Specifically, we propose a single relay selection scheme in AF-based TWR system under outdated CSI conditions. With this policy, we offer a statistical analysis of the signal-to-noise ratio per hop and analyze the outage probability with asymmetric outage thresholds based on CSI-assisted AF protocol. Additionally, we provide the exact and asymptotic expressions based on the provided statistical/joint statistical analyses of a dual-hop AF transmission. Finally, we verify our analytical results with some selected computer-based simulation results. © 1972-2012 IEEE.

Proper Use of Candles During a Power Outage

Centers for Disease Control (CDC) Podcasts

2006-08-10

Home fires are a threat after a natural disaster and fire trucks may have trouble getting to your home. If the power is out, use flashlights or other battery-powered lights if possible, instead of candles.  Created: 8/10/2006 by Emergency Communications System.   Date Released: 8/20/2008.

Start-up of Cirus after refurbishment outage and observations during approach to criticality

International Nuclear Information System (INIS)

Singh, Tej; Singh, Kanchhi; Sengupta, S.N.

2004-10-01

The report presents various physics related aspects of the startup of Cirus reactor after the prolonged refurbishment outage. The special nuclear instrumentation scheme adopted to ensure safe startup of the reactor is described. Salient observations made and physics measurements carried out during various approaches to criticality are covered. One of the significant observations concerned a major reactivity anomaly during the approach to criticality. After due investigations the cause of the anomaly was attributed to the inadvertent wetting of the graphite reflector which houses the reactor regulating and protection system ion chambers. The report also includes salient observations during raising of reactor power to high levels. The wet reflector also resulted in a significant difference measured between the thermal and neutronic power of the reactor. In view of the reactivity anomaly, the core reactivity variation with time was closely followed and compared with computations. As expected the reactivity anomaly reduced gradually with time. (author)

A study on assessment methodology of surveillance test interval and allowed outage time

Energy Technology Data Exchange (ETDEWEB)

Chung, Chang Hyun; You, Young Woo; Cho, Jae Seon; Huh, Chang Wook; Kim, Do Hyoung; Kim, Ju Youl; Kim, Yoon Ik; Yang, Hui Chang; Park, Kang Min [Seoul National Univ., Seoul (Korea, Republic of)

1998-03-15

The objectives of this study is the development of methodology by which assesses the optimization of Surveillance Test Internal(STI) and Allowed Outage Time(AOT) using PSA method that can supplement the current deterministic methods and the improvement of Korean nuclear power plant safety. In this study, the survey about the assessment methodologies, modelings and results performed by domestic and international researches are performed as the basic step before developing the assessment methodology of this study. The assessment methodology that supplement the revealed problems in many other studies is presented and the application of new methodology into the example system assures the feasibility of this method. The sensitivity analyses about the failure factors of the components are performed in the bases of the and AOT is quantified. And the reliability assessment methodology about the diesel generator is reviewed and applied to the PSA code. The qualitative assessment for the STI/AOR of RPS/ESFAS assured safety the most important system in the nuclear power plant are performed.

Integrated services as the key to the optimisation of refueling outages

International Nuclear Information System (INIS)

Ortega, Juan; Gonzalez, Roberto; Gutierrez, Jose E.

2010-01-01

Refueling outages at nuclear power plants are subject to demanding improvement criteria in each and every one of the activities scheduled. The management of activities on the refueling floor, including the phases of opening and closing of the reactor vessel and associated tasks relating to the reactor internals, the unloading, loading and management of the irradiated fuel and activities requested for the in-service inspection of essential primary circuit components, are interventions that have an impact on the refueling critical path and whose overall integration allows for significant optimization of the entire management of this fundamental refueling activity. For several years now, ENUSA, as the company specializing in irradiated fuel services, TECNATOM as the company responsible for the in-service inspection of critical primary side components and Westinghouse as the technology provider and specialist in the supply of plant support services, have together formed a solid working team offering this integrated refueling service to the Spanish plants. Today, the new and heightened demands regarding the training and specialization of the personnel participating in refueling outages, the need to consider contingencies in the activities scheduled and the objectives relating to the ALARA concept and safe operations require that this service include new activities providing synergies and leading to higher levels of commitment to excellence. This paper will present the service model developed, the most significant activities integrated in the service and the advantages and milestones achieved and reached during this period, compared to the conventional distributed functions model. Likewise, an analysis will be made of the new challenges that are being addressed, with a view to bringing about a more global integration. (authors)

Human errors and work performance in a nuclear power plant control room: associations with work-related factors and behavioral coping

International Nuclear Information System (INIS)

Kecklund, Lena Jacobsson; Svenson, Ola

1997-01-01

The present study investigated the relationships between the operator's appraisal of his own work situation and the quality of his own work performance as well as self-reported errors in a nuclear power plant control room. In all, 98 control room operators from two nuclear power units filled out a questionnaire and several diaries during two operational conditions, annual outage and normal operation. As expected, the operators reported higher work demands in annual outage as compared to normal operation. In response to the increased demands, the operators reported that they used coping strategies such as increased effort, decreased aspiration level for work performance quality and increased use of delegation of tasks to others. This way of coping does not reflect less positive motivation for the work during the outage period. Instead, the operators maintain the same positive motivation for their work, and succeed in being more alert during morning and night shifts. However, the operators feel less satisfied with their work result. The operators also perceive the risk of making minor errors as increasing during outage. The decreased level of satisfaction with work result during outage is a fact despite the lowering of aspiration level for work performance quality during outage. In order to decrease relative frequencies for minor errors, special attention should be given to reduce work demands, such as time pressure and memory demands. In order to decrease misinterpretation errors special attention should be given to organizational factors such as planning and shift turnovers in addition to training. In summary, the outage period seems to be a significantly more vulnerable window in the management of a nuclear power plant than the normal power production state. Thus, an increased focus on the outage period and human factors issues, addressing the synergetic effects or work demands, organizational factors and coping resources is an important area for improvement of

Cost of Lightning Strike Related Outages of Visual Navigational Aids at Airports in the United States

Science.gov (United States)

Rakas, J.; Nikolic, M.; Bauranov, A.

2017-12-01

Lightning storms are a serious hazard that can cause damage to vital human infrastructure. In aviation, lightning strikes cause outages to air traffic control equipment and facilities that result in major disruptions in the network, causing delays and financial costs measured in the millions of dollars. Failure of critical systems, such as Visual Navigational Aids (Visual NAVAIDS), are particularly dangerous since NAVAIDS are an essential part of landing procedures. Precision instrument approach, an operation utilized during the poor visibility conditions, utilizes several of these systems, and their failure leads to holding patterns and ultimately diversions to other airports. These disruptions lead to both ground and airborne delay. Accurate prediction of these outages and their costs is a key prerequisite for successful investment planning. The air traffic management and control sector need accurate information to successfully plan maintenance and develop a more robust system under the threat of increasing lightning rates. To analyze the issue, we couple the Remote Monitoring and Logging System (RMLS) database and the Aviation System Performance Metrics (ASPM) databases to identify lightning-induced outages, and connect them with weather conditions, demand and landing runway to calculate the total delays induced by the outages, as well as the number of cancellations and diversions. The costs are then determined by calculating direct costs to aircraft operators and costs of passengers' time for delays, cancellations and diversions. The results indicate that 1) not all NAVAIDS are created equal, and 2) outside conditions matter. The cost of an outage depends on the importance of the failed system and the conditions that prevailed before, during and after the failure. The outage that occurs during high demand and poor weather conditions is more likely to result in more delays and higher costs.

Outage performance of reactive cooperation in Nakagami-m fading channels

KAUST Repository

Benjillali, Mustapha; Alouini, Mohamed-Slim

2010-01-01

In this paper, we investigate the outage performance of Decode-and-Forward with reactive relaying in dual-hop cooperetive Nakagaml-m fading links. The destination, based on the umque knowledge of local second hop channel state information, selects

Fuel Cells for Backup Power in Telecommunications Facilities (Fact Sheet)

Energy Technology Data Exchange (ETDEWEB)

2009-04-01

Telecommunications providers rely on backup power to maintain a constant power supply, to prevent power outages, and to ensure the operability of cell towers, equipment, and networks. The backup power supply that best meets these objectives is fuel cell technology.

Evaluating system reliability and targeted hardening strategies of power distribution systems subjected to hurricanes

International Nuclear Information System (INIS)

Salman, Abdullahi M.; Li, Yue; Stewart, Mark G.

2015-01-01

Over the years, power distribution systems have been vulnerable to extensive damage from hurricanes which can cause power outage resulting in millions of dollars of economic losses and restoration costs. Most of the outage is as a result of failure of distribution support structures. Over the years, various methods of strengthening distribution systems have been proposed and studied. Some of these methods, such as undergrounding of the system, have been shown to be unjustified from an economic point of view. A potential cost-effective strategy is targeted hardening of the system. This, however, requires a method of determining critical parts of a system that when strengthened, will have greater impact on reliability. This paper presents a framework for studying the effectiveness of targeted hardening strategies on power distribution systems subjected to hurricanes. The framework includes a methodology for evaluating system reliability that relates failure of poles and power delivery, determination of critical parts of a system, hurricane hazard analysis, and consideration of decay of distribution poles. The framework also incorporates cost analysis that considers economic losses due to power outage. A notional power distribution system is used to demonstrate the framework by evaluating and comparing the effectiveness of three hardening measures. - Highlight: • Risk assessment of power distribution systems subjected to hurricanes is carried out. • Framework for studying effectiveness of targeted hardening strategies is presented. • A system reliability method is proposed. • Targeted hardening is cost effective for existing systems. • Economic losses due to power outage should be considered for cost analysis.

Outage Probability Minimization for Energy Harvesting Cognitive Radio Sensor Networks

Directory of Open Access Journals (Sweden)

Fan Zhang

2017-01-01

Full Text Available The incorporation of cognitive radio (CR capability in wireless sensor networks yields a promising network paradigm known as CR sensor networks (CRSNs, which is able to provide spectrum efficient data communication. However, due to the high energy consumption results from spectrum sensing, as well as subsequent data transmission, the energy supply for the conventional sensor nodes powered by batteries is regarded as a severe bottleneck for sustainable operation. The energy harvesting technique, which gathers energy from the ambient environment, is regarded as a promising solution to perpetually power-up energy-limited devices with a continual source of energy. Therefore, applying the energy harvesting (EH technique in CRSNs is able to facilitate the self-sustainability of the energy-limited sensors. The primary concern of this study is to design sensing-transmission policies to minimize the long-term outage probability of EH-powered CR sensor nodes. We formulate this problem as an infinite-horizon discounted Markov decision process and propose an ϵ-optimal sensing-transmission (ST policy through using the value iteration algorithm. ϵ is the error bound between the ST policy and the optimal policy, which can be pre-defined according to the actual need. Moreover, for a special case that the signal-to-noise (SNR power ratio is sufficiently high, we present an efficient transmission (ET policy and prove that the ET policy achieves the same performance with the ST policy. Finally, extensive simulations are conducted to evaluate the performance of the proposed policies and the impaction of various network parameters.

10 CFR 501.191 - Use of natural gas or petroleum for certain unanticipated equipment outages and emergencies...

Science.gov (United States)

2010-01-01

... 10 Energy 4 2010-01-01 2010-01-01 false Use of natural gas or petroleum for certain unanticipated... Natural Gas or Petroleum for Emergency and Unanticipated Equipment Outage Purposes § 501.191 Use of natural gas or petroleum for certain unanticipated equipment outages and emergencies defined in section...

Donald C. Cook Nuclear Power Plant, Unit 1. Annual operating report for 1976

International Nuclear Information System (INIS)

1977-01-01

The unit was paralleled to the grid 83.1 percent of the time and 7,073,200 MWH gross was generated. There were six scheduled outages and 14 forced outages/load reductions. Information is presented concerning operations, shutdowns, power reductions, inservice maintenance, personnel radiation exposures, fuel history, and facility changes

A heuristic model for risk and cost impacts of plant outage maintenance schedule

International Nuclear Information System (INIS)

Mohammad Hadi Hadavi, S.

2009-01-01

Cost and risk are two major competing criteria in maintenance optimization problems. If a plant is forced to shutdown because of accident or fear of accident happening, beside loss of revenue, it causes damage to the credibility and reputation of the business operation. In this paper a heuristic model for incorporating three compelling optimization criteria (i.e., risk, cost, and loss) into a single evaluation function is proposed. Such a model could be used in any evaluation engine of outage maintenance schedule optimizer. It is attempted to make the model realistic and to address the ongoing challenges facing a schedule planner in a simple and commonly understandable fashion. Two simple competing schedules for the NPP feedwater system are examined against the model. The results show that while the model successfully addresses the current challenges for outage maintenance optimization, it properly demonstrates the dynamics of schedule in regards to risk, cost, and losses endured by maintenance schedule, particularly when prolonged outage and lack of maintenance for equipments in need of urgent care are of concern.

Outage and ser performance of spectrum sharing system with TAS/MRC

KAUST Repository

Khan, Fahd Ahmed

2013-06-01

Capacity of the secondary network degrades due to the interference constraint from the primary network. The secondary network capacity can be enhanced by means of spatial diversity, that can be achieved by adding multiple antennas on the terminals. In this paper, the performance of a multiple-input multiple-output (MIMO) secondary link with transmit antenna selection (TAS) at the transmitter and maximum ratio combining (MRC) at the receiver is analysed. A peak transmit power constraint is considered in addition to the interference power constraint. For a Rayleigh faded channel, closed-form expression for the outage probability of a MIMO cognitive system (MIMO-CS) with TAS/MRC is derived. In addition, closed-form expressions of the moment generating function and the symbol error rate are also obtained. The performance of this system is analyzed for asymptotic regimes and it is shown that TAS/MRC in a MIMO-CS achieves a generalized diversity order of nTnR, where nT and nR are the number of transmit and receive antennas, respectively. Numerical results are also presented to corroborate the derived analytical results. © 2013 IEEE.

The IAEA power reactor information system - PRIS

International Nuclear Information System (INIS)

Laue, H.J.; Qureshi, A.; Skjoeldebrand, R.; White, D.

1983-01-01

The IAEA Power Reactor Information System, PRIS, is based on a collection of basic design data and operating experience data which the IAEA started in 1970. PRIS is used for annual publications on 'Power Reactors in Member States', 'Operating Experience with Nuclear Power Stations in Member States', which gives annual operating information for individual plants, and a 'Performance Analysis Report' summarizing each year's and earlier experience. Since 1973 information has been collected in a systematic manner on significant plant outages (= more than 10 full power hours). There is now information on more than 10,000 outages in the system which permits some conclusions to be drawn both in regard to individual plants and to categories of plants on the significance of different outage reasons and different types of equipment failures. PRIS has not been intended to be a component reliability information system as an international data collection must stop short of the level of detail which would be needed for that purpose. The objectives of PRIS have been to provide a factual background for assumptions on parameters which are essential for economic evaluations and for systems operation planning (load factor and availability). The outage information does, however, lend itself to conclusions about generic problems in different categories of plants and it can be used by an individual operator to find other plants where information about particular problems can be obtained. It would also now be possible to use PRIS for setting availability goals based on experience and not only on theoretical design considerations. The paper demonstrates the conclusions which can be drawn from 662 reactor years of operation of light and heavy water pressurized reactors and 390 reactor years of boiling water reactors and, in particular, the role that the main heat removal system and its components have played in the equipment failure category

Wind Power Plant Voltage Stability Evaluation: Preprint

Energy Technology Data Exchange (ETDEWEB)

Muljadi, E.; Zhang, Y. C.

2014-09-01

Voltage stability refers to the ability of a power system to maintain steady voltages at all buses in the system after being subjected to a disturbance from a given initial operating condition. Voltage stability depends on a power system's ability to maintain and/or restore equilibrium between load demand and supply. Instability that may result occurs in the form of a progressive fall or rise of voltages of some buses. Possible outcomes of voltage instability are the loss of load in an area or tripped transmission lines and other elements by their protective systems, which may lead to cascading outages. The loss of synchronism of some generators may result from these outages or from operating conditions that violate a synchronous generator's field current limit, or in the case of variable speed wind turbine generator, the current limits of power switches. This paper investigates the impact of wind power plants on power system voltage stability by using synchrophasor measurements.

Outage probability of dual-hop partial relay selection with feedback delay in the presence of interference

KAUST Repository

Al-Qahtani, Fawaz S.

2011-09-01

In this paper, we investigate the outage performance of a dual-hop relaying systems with partial relay selection and feedback delay. The analysis considers the case of Rayleigh fading channels when the relaying station as well as the destination undergo mutually independent interfering signals. Particularly, we derive the cumulative distribution function (c.d.f.) of a new type of random variable involving sum of multiple independent exponential random variables, based on which, we present closed-form expressions for the exact outage probability of a fixed amplify-and-forward (AF) and decode-and-forward (DF) relaying protocols. Numerical results are provided to illustrate the joint effect of the delayed feedback and co-channel interference on the outage probability. © 2011 IEEE.

Power system relaying

CERN Document Server

Horowitz, Stanley H; Niemira, James K

2013-01-01

The previous three editions of Power System Relaying offer comprehensive and accessible coverage of the theory and fundamentals of relaying and have been widely adopted on university and industry courses worldwide. With the third edition, the authors have added new and detailed descriptions of power system phenomena such as stability, system-wide protection concepts and discussion of historic outages. Power System Relaying, 4th Edition continues its role as an outstanding textbook on power system protection for senior and graduate students in the field of electric power engineering and a refer

Simulation of the steady state of the Laguna Verde Nuclear power station at full power (1931 MWt and 2027 Mwt) with the SCDAPSIM code

International Nuclear Information System (INIS)

Amador G, R.; Nunez C, A.; Mateos, E. del A.

2001-01-01

This document describes two models developed for the Laguna Verde Nuclear Power Station (LVNPP) using SCDAPSIM computer code. These models represent the LVNPP in normal operation with a nominal power of 1931 MWt and power uprate conditions of 2027 MWt. The steady states obtained by means of these models comply with the criteria established by the ANSI/ANS-3.5-1985 for nuclear power plant simulators. This criteria has been applied to the models of the LVNPP developed by CNSNS in want of some international accepted criteria for ''Best Estimation'' computer codes. These models will be the bases to carry out studies of validation of the own models as well as the analysis of diverse scenarios that evolve to a severe accident. (Author)

Siemens capabilities to perform detailed fuel inspections during short outages

International Nuclear Information System (INIS)

Knecht, K.; Reparaz, A.

1999-01-01

Fuel inspection data are used to support development activities such as corrosion resistant cladding and advanced fuel assembly designs that will reach higher burnups. Increased inspection efforts are necessary to optimize fuel management and performance strategies. Additionally, there is an increasing trend to reduce outage time in Germany and abroad. Siemens has recently developed several timesaving systems for rapid inspection of fuel assemblies and core components. Siemens' focus in developing these systems has been to obtain data in reduced reactor outage time while increasing both the volume and the quality of the measured data. Mast sipping for PWRs is used for identifying leaking fuel assemblies and allows early detection of leaks during downloading of the fuel assemblies from the reactor. An In-Core sipping system for BWRs based on a hood technique to allow testing a full core within 16 hours is under development. (authors)

Improved Adaptive Droop Control Design for Optimal Power Sharing in VSC-MTDC Integrating Wind Farms

Directory of Open Access Journals (Sweden)

Xiaohong Ran

2015-07-01

Full Text Available With the advance of insulated gate bipolar transistor (IGBT converters, Multi-Terminal DC (MTDC based on the voltage-source converter (VSC has developed rapidly in renewable and electric power systems. To reduce the copper loss of large capacity and long distance DC transmission line, an improved droop control design based on optimal power sharing in VSC-MTDC integrating offshore wind farm is proposed. The proposed approach provided a calculation method for power-voltage droop coefficients under two different scenarios either considering local load or not. The available headroom of each converter station was considered as a converter outage, to participate in the power adjustment according to their ability. A four-terminal MTDC model system including two large scale wind farms was set up in PSCAD/EMTDC. Then, the proposed control strategy was verified through simulation under the various conditions, including wind speed variation, rectifier outage and inverter outage, and a three-phase short-circuit of the converter.

When does unreliable grid supply become unacceptable policy? Costs of power supply and outages in rural India

International Nuclear Information System (INIS)

Harish, Santosh M.; Morgan, Granger M.; Subrahmanian, Eswaran

2014-01-01

Despite frequent blackouts and brownouts, extension of the central grid remains the Indian government's preferred strategy for the country's rural electrification policy. This study reports an assessment that compares grid extension with distributed generation (DG) alternatives, based on the subsidies they will necessitate, and costs of service interruptions that are appropriate in the rural Indian context. Using cross-sectional household expenditure data and region fixed-effects models, average household demand is estimated. The price elasticity of demand is found to be in the range of −0.3 to −0.4. Interruption costs are estimated based on the loss of consumer surplus due to reduced consumption of electric lighting energy that results from intermittent power supply. Different grid reliability scenarios are simulated. Despite the inclusion of interruption costs, standalone DG does not appear to be competitive with grid extension at distances of less than 17 km. However, backing up unreliable grid service with local DG plants is attractive when reliability is very poor, even in previously electrified villages. Introduction of energy efficient lighting changes these economics, and the threshold for acceptable grid unreliability significantly reduces. A variety of polices to promote accelerated deployment and the wider adoption of improved end-use efficiency, warrant serious consideration. - Highlights: • We question the reliance on conventional grid in rural electricity supply in India. • Alternatives compared through government subsidies and consumer interruption costs. • Interruption costs are estimated based on loss of consumer surplus due to outages. • Augmenting unreliable grid with local biomass or diesel based backups preferable. • With efficient lighting, standalone biomass plants are optimal at very low distances

A good advertisement for hydro power

International Nuclear Information System (INIS)

Wood, J.

1999-01-01

The generation of hydroelectric power in Iceland continues to be a thriving business. Between 1996 and 2000, Landsvirkjun will increase its supply to customers by 50%: the additional power will be used by the expanding energy-intensive heavy industries. Although prices for construction and operation of industrial plant in Iceland are not always the lowest, the quality is said to be exceptionally high and this attracts outside investors. Iceland continues to uprate old generating plant and build new. Through Landsvirkjun all of Iceland's electricity comes from renewable sources: diesel and gas appear to have little future in Iceland. Nevertheless, Landsvirkjun does not have a total monopoly: permits for new developments are issued to suitable applicants and competition is likely to increase. (UK)

Flexible transfer limits in an open power market - Congestion versus risk of interruption

Energy Technology Data Exchange (ETDEWEB)

Warland, Geir

1999-07-01

Traditionally, power systems have been operated by deterministic criteria which tend to provide conservative security limits and will be inflexible and insensitive to changes in outage probabilities or market demands in a deregulated power system. This thesis introduces a new approach to power system operation in which the determination of operating limits for critical transmission lines or corridors is presented as a multiobjective decision problem, including risk assessment. Two objectives are included: (1) minimization of operating cost and (2) obtaining a secure operating level. The operating costs included are congestion costs, interruption costs and the costs of corrective or preventive actions to enhance security. In modelling uncertainties, a fuzzy model for the amount of load lost due to outages is presented. It includes the subjective uncertainty in the assessment of the amount of load lost, considering weather dependency of outage probabilities. There are four main conclusions: (1) The approach is flexible and sensitive to changes in outage probabilities and market demand, (2) A recommended solution will depend on system operator preference and expert opinion, (3) The approach includes the deterministic N-1 criterion as a special case, (4) The regret measure may in some difficult cases lead to indecision between solutions. 84 refs., 71 figs., 2 tabs.

Flexible transfer limits in an open power market - Congestion versus risk of interruption

International Nuclear Information System (INIS)

Warland, Geir

1999-01-01

Traditionally, power systems have been operated by deterministic criteria which tend to provide conservative security limits and will be inflexible and insensitive to changes in outage probabilities or market demands in a deregulated power system. This thesis introduces a new approach to power system operation in which the determination of operating limits for critical transmission lines or corridors is presented as a multiobjective decision problem, including risk assessment. Two objectives are included: (1) minimization of operating cost and (2) obtaining a secure operating level. The operating costs included are congestion costs, interruption costs and the costs of corrective or preventive actions to enhance security. In modelling uncertainties, a fuzzy model for the amount of load lost due to outages is presented. It includes the subjective uncertainty in the assessment of the amount of load lost, considering weather dependency of outage probabilities. There are four main conclusions: (1) The approach is flexible and sensitive to changes in outage probabilities and market demand, (2) A recommended solution will depend on system operator preference and expert opinion, (3) The approach includes the deterministic N-1 criterion as a special case, (4) The regret measure may in some difficult cases lead to indecision between solutions. 84 refs., 71 figs., 2 tabs

Operation of Finnish nuclear power plants

International Nuclear Information System (INIS)

Tossavainen, K.

1990-12-01

During the second quarter of 1990 the Finnish nuclear plant units Loviisa 1 and 2 and TVO and II were in commercial operation for most of the time. The feedwater pipe rupture at Loviisa 1 and the resulting inspections and repairs at both Loviisa plant units brought about an outage the overall duration of which was 32 days. The annual maintenance outages of the TVO plant units were arranged during the report period and their combined duration was 31.5 days. Nuclear electricity accounted for 35.3% of the total Finnish electricity production during this quarter. The load factor average of the nuclear power plant units was 83.0%. Three events occurred during the report period which are classified as Level 1 on the International Nuclear Event Scale: feedwater pipe rupture at Loviisa 1, control rod withdrawal at TVO I in a test during an outage when the hydraulic scram system was rendered inoperable and erroneous fuel bundle transfers during control rod drives maintenance at TVO II. Other events during this quarter are classified as Level Zero (Below Scale) on the International Nuclear Event Scale. Occupational radiation doses and external releases of radioactivity were considerably below authorised limits. Only small amounts of nuclides originating in nuclear power plants were detected in samples taken in the vicinity of nuclear power plants

Efficient Simulation of the Outage Probability of Multihop Systems

KAUST Repository

Ben Issaid, Chaouki; Alouini, Mohamed-Slim; Tempone, Raul

2017-01-01

In this paper, we present an efficient importance sampling estimator for the evaluation of the outage probability of multihop systems with amplify-and-forward channel state-information-assisted. The proposed estimator is endowed with the bounded relative error property. Simulation results show a significant reduction in terms of number of simulation runs compared to naive Monte Carlo.

Efficient Simulation of the Outage Probability of Multihop Systems

KAUST Repository

Ben Issaid, Chaouki

2017-10-23

In this paper, we present an efficient importance sampling estimator for the evaluation of the outage probability of multihop systems with amplify-and-forward channel state-information-assisted. The proposed estimator is endowed with the bounded relative error property. Simulation results show a significant reduction in terms of number of simulation runs compared to naive Monte Carlo.

Real Mission Profile Based Lifetime Estimation of Fuel-cell Power Converter

DEFF Research Database (Denmark)

Zhou, Dao; Wang, Huai; Blaabjerg, Frede

2016-01-01

. This paper describes a lifetime prediction method for the power semiconductors used in the power conditioning of a fuel cell based backup system, considering both the long-term standby mode and active operation mode. The annual ambient temperature profile is taken into account to estimate its impact...... on the degradation of MOSFETs during the standby mode. At the presence of power outages, the backup system is activated into the operation mode and the MOSFETs withstand additional thermal stresses due to power losses. A study case of a 1 kW backup system is presented with two annual mission profiles in Denmark...... and India, respectively. The ambient temperature, occurrence frequency of power outages, active operation time and power levels are considered for the lifetime prediction of the applied MOSFETs. Comparisons of the accumulated lifetime consumptions are performed between standby mode and operation mode...

Outage performance analysis of underlay cognitive RF and FSO wireless channels

KAUST Repository

Ansari, Imran Shafique; Abdallah, Mohamed M.; Alouini, Mohamed-Slim; Qaraqe, Khalid A.

2014-01-01

In this work, the outage performance analysis of a dual-hop transmission system composed of asymmetric radio frequency (RF) channel cascaded with a free-space optical (FSO) link is presented. For the RF link, an underlay cognitive network

Investigation on cause of outage of Wide Range Monitor (WRM) in High Temperature engineering Test Reactor (HTTR). Transport operation toward investigation for cause of outage

International Nuclear Information System (INIS)

Shinohara, Masanori; Sawahata, Hiroaki; Kawamoto, Taiki; Saito, Kenji; Takada, Shoji; Yoshida, Naoaki; Isozaki, Ryosuke; Katsuyama, Kozo; Motegi, Toshihiro

2012-08-01

An event, in which one of WRMs were disabled to detect the neutron flux in the reactor core, occurred during the period of reactor shut down of HTTR in March, 2010. The actual life time of WRM was unexpectedly shorter than the past developed life time. Investigation of the cause of the outage of WRM toward the recovery of the life time up to the developed life is one of the issues to develop the technology basis of High Temperature Gas cooled Reactor (HTGR). Then, a post irradiation examination was planned to specify the damaged part causing the event in the WRM was also planned. For the investigation, the X-ray computed tomography scanner in Fuels Monitoring Facility (FMF). This report describes the preliminary investigation on the cause of outage of the WRM. The results of study for transportation method of the irradiated WRM from HTTR to FMF is also reported with the record to complete the transport operation. (author)

A RLS-SVM Aided Fusion Methodology for INS during GPS Outages.

Science.gov (United States)

Yao, Yiqing; Xu, Xiaosu

2017-02-24

In order to maintain a relatively high accuracy of navigation performance during global positioning system (GPS) outages, a novel robust least squares support vector machine (LS-SVM)-aided fusion methodology is explored to provide the pseudo-GPS position information for the inertial navigation system (INS). The relationship between the yaw, specific force, velocity, and the position increment is modeled. Rather than share the same weight in the traditional LS-SVM, the proposed algorithm allocates various weights for different data, which makes the system immune to the outliers. Field test data was collected to evaluate the proposed algorithm. The comparison results indicate that the proposed algorithm can effectively provide position corrections for standalone INS during the 300 s GPS outage, which outperforms the traditional LS-SVM method. Historical information is also involved to better represent the vehicle dynamics.

A RLS-SVM Aided Fusion Methodology for INS during GPS Outages

Directory of Open Access Journals (Sweden)

Yiqing Yao

2017-02-01

Full Text Available In order to maintain a relatively high accuracy of navigation performance during global positioning system (GPS outages, a novel robust least squares support vector machine (LS-SVM-aided fusion methodology is explored to provide the pseudo-GPS position information for the inertial navigation system (INS. The relationship between the yaw, specific force, velocity, and the position increment is modeled. Rather than share the same weight in the traditional LS-SVM, the proposed algorithm allocates various weights for different data, which makes the system immune to the outliers. Field test data was collected to evaluate the proposed algorithm. The comparison results indicate that the proposed algorithm can effectively provide position corrections for standalone INS during the 300 s GPS outage, which outperforms the traditional LS-SVM method. Historical information is also involved to better represent the vehicle dynamics.

Radio resource management scheme and outage analysis for network-assisted multi-hop D2D communications

Directory of Open Access Journals (Sweden)

Leila Melki

2016-11-01

Full Text Available In a cellular network it's very difficult to make spectrum resource more efficiently. Device-to-Device (D2D technology enables new service opportunities, and provides high throughput and reliable communication while reducing the base station load. For better total performance, short-range D2D links and cellular links share the same radio resource and the management of interference becomes a crucial task. Here we argue that single-hop D2D technology can be used to further improve cellular networks performance if the key D2D radio resource management algorithms are suitably extended to support multi-hop D2D communications. Aiming to establish a new paradigm for the analysis and design of multi-hop D2D communications, We propose a radio resource allocation for multi-hop D2D routes based on interference avoidance approach in LTE-A networks. On top of that, we investigate the outage probability of D2D communication. We first introduce a new definition of outage probability by considering the maximum distance to be allowable for single-hop transmission. Then we study and analyze the outage performance of a multi-hop D2D route. We derive the general closed form expression of outage probability of the multi-hop D2D routes. The results demonstrate that the D2D radio, sharing the same resources as the cellular network, provide higher capacity compared to pure cellular communication where all the data is transmitted through the base station. They also demonstrate that the new method of calculation of D2D multi hop outage probability has better performance than classical method defined in the literature.

Performance Analysis of Secrecy Outage Probability for AF-Based Partial Relay Selection with Outdated Channel Estimates

Directory of Open Access Journals (Sweden)

Kyu-Sung Hwang

2017-01-01

Full Text Available We study the secrecy outage probability of the amplify-and-forward (AF relaying protocol, which consists of one source, one destination, multiple relays, and multiple eavesdroppers. In this system, the aim is to transmit the confidential messages from a source to a destination via the selected relay in presence of eavesdroppers. Moreover, partial relay selection scheme is utilized for relay selection based on outdated channel state information where only neighboring channel information (source-relays is available and passive eavesdroppers are considered where a transmitter does not have any knowledge of eavesdroppers’ channels. Specifically, we offer the exact secrecy outage probability of the proposed system in a one-integral form as well as providing the asymptotic secrecy outage probability in a closed-form. Numerical examples are given to verify our provided analytical results for different system conditions.

Safety analysis program for steam generators replacement and power uprate at Tihange 2 nuclear power plant

International Nuclear Information System (INIS)

Delhaye, X.; Charlier, A.; Damas, Ph.; Druenne, H.; Mandy, C.; Parmentier, F.; Pirson, J.; Zhang, J.

2002-01-01

The Belgian Tihange 2 nuclear power plant went into commercial operation in 1983 producing a thermal power of 2785 MW. Since the commissioning of the plant the steam generators U-tubes have been affected by primary stress corrosion cracking. In order to avoid further degradation of the performance and an increase in repair costs, Electrabel, the owner of the plant, decided in 1997 to replace the 3 steam generators. This decision was supported by the feasibility study performed by Tractebel Energy Engineering which demonstrated that an increase of 10% of the initial power together with a fuel cycle length of 18 months was achieved. Tractebel Energy Engineering was entrusted by Electrabel as the owner's engineer to manage the project. This paper presents the role of Tractebel Energy Engineering in this project and the safety analysis program necessary to justify the new operation point and the fuel cycle extension to 18 months re-analysis of FSAR chapter 15 accidents and verification of the capacity of the safety and auxiliary systems. The FSAR chapter 15 accidents were reanalyzed jointly by Framatome and Tractebel Energy Engineering while the systems verifications were carried out by Tractebel Energy Engineering. (author)

The costs of power interruptions in Germany. An assessment in the light of the Energiewende

Energy Technology Data Exchange (ETDEWEB)

Growitsch, Christian; Malischek, Raimund; Nick, Sebastian; Wetzel, Heike

2013-04-15

The German Energiewende's potential effects on the reliability of electricity supply as well as the corresponding economic consequences have recently entered both the political and scientific debate. However, empirical evidence of power outage costs in Germany is rather scarce. Following a macroeconomic approach, we analyse the economic costs imposed by potential power interruptions in Germany. Investigating a rich data set on industry and households we estimate both Values of Lost Load (VoLLs) and associated costs of power interruptions for different German regions and sectors and every hour of the year. This disaggregated approach allows for conclusions for optimal load shedding in case of technical necessity and the economic efficiency of measures to improve security of supply. We find that interruption costs vary significantly over time, between sectors and regions. Peaking on midday of a Monday in December at 750 Mio Euro per hour, the average of total national outage costs amount to approximately 430 Mio Euro per hour. The industrial sectors facing the highest outage costs are the machinery and transport equipment sectors. Their aggregated hourly outage costs average out at approximately 20 Mio Euro. Our results emphasize the prominent regional aspect of the German Energiewende as the regions with the highest estimated cost of interruptions in South and West Germany coincide with the areas which face nuclear power plant shut downs in the near future.

OPG's approach of crediting natural circulation in outage heat sinks

International Nuclear Information System (INIS)

Fung, K.K.; Mackinnon, J.C.

2001-01-01

A review of crediting natural circulation as a backup means of removing the reactor core decay heat during an outage in Ontario Power Generation's nuclear stations was completed in 2000. The objective was to define the configurations and conditions under which natural circulation can be confidently credited as an effective heat transport mechanism for use in shutdown heat sink management. The project was an interdisciplinary program, and involved analyses in the areas of heat transport system thermalhydaulics, fuel and fuel channel thermal and mechanical behaviour, radiation physics, and probabilistic risks. The assessment shows that it is economically acceptable to credit natural circulation as a backup means of removing the core decay heat whenever the no fuel failure criteria are met. The economic risks associated with such a potential use decrease with time after shutdown. The waiting times after shutdown when there would be various levels of risks of damaging the pressure tubes and fuel bundles were derived for use in planning maintenance activities so as to minimize the economic risks. (author)

Nuclear power newsletter Vol. 2, no. 3

International Nuclear Information System (INIS)

2005-09-01

The topics presented in this newsletter are: factors contributing to increased nuclear electricity production for the period 1990-2004 ; NPP operating performance and life cycle management; improving human performance quality and technical infrastructure; and technology development and applications for advanced reactors. Three factors contributing the electricity production increase are analysed and presented - growth due to new power plants building (36%); existing NPP uprating (7%); and energy availability improvements (57%). Trends of installed capacity and available production are given. The newsletter also presents technical issues that influence decisions on operation and nuclear power infrastructure and delayed NPPs. In the last article technology advances are presented in details for water cooled reactors, fast reactors and accelerator driven systems, gas cooled reactors and desalination plants

Pressure and temperature analyses using GOTHIC for Mark I containment of the Chinshan Nuclear Power Plant

Energy Technology Data Exchange (ETDEWEB)

Chen, Yen-Shu, E-mail: yschen@iner.org.t [Nuclear Engineering Division, Institute of Nuclear Energy Research, 1000, Wenhua Rd., Jiaan Village, Longtan Township, Taoyuan County 32546, Taiwan (China); Yuann, Yng-Ruey; Dai, Liang-Che; Lin, Yon-Pon [Nuclear Engineering Division, Institute of Nuclear Energy Research, 1000, Wenhua Rd., Jiaan Village, Longtan Township, Taoyuan County 32546, Taiwan (China)

2011-05-15

Research highlights: The Chinshan Mark I containment pressure-temperature responses are analyzed. GOTHIC is used to calculate the containment responses under three pipe break events. This study is used to support the Chinshan Stretch Power Uprate (SPU) program. The calculated peak pressure and temperature are still below the design values. The Chinshan containment integrity can be maintained under SPU condition. - Abstract: Chinshan Nuclear Power Plant in Taiwan is a GE-designed twin-unit BWR/4 plant with original licensed thermal power (OLTP) of 1775 MWt for each unit. Recently, the Stretch Power Uprate (SPU) program for the Chinshan plant is being conducted to uprate the core thermal power to 1858 MWt (104.66% OLTP). In this study, the Chinshan Mark I containment pressure/temperature responses during LOCA at 105% OLTP (104.66% OLTP + 0.34% OLTP power uncertainty = 105% OLTP) are analyzed using the containment thermal-hydraulic program GOTHIC. Three kinds of LOCA (Loss of Coolant Accident) scenarios are investigated: Recirculation Line Break (RCLB), Main Steam Line Break (MSLB), and Feedwater Line Break (FWLB). In the short-term analyses, blowdown data generated by RELAP5 transient analyses are provided as boundary conditions to the GOTHIC containment model. The calculated peak drywell pressure and temperature in the RCLB event are 217.2 kPaG and 137.1 {sup o}C, respectively, which are close to the original FSAR results (219.2 kPaG and 138.4 {sup o}C). Additionally, the peak drywell temperature of 155.3 {sup o}C calculated by MSLB is presented in this study. To obtain the peak suppression pool temperature, a long-term RCLB analysis is performed using a simplified RPV (Reactor Pressure Vessel) volume to calculate blowdown flow rate. One RHR (Residual Heat Removal) heat exchanger is assumed to be inoperable for suppression pool cooling mode. The calculated peak suppression pool temperature is 93.2 {sup o}C, which is below the pool temperature used for evaluating the

Pressure and temperature analyses using GOTHIC for Mark I containment of the Chinshan Nuclear Power Plant

International Nuclear Information System (INIS)

Chen, Yen-Shu; Yuann, Yng-Ruey; Dai, Liang-Che; Lin, Yon-Pon

2011-01-01

Research highlights: → The Chinshan Mark I containment pressure-temperature responses are analyzed. → GOTHIC is used to calculate the containment responses under three pipe break events. → This study is used to support the Chinshan Stretch Power Uprate (SPU) program. → The calculated peak pressure and temperature are still below the design values. → The Chinshan containment integrity can be maintained under SPU condition. - Abstract: Chinshan Nuclear Power Plant in Taiwan is a GE-designed twin-unit BWR/4 plant with original licensed thermal power (OLTP) of 1775 MWt for each unit. Recently, the Stretch Power Uprate (SPU) program for the Chinshan plant is being conducted to uprate the core thermal power to 1858 MWt (104.66% OLTP). In this study, the Chinshan Mark I containment pressure/temperature responses during LOCA at 105% OLTP (104.66% OLTP + 0.34% OLTP power uncertainty = 105% OLTP) are analyzed using the containment thermal-hydraulic program GOTHIC. Three kinds of LOCA (Loss of Coolant Accident) scenarios are investigated: Recirculation Line Break (RCLB), Main Steam Line Break (MSLB), and Feedwater Line Break (FWLB). In the short-term analyses, blowdown data generated by RELAP5 transient analyses are provided as boundary conditions to the GOTHIC containment model. The calculated peak drywell pressure and temperature in the RCLB event are 217.2 kPaG and 137.1 o C, respectively, which are close to the original FSAR results (219.2 kPaG and 138.4 o C). Additionally, the peak drywell temperature of 155.3 o C calculated by MSLB is presented in this study. To obtain the peak suppression pool temperature, a long-term RCLB analysis is performed using a simplified RPV (Reactor Pressure Vessel) volume to calculate blowdown flow rate. One RHR (Residual Heat Removal) heat exchanger is assumed to be inoperable for suppression pool cooling mode. The calculated peak suppression pool temperature is 93.2 o C, which is below the pool temperature used for evaluating the

Risk contribution from low power, shutdown, and other operational modes beyond full power

Energy Technology Data Exchange (ETDEWEB)

Whitehead, D.W.; Brown, T.D. [Sandia National Labs., Albuquerque, NM (United States); Chu, T.L. [Brookhaven National Lab., Upton, NY (United States)] [and others

1995-04-01

During 1989 the Nuclear Regulatory Commission (NRC) initiated an extensive program to carefully examine the potential risks during low power and shutdown operations. Two plants, Surry (a pressurized water reactor) and Grand Gulf (a boiling water reactor), were selected for study by Brookhaven National Laboratory and Sandia National Laboratories, respectively. The program objectives included assessing the risks of severe accidents initiated during plant operational states other than full power and comparing estimated core damage frequencies, important accident sequences, and other qualitative and quantitative results with full power accidents as assessed in NUREG-1150. The scope included a Level 3 probabilistic risk assessment (PRA) for traditional internal events and a Level 1 PRA on fire, flooding, and seismically induced core damage sequences. A phased approach was used in Level 1. In Phase 1 the concept of plant operational states (POSs) was developed to provide a better representation of the plant as it transitions from power to nonpower operation. This included a coarse screening analysis of all POSs to identify vulnerable plant configurations, to characterize (on a high, medium, or low basis) potential frequencies of core damage accidents, and to provide a foundation for a detailed Phase 2 analysis. In Phase 2, selected POSs from both Grand Gulf and Surry were chosen for detailed analysis. For Grand Gulf, POS 5 (approximately cold shutdown as defined by Grand Gulf Technical Specifications) during a refueling outage was selected. For Surry, three POSs representing the time the plant spends in midloop operation were chosen for analysis. These included POS 6 and POS 10 of a refueling outage and POS 6 of a drained maintenance outage. Level 1 and Level 2/3 results from both the Surry and Grand Gulf analyses are presented.

Risk contribution from low power, shutdown, and other operational modes beyond full power

International Nuclear Information System (INIS)

Whitehead, D.W.; Brown, T.D.; Chu, T.L.; Pratt, W.T.

1995-01-01

During 1989 the Nuclear Regulatory Commission (NRC) initiated an extensive program to carefully examine the potential risks during low power and shutdown operations. Two plants, Surry (a pressurized water reactor) and Grand Gulf (a boiling water reactor), were selected for study by Brookhaven National Laboratory and Sandia National Laboratories, respectively. The program objectives included assessing the risks of severe accidents initiated during plant operational states other than full power and comparing estimated core damage frequencies, important accident sequences, and other qualitative and quantitative results with full power accidents as assessed in NUREG-1150. The scope included a Level 3 probabilistic risk assessment (PRA) for traditional internal events and a Level 1 PRA on fire, flooding, and seismically induced core damage sequences. A phased approach was used in Level 1. In Phase 1 the concept of plant operational states (POSs) was developed to provide a better representation of the plant as it transitions from power to nonpower operation. This included a coarse screening analysis of all POSs to identify vulnerable plant configurations, to characterize (on a high, medium, or low basis) potential frequencies of core damage accidents, and to provide a foundation for a detailed Phase 2 analysis. In Phase 2, selected POSs from both Grand Gulf and Surry were chosen for detailed analysis. For Grand Gulf, POS 5 (approximately cold shutdown as defined by Grand Gulf Technical Specifications) during a refueling outage was selected. For Surry, three POSs representing the time the plant spends in midloop operation were chosen for analysis. These included POS 6 and POS 10 of a refueling outage and POS 6 of a drained maintenance outage. Level 1 and Level 2/3 results from both the Surry and Grand Gulf analyses are presented

Energy Non-Availability in Distribution Grids with Heavy Penetration of Solar Power: Assessment and Mitigation through Solar Smoother

Directory of Open Access Journals (Sweden)

Tathagata Sarkar

2018-03-01

Full Text Available Rapid fluctuation of solar irradiance due to cloud passage causes corresponding variations in the power output of solar PV power plants. This leads to rapid voltage instability at the point of common coupling (PCC of the connected grid which may cause temporary shutdown of the plant leading to non-availability of energy in the connected load and distribution grid. An estimate of the duration and frequency of this outage is important for solar energy generators to ensure the generation and performance of the solar power plant. A methodology using PVsyst (6.6.4, University of Geneva, Geneva, Switzerland and PSCAD (4.5, Manitoba HVDC Research Centre, Winnipeg, MB, Canada simulation has been developed to estimate the duration and frequency of power outages due to rapid fluctuation of solar irradiance throughout the year. It is shown that the outage depends not only on the solar irradiance fluctuation, but also on the grid parameters of the connected distribution grid. A practical case study has been done on a 500 kilo Watt peak (kWp solar PV power plant for validation of the proposed methodology. It is observed that the energy non-availability for this plant is about 13% per year. This can be reduced to 8% by incorporating a solar smoother. A financial analysis of this outage and its mitigation has also been carried out.

Safety and Radiation Protection at Swedish Nuclear Power Plants 2005

International Nuclear Information System (INIS)

2006-05-01

carried out. Forsmarks Kraftgrupp AB (FKA) has applied for permission for power uprates at the Forsmark 1-3 reactors, OKG has applied for permission for power uprates at the Oskarshamn 3 reactor and RAB has applied for permission for power uprates at the Ringhals 1 and 3 reactors. SKI has reviewed the applications from OKG and RAB and has found that the necessary conditions exist for implementing the power uprates that have been requested. The Government has decided to grant permission for power uprates at Ringhals 1 and 3. SKI's regulations (SKIFS 2004:2) concerning the design and construction of nuclear reactors entered into force with certain transitional regulations on January 1, 2005. Through these regulations, SKI has developed and clarified the safety requirements for nuclear reactors. The transitional agreements mean that the licensees concerned must be given the necessary time to plan and implement the measures at the reactors that are necessary in order to comply with the regulations. The regulations mean that extensive measures need to be conducted at the reactors, especially the older reactors, in order to further improve safety to the modern level that the requirements entail. The safety improvement work will be conducted for a relatively long period of time. During the same period, power uprates are being planned at several reactors. During the year, SKI also decided on new regulations (SKIFS 2005:1) for the physical protection of nuclear facilities. These regulations will also have extensive consequences for the licensees, through more stringent regulations with respect to area protection, perimeter protection and access control. During the year, SKI continued to follow up and promote the further development of the licensees' internal audit functions, management systems and competence assurance processes. SKI notes that continued improvements have been implemented and that the independent audit functions have been reinforced among other things. Up

Safety and Radiation Protection at Swedish Nuclear Power Plants 2005

Energy Technology Data Exchange (ETDEWEB)

NONE

2006-05-15

need to be carried out. Forsmarks Kraftgrupp AB (FKA) has applied for permission for power uprates at the Forsmark 1-3 reactors, OKG has applied for permission for power uprates at the Oskarshamn 3 reactor and RAB has applied for permission for power uprates at the Ringhals 1 and 3 reactors. SKI has reviewed the applications from OKG and RAB and has found that the necessary conditions exist for implementing the power uprates that have been requested. The Government has decided to grant permission for power uprates at Ringhals 1 and 3. SKI's regulations (SKIFS 2004:2) concerning the design and construction of nuclear reactors entered into force with certain transitional regulations on January 1, 2005. Through these regulations, SKI has developed and clarified the safety requirements for nuclear reactors. The transitional agreements mean that the licensees concerned must be given the necessary time to plan and implement the measures at the reactors that are necessary in order to comply with the regulations. The regulations mean that extensive measures need to be conducted at the reactors, especially the older reactors, in order to further improve safety to the modern level that the requirements entail. The safety improvement work will be conducted for a relatively long period of time. During the same period, power uprates are being planned at several reactors. During the year, SKI also decided on new regulations (SKIFS 2005:1) for the physical protection of nuclear facilities. These regulations will also have extensive consequences for the licensees, through more stringent regulations with respect to area protection, perimeter protection and access control. During the year, SKI continued to follow up and promote the further development of the licensees' internal audit functions, management systems and competence assurance processes. SKI notes that continued improvements have been implemented and that the independent audit functions have been reinforced among

Light Water Reactor Sustainability Program: Analysis of Pressurized Water Reactor Station Blackout caused by external flooding using the RISMC toolkit

International Nuclear Information System (INIS)

2014-01-01

The existing fleet of nuclear power plants is in the process of extending its lifetime and increasing the power generated from these plants via power uprates. In order to evaluate the impacts of these two factors on the safety of the plant, the Risk Informed Safety Margin Characterization project aims to provide insights to decision makers through a series of simulations of the plant dynamics for different initial conditions (e.g., probabilistic analysis and uncertainty quantification). This paper focuses on the impacts of power uprate on the safety margin of a boiling water reactor for a flooding induced station black-out event. Analysis is performed by using a combination of thermal-hydraulic codes and a stochastic analysis tool currently under development at the Idaho National Laboratory, i.e. RAVEN. We employed both classical statistical tools, i.e. Monte-Carlo, and more advanced machine learning based algorithms to perform uncertainty quantification in order to quantify changes in system performance and limitations as a consequence of power uprate. Results obtained give a detailed investigation of the issues associated with a plant power uprate including the effects of station black-out accident scenarios. We were able to quantify how the timing of specific events was impacted by a higher nominal reactor core power. Such safety insights can provide useful information to the decision makers to perform risk informed margins management.

Modernization of electric power systems of the Laguna Verde Nuclear Power Plant; Modernizacion de los sistemas electricos de potencia de la Central Nuclear de Laguna Verde

Energy Technology Data Exchange (ETDEWEB)

Gabaldon, M. A.; Gonzalez, J. J.; Prieto, I.

2011-07-01

The Power Increase Project of Laguna Verde Nuclear Plant has entailed the replacement, in one unique outage, of the main power electrical systems of the Plant (Isolated Phase Bars, Generator Circuit Breaker and Main Transformer) as well as the replacement of the Turbo-group. The simultaneous substitution of these entire system has never been done by any other Plant in the world, representing an engineering challenge that embraced the design of the new equipment up to the planning, coordination and management of the construction and commissioning works, which were successfully carried out by Iberdrola within the established outage period /47 days) for both units. (Author)

Outage analysis for underlay cognitive networks using incremental regenerative relaying

KAUST Repository

Tourki, Kamel

2013-02-01

Cooperative relay technology has recently been introduced into cognitive radio (CR) networks to enhance the network capacity, scalability, and reliability of end-to-end communication. In this paper, we investigate an underlay cognitive network where the quality of service (QoS) of the secondary link is maintained by triggering an opportunistic regenerative relaying once it falls under an unacceptable level. Analysis is conducted for two schemes, referred to as the channel-state information (CSI)-based and fault-tolerant schemes, respectively, where different amounts of CSI were considered. We first provide the exact cumulative distribution function (cdf) of the received signal-to-noise ratio (SNR) over each hop with colocated relays. Then, the cdf\\'s are used to determine a very accurate closed-form expression for the outage probability for a transmission rate $R$. In a high-SNR region, a floor of the secondary outage probability occurs, and we derive its corresponding expression. We validate our analysis by showing that the simulation results coincide with our analytical results in Rayleigh fading channels. © 1967-2012 IEEE.

Analysis of power loss data for the 200 Area Tank Farms in support of K Basin SAR work

International Nuclear Information System (INIS)

Shultz, M.V. Jr.

1994-12-01

An analysis of power loss data for the 200 Area Tank Farms was performed in support of K Basin safety analysis report work. The purpose of the analysis was to establish a relationship between the length of a power outage and its yearly frequency. This relationship can be used to determine whether the duration of a specific power loss is a risk concern. The information was developed from data contained in unusual occurrence reports (UORs) spanning a continuous period of 19.75 years. The average frequency of power loss calculated from the UOR information is 1.22 events per year. The mean of the power loss duration is 32.5 minutes an the median duration is 2 minutes. Nine events resulted in loss of power to both 200 East and 200 West areas simultaneously. Seven events (not necessarily the same events that resulted in loss of power to both 200 areas) resulted in outage durations exceeding 5 minutes. Approximately one-half of the events were caused by human error. The other half resulted from natural phenomena or equipment failures. None of the outages were reported to have any adverse effect on the tank farms

Outage Analysis of Practical FSO/RF Hybrid System With Adaptive Combining

KAUST Repository

Rakia, Tamer

2015-08-01

Hybrid free-space optical (FSO)/radio-frequency (RF) systems have emerged as a promising solution for high-data-rate wireless transmission. We present and analyze a transmission scheme for the hybrid FSO/RF communication system based on adaptive combining. Specifically, only FSO link is active as long as the instantaneous signal-to-noise ratio (SNR) at the FSO receiver is above a certain threshold level. When it falls below this threshold level, the RF link is activated along with the FSO link and the signals from the two links are combined at the receiver using a dual-branch maximal ratio combiner. Novel analytical expression for the cumulative distribution function (CDF) of the received SNR for the proposed hybrid system is obtained. This CDF expression is used to study the system outage performance. Numerical examples are presented to compare the outage performance of the proposed hybrid FSO/RF system with that of the FSO-only and RF-only systems. © 1997-2012 IEEE.

Zero-Outage Cellular Downlink with Fixed-Rate D2D Underlay

DEFF Research Database (Denmark)

Kiilerich Pratas, Nuno; Popovski, Petar

2015-01-01

. D2D connections can be instrumental in localized aggregation of uplink M2M traffic to a more capable cellular device, before being finally delivered to the Base Station (BS). In this paper we show that a fixed M2M rate is an enabler of efficient Machine-Type D2D underlay operation taking place......, but not the interfering channels from the MTDs to U, we prove that there is a positive downlink rate that can always be decoded by U, leading to zero-outage of the downlink signal. This is a rather surprising consequence of the features of the multiple access channel and the fixed rate RM. We also consider the case...... of a simpler, single-user decoder at U with successive interference cancellation. However, with single-user decoder, a positive zero-outage rate exists only when NM = 1 and is zero when NM > 1. This implies that joint decoding is instrumental in enabling fixed-rate underlay operation....

Availability Improvement of German Nuclear Power Plants

International Nuclear Information System (INIS)

Wilhelm, Oliver

2008-01-01

High availability is important for the safety and economical performance of Nuclear Power Plants (NPP). The strategy for availability improvement in a typical German PWR shall be discussed here. Key parameters for strategy development are plant design, availability of safety systems, component reliability, preventive maintenance and outage organization. Plant design, availability of safety systems and component reliability are to a greater extent given parameters that can hardly be influenced after the construction of the plant. But they set the frame for maintenance and outage organisation which have shown to have a large influence on the availability of the plant. (author)

power system reliability in supplying nuclear reactors

International Nuclear Information System (INIS)

Gad, M.M.M.

2007-01-01

this thesis presents a simple technique for deducing minimal cut set (MCS) from the defined minimal path set (MPS) of generic distribution system and this technique have been used to evaluate the basic reliability indices of Egypt's second research reactor (ETRR-2) electrical distribution network. the alternative system configurations are then studied to evaluate their impact on service reliability. the proposed MCS approach considers both sustained and temporary outage. the temporary outage constitutes an important parameter in characterizing the system reliability indices for critical load point in distribution system. it is also consider the power quality impact on the reliability indices

Simulations of the design basis accident at conditions of power increase and the o transient of MSIV at overpressure conditions of the Laguna Verde Power Station; Simulaciones del accidente base de diseno a condiciones de aumento de potencia y del transitorio de cierre de MSIV a condiciones de sobrepresion de la Central Laguna Verde

Energy Technology Data Exchange (ETDEWEB)

Araiza M, E.; Nunez C, A. [Comision Nacional de Seguridad Nuclear y Salvaguardias, 03000 Mexico D.F. (Mexico)

2001-07-01

This document presents the analysis of the simulation of the loss of coolant accident at uprate power conditions, that is 2027 MWt (105% of the current rated power of 1931MWt). This power was reached allowing an increase in the turbine steam flow rate without changing the steam dome pressure value at its rated conditions (1020 psiaJ. There are also presented the results of the simulation of the main steam isolation va/ve transient at overpressure conditions 1065 psia and 1067 MWt), for Laguna Verde Nuclear Power Station. Both simulations were performed with the best estimate computer code TRA C BF1. The results obtained in the loss of coolant accident show that the emergency core coolant systems can recover the water level in the core before fuel temperature increases excessively, and that the peak pressure reached in the drywell is always below its design pressure. Therefore it is concluded that the integrity of the containment is not challenged during a loss of coolant accident at uprate power conditions.The analysis of the main steam isolation valve transients at overpressure conditions, and the analysis of the particular cases of the failure of one to six safety relief valves to open, show that the vessel peak pressures are below the design pressure and have no significant effect on vessel integrity. (Author)

Outage probability analysis of wireless sensor networks in the presence of channel fading and spatial correlation

KAUST Repository

Al-Murad, Tamim M.

2011-07-01

Evaluating the reliability of wireless sensor networks is becoming more important as theses networks are being used in crucial applications. The outage probability defined as the probability that the error in the system exceeds a maximum acceptable threshold has recently been used as a measure of the reliability of such systems. In this work we find the outage probability of wireless sensor network in different scenarios of distributed sensing where sensors\\' readings are affected by spatial correlation and in the presence of channel fading. © 2011 IEEE.

Operation of Finnish nuclear power plants

International Nuclear Information System (INIS)

Tossavainen, K.

1994-03-01

In the third quarter of 1993, all of Finland's four nuclear power plant units were in power operation, with the exception of the annual maintenance outages of the Loviisa units. The load factor average of the plant units was 83.6 %. None of the events which occurred during this annual quarter had any bearing on nuclear or radiation safety. (4 figs., 5 tabs.)

Two-Way Multiuser Mixed RF/FSO Relaying: Performance Analysis and Power Allocation

KAUST Repository

Al-Eryani, Yasser F.

2018-03-21

In this paper, the performance of two-way multiuser mixed radio frequency/free space optical (RF/FSO) relay networks with opportunistic user scheduling and asymmetric channel fading is studied. RF links are used to conduct data transmission between users and relay node, while a FSO link is used to conduct data transmission on the last-mile communication link between the relay node and base station. The RF links are assumed to follow a Rayleigh fading model, while the FSO links are assumed to follow a unified Gamma-Gamma atmospheric turbulence fading model with pointing error. First, closed-form expressions for the exact outage probability, asymptotic (high signal-to-noise ratio) outage probability, average symbol error rate, and average ergodic channel capacity are derived assuming a heterodyne detection scheme. The asymptotic results are used to conduct a power optimization algorithm where expressions for optimal transmission power values for the transmitting nodes are provided. Additionally, performance comparisons between the considered two-way-relaying (TWR) network and the oneway- relaying (OWR) network are provided and discussed. Also, the impact of several system parameters, including number of users, pointing errors, atmospheric turbulence conditions, and outage probability threshold on the overall network performance are investigated. All the theoretical results are validated by Monte Carlo simulations. The results show that the TWR scheme almost doubles the network ergodic capacity compared to that of the OWR scheme with the same outage performance. Additionally, it is shown that under weak-to-moderate weather turbulence conditions and small pointing error, the outage probability is dominated by the RF downlink with a neglected effect for the user selection process at the RF uplink transmission. However, for severe pointing error, the outage probability is dominated by the FSO uplink/downlink transmission.

Justification for an Increase in Authorized Operating Power at HFIR

International Nuclear Information System (INIS)

Primm, Trent; Ilas, Germina

2011-01-01

Using verified and validated reactor physics methods coupled to a currently accepted thermal hydraulic analysis methodology, onset of incipient boiling power agrees well with the currently-accepted safety basis value. The MCNP-based methodology is acceptable for scoping studies of LEU fuel conversion. A balance-of-plant assessment would have to be conducted to determine if the power up-rate to 100 MW could be supported for LEU fuel. While analyses performed 45 years ago have been shown to be in agreement with today s methods, there is an advantage to the current methodology in that people working at HFIR today can explain/justify/defend the safety analyses rather than relying solely on documentation.

Index-based reactive power compensation scheme for voltage regulation

Science.gov (United States)

Dike, Damian Obioma

2008-10-01

Increasing demand for electrical power arising from deregulation and the restrictions posed to the construction of new transmission lines by environment, socioeconomic, and political issues had led to higher grid loading. Consequently, voltage instability has become a major concern, and reactive power support is vital to enhance transmission grid performance. Improved reactive power support to distressed grid is possible through the application of relatively unfamiliar emerging technologies of "Flexible AC Transmission Systems (FACTS)" devices and "Distributed Energy Resources (DERS)." In addition to these infrastructure issues, a lack of situational awareness by system operators can cause major power outages as evidenced by the August 14, 2003 widespread North American blackout. This and many other recent major outages have highlighted the inadequacies of existing power system indexes. In this work, a novel "Index-based reactive compensation scheme" appropriate for both on-line and off-line computation of grid status has been developed. A new voltage stability index (Ls-index) suitable for long transmission lines was developed, simulated, and compared to the existing two-machine modeled L-index. This showed the effect of long distance power wheeling amongst regional transmission organizations. The dissertation further provided models for index modulated voltage source converters (VSC) and index-based load flow analysis of both FACTS and microgrid interconnected power systems using the Newton-Raphson's load flow model incorporated with multi-FACTS devices. The developed package has been made user-friendly through the embodiment of interactive graphical user interface and implemented on the IEEE 14, 30, and 300 bus systems. The results showed reactive compensation has system wide-effect, provided readily accessible system status indicators, ensured seamless DERs interconnection through new islanding modes and enhanced VSC utilization. These outcomes may contribute

Energy Efficiency Maximization for WSNs with Simultaneous Wireless Information and Power Transfer.

Science.gov (United States)

Yu, Hongyan; Zhang, Yongqiang; Guo, Songtao; Yang, Yuanyuan; Ji, Luyue

2017-08-18

Recently, the simultaneous wireless information and power transfer (SWIPT) technique has been regarded as a promising approach to enhance performance of wireless sensor networks with limited energy supply. However, from a green communication perspective, energy efficiency optimization for SWIPT system design has not been investigated in Wireless Rechargeable Sensor Networks (WRSNs). In this paper, we consider the tradeoffs between energy efficiency and three factors including spectral efficiency, the transmit power and outage target rate for two different modes, i.e., power splitting (PS) and time switching modes (TS), at the receiver. Moreover, we formulate the energy efficiency maximization problem subject to the constraints of minimum Quality of Service (QoS), minimum harvested energy and maximum transmission power as non-convex optimization problem. In particular, we focus on optimizing power control and power allocation policy in PS and TS modes to maximize energy efficiency of data transmission. For PS and TS modes, we propose the corresponding algorithm to characterize a non-convex optimization problem that takes into account the circuit power consumption and the harvested energy. By exploiting nonlinear fractional programming and Lagrangian dual decomposition, we propose suboptimal iterative algorithms to obtain the solutions of non-convex optimization problems. Furthermore, we derive the outage probability and effective throughput from the scenarios that the transmitter does not or partially know the channel state information (CSI) of the receiver. Simulation results illustrate that the proposed optimal iterative algorithm can achieve optimal solutions within a small number of iterations and various tradeoffs between energy efficiency and spectral efficiency, transmit power and outage target rate, respectively.

Energy Efficiency Maximization for WSNs with Simultaneous Wireless Information and Power Transfer

Science.gov (United States)

Yu, Hongyan; Zhang, Yongqiang; Yang, Yuanyuan; Ji, Luyue

2017-01-01

Recently, the simultaneous wireless information and power transfer (SWIPT) technique has been regarded as a promising approach to enhance performance of wireless sensor networks with limited energy supply. However, from a green communication perspective, energy efficiency optimization for SWIPT system design has not been investigated in Wireless Rechargeable Sensor Networks (WRSNs). In this paper, we consider the tradeoffs between energy efficiency and three factors including spectral efficiency, the transmit power and outage target rate for two different modes, i.e., power splitting (PS) and time switching modes (TS), at the receiver. Moreover, we formulate the energy efficiency maximization problem subject to the constraints of minimum Quality of Service (QoS), minimum harvested energy and maximum transmission power as non-convex optimization problem. In particular, we focus on optimizing power control and power allocation policy in PS and TS modes to maximize energy efficiency of data transmission. For PS and TS modes, we propose the corresponding algorithm to characterize a non-convex optimization problem that takes into account the circuit power consumption and the harvested energy. By exploiting nonlinear fractional programming and Lagrangian dual decomposition, we propose suboptimal iterative algorithms to obtain the solutions of non-convex optimization problems. Furthermore, we derive the outage probability and effective throughput from the scenarios that the transmitter does not or partially know the channel state information (CSI) of the receiver. Simulation results illustrate that the proposed optimal iterative algorithm can achieve optimal solutions within a small number of iterations and various tradeoffs between energy efficiency and spectral efficiency, transmit power and outage target rate, respectively. PMID:28820496

Secrecy Outage of Max-Min TAS Scheme in MIMO-NOMA Systems

KAUST Repository

Lei, Hongjiang

2018-04-09

This paper considers a secure non-orthogonal multiple access system, where confidential messages are transmitted from a base station to multiple legitimate destinations and wiretapped by multiple illegitimate receivers. It is assumed that all the channels experience Nakagami-m fading model and all the nodes are equipped with multiple antennas, respectively. Both non-colluding and colluding eavesdroppers are respectively considered. Max-min (MM) transmit antenna selection (TAS) strategy is adopted to improve the secrecy performance of the target system, in which both users in user paring are considered simultaneously. In particular, closed-form expressions for the cumulative distribution function of the signal-to-interference-noise ratio at the legitimate user are derived firstly. Then we obtain the exact and asymptotic analytical results in a closed form for the secrecy outage probability of MM TAS scheme. Monte-Carlo simulation results are presented to corroborate the correctness of the analysis. The results show that the secrecy diversity order is zero and non-zero for fixed and dynamic power allocations, respectively.

Secrecy Outage of Max-Min TAS Scheme in MIMO-NOMA Systems

KAUST Repository

Lei, Hongjiang; Zhang, Jianming; Park, Kihong; Xu, Peng; Zhang, Zufan; Pan, Gaofeng; Alouini, Mohamed-Slim

2018-01-01

This paper considers a secure non-orthogonal multiple access system, where confidential messages are transmitted from a base station to multiple legitimate destinations and wiretapped by multiple illegitimate receivers. It is assumed that all the channels experience Nakagami-m fading model and all the nodes are equipped with multiple antennas, respectively. Both non-colluding and colluding eavesdroppers are respectively considered. Max-min (MM) transmit antenna selection (TAS) strategy is adopted to improve the secrecy performance of the target system, in which both users in user paring are considered simultaneously. In particular, closed-form expressions for the cumulative distribution function of the signal-to-interference-noise ratio at the legitimate user are derived firstly. Then we obtain the exact and asymptotic analytical results in a closed form for the secrecy outage probability of MM TAS scheme. Monte-Carlo simulation results are presented to corroborate the correctness of the analysis. The results show that the secrecy diversity order is zero and non-zero for fixed and dynamic power allocations, respectively.

Economic and Environmental Impacts of the Columbia-Snake River Extended Lock Outage

Science.gov (United States)

2012-03-01

This reports main objective is to analyze the change in rates and modal costs for shippers, commodity industries and ports prior to, during and after the fifteen week lock outage and to determine the impacts on the environment in the form of energ...

Providing Limited Local Electric Service During a Major Grid Outage: A First Assessment Based on Customer Willingness to Pay.

Science.gov (United States)

Baik, Sunhee; Morgan, M Granger; Davis, Alexander L

2018-02-01

While they are rare, widespread blackouts of the bulk power system can result in large costs to individuals and society. If local distribution circuits remain intact, it is possible to use new technologies including smart meters, intelligent switches that can change the topology of distribution circuits, and distributed generation owned by customers and the power company, to provide limited local electric power service. Many utilities are already making investments that would make this possible. We use customers' measured willingness to pay to explore when the incremental investments needed to implement these capabilities would be justified. Under many circumstances, upgrades in advanced distribution systems could be justified for a customer charge of less than a dollar a month (plus the cost of electricity used during outages), and would be less expensive and safer than the proliferation of small portable backup generators. We also discuss issues of social equity, extreme events, and various sources of underlying uncertainty. © 2017 Society for Risk Analysis.

Outage Analysis of Train-to-Train Communication Model over Nakagami-m Channel in High-Speed Railway

Directory of Open Access Journals (Sweden)

Pengyu Liu

2013-01-01

Full Text Available This paper analyzes the end-to-end outage performance of high-speed-railway train-to-train communication model in high-speed railway over independent identical and nonidentical Nakagami-m channels. The train-to-train communication is inter-train communication without an aid of infrastructure (for base station. Source train uses trains on other rail tracks as relays to transmit signals to destination train on the same track. The mechanism of such communication among trains can be divided into three cases based on occurrence of possible-occurrence relay trains. We first present a new closed form for the sum of squared independent Nakagami-m variates and then derive an expression for the outage probability of the identical and non-identical Nakagami-m channels in three cases. In particular, the problem is improved by the proposed formulation that statistic for sum of squared Nakagami-m variates with identical m tends to be infinite. Numerical analysis indicates that the derived analytic results are reasonable and the outage performance is better over Nakagami-m channel in high-speed railway scenarios.

Economic Viability Improvement of Solar Powered Indian Rural Banks through DC Grids

NARCIS (Netherlands)

Panguloori, R.

2012-01-01

Power shortages result in power outages for period of 8 to 10 Hrs aday in rural areas due to significant gap between electricity demandand supply. Rural banking is one of the sectors severely affected by power. Majority of population in emerging markets like India livein rural areas. Therefore,

Use of ABB ADVANT Power for large scale instrumentation and controls replacements in nuclear power plants

International Nuclear Information System (INIS)

Pucak, J.L.; Brown, E.M.

1999-01-01

One of the major issues facing plants planning for life extension is the viability and feasibility of modernization of a plant's existing I and C systems including the safety systems and the control room. This paper discusses the ABB approach to the implementation of large scale Instrumentation and Controls (I and C) modernization. ABB applies a segmented architecture approach using the ADVANT Power control system to meet the numerous constraints of a major I and C upgrade program. The segmented architecture and how it supports implementation of a complete I and C upgrade either in one outage or in a series of outages is presented. ADVANT Power contains standardized industrial control equipment that is designed to support 1E applications as well as turbine and non-1E process control. This equipment forms the basis for the architecture proposed for future new nuclear plant sales as well as large scale retrofits. (author)

Determination of the sources of the airborne physico-chemical 131I species in a PWR power plant

International Nuclear Information System (INIS)

Deuber, H.; Wilhelm, J.G.

1978-01-01

In a 1300 MWE PWR power plant the sources of the airborne 131 I species were determined over a period of 5 months. During power operation the main source of the radiologically decisive elemental 131 I was the exhaust from the hoods in which samples from the primary coolant are taken and processed. During refueling outage elemental 131 I was mainly contributed by the containment purge air. By efficient filtration of these exhausts, a reduction of the ingestion dose, caused by the total 131 I stack release, by a factor of nearly 4 during power operation and of possibly 10 during refueling outage can be accomplished. (author)

A Unified Moment-Based Approach for the Evaluation of the Outage Probability with Noise and Interference