BWR shutdown analyzer using artificial intelligence (AI) techniques

International Nuclear Information System (INIS)

Cain, D.G.

1986-01-01

A prototype alarm system for detecting abnormal reactor shutdowns based on artificial intelligence technology is described. The system incorporates knowledge about Boiling Water Reactor (BWR) plant design and component behavior, as well as knowledge required to distinguish normal, abnormal, and ATWS accident conditions. The system was developed using a software tool environment for creating knowledge-based applications on a LISP machine. To facilitate prototype implementation and evaluation, a casual simulation of BWR shutdown sequences was developed and interfaced with the alarm system. An intelligent graphics interface for execution and control is described. System performance considerations and general observations relating to artificial intelligence application to nuclear power plant problems are provided

Analysis of Gamma Dose Rate Caused by Corrosion Products inside the Containment Building of Yonngwang Nuclear Power Plant Unit 3 During Shutdown Period

Energy Technology Data Exchange (ETDEWEB)

Ha, Wi Ho; Kim, Jae Cheon; Kim, Soon Young; Kim, Jong Kyung [Hanyang Univ., Seoul (Korea, Republic of)

2005-07-01

Occupational radiation exposure(ORE) of nuclear power plant(NPP) workers mainly occurs during the shutdown period. Major radioactive sources are the corrosion products released from the reactor coolant system(RCS). The corrosion products consist of circulating crud and deposited crud. Major radioactive corrosion products, {sup 58}Co and {sup 60}Co, are known to contribute approximately more than 70% of the total ORE. In this study, the corrosion products regarding cobalt were evaluated during the shutdown period, and gamma dose rates caused by them were calculated at the main working area inside the containment building of the Yonggwang NPP Unit 3.

Shutdown risk monitoring in TEPCO

International Nuclear Information System (INIS)

Sato, Hiroki; Masuda, Takahiro; Denda, Yasutaka; Yoneyama, Mitsuru; Imai, Shun-ichi; Miyata, Koichi

2009-01-01

At present, we are introducing risk monitors into our all three nuclear power stations; Fukushima Daiichi, Fukushima Daini and Kashiwazaki Kariwa, with technical support of TEPSYS. By monitoring shutdown risk of each unit, we are trying to optimize risks during outage inspection, and raising staff's awareness for reactor safety. This paper presents our recent shutdown risk monitoring activities in Fukushima Daiichi NPS. Shutdown risk monitoring has been carried out for the past five outages of Fukushima Daiichi NPS. Daily-changing shutdown risk is evaluated in the form of core damage frequency (CDF [/day/reactor]). We also examine high-risk point of outage plan if CDF is greater than the threshold at anytime of outage. The results are delivered to operational and maintenance staff before outage. The threshold value is set ten times as much as CDF of unit in operation. As CDF exceeds the threshold, we try to either change the system configuration, or let workers pay more attention to their works during the high-risk period. We already have some examples of outage plan modification to reduce CDF using the risk monitoring information. Greater number of station staff tends to pay more attention to shutdown risk thanks to these activities. (author)

TRIGA forced shutdowns analysis

International Nuclear Information System (INIS)

Negut, Gheorghe; Laslau, Florica

2008-01-01

The need for improving the operation leads us to use new methods and strategies. Probabilistic safety assessments and statistical analysis provide insights useful for our reactor operation. This paper is dedicated to analysis of the forced shutdowns during the first reactor operation period, between 1980 to 1989. A forced shutdown data base was designed using data on forced shutdowns collected from the reactor operation logbooks. In order to sort out the forced shutdowns the records have the following fields: - current number, date, equipment failed, failure type (M for mechanical, E for electrical, D for irradiation device, U for human factor failure; - scram mode, SE for external scram, failure of reactor cooling circuits and/or irradiation devices, SR for reactor scram, exceeding of reactor nuclear parameters, SB for reactor scram by control rod drop, SM for manual scram required by the abnormal reactor status; - scram cause, giving more information on the forced shutdown. This data base was processed using DBase III. The data processing techniques are presented. To sort out the data, one of the criteria was the number of scrams per year, failure type, scram mode, etc. There are presented yearly scrams, total operation time in hours, total unavailable time, median unavailable time period, reactor availability A. There are given the formulae used to calculate the reactor operational parameters. There are shown the scrams per year in the 1980 to 1989 period, the reactor operation time per year, the reactor shutdown time per year and the operating time versus down time per year. Total number of scrams in the covered period was 643 which caused a reactor down time of 4282.25 hours. In a table the scrams as sorted on the failure type is shown. Summarising, this study emphasized some problems and difficulties which occurred during the TRIGA reactor operation at Pitesti. One main difficulty in creating this data base was the unstandardized scram record mode. Some times

40 CFR 63.2852 - What is a startup, shutdown, and malfunction plan?

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 12 2010-07-01 2010-07-01 true What is a startup, shutdown, and... Production Compliance Requirements § 63.2852 What is a startup, shutdown, and malfunction plan? You must...)(2) malfunction period, or the § 63.2850(c)(2) or (d)(2) initial startup period. The SSM plan must...

Optimal shutdown management

International Nuclear Information System (INIS)

Bottasso, C L; Croce, A; Riboldi, C E D

2014-01-01

The paper presents a novel approach for the synthesis of the open-loop pitch profile during emergency shutdowns. The problem is of interest in the design of wind turbines, as such maneuvers often generate design driving loads on some of the machine components. The pitch profile synthesis is formulated as a constrained optimal control problem, solved numerically using a direct single shooting approach. A cost function expressing a compromise between load reduction and rotor overspeed is minimized with respect to the unknown blade pitch profile. Constraints may include a load reduction not-to-exceed the next dominating loads, a not-to-be-exceeded maximum rotor speed, and a maximum achievable blade pitch rate. Cost function and constraints are computed over a possibly large number of operating conditions, defined so as to cover as well as possible the operating situations encountered in the lifetime of the machine. All such conditions are simulated by using a high-fidelity aeroservoelastic model of the wind turbine, ensuring the accuracy of the evaluation of all relevant parameters. The paper demonstrates the capabilities of the novel proposed formulation, by optimizing the pitch profile of a multi-MW wind turbine. Results show that the procedure can reliably identify optimal pitch profiles that reduce design-driving loads, in a fully automated way

Optimal shutdown management

Science.gov (United States)

Bottasso, C. L.; Croce, A.; Riboldi, C. E. D.

2014-06-01

The paper presents a novel approach for the synthesis of the open-loop pitch profile during emergency shutdowns. The problem is of interest in the design of wind turbines, as such maneuvers often generate design driving loads on some of the machine components. The pitch profile synthesis is formulated as a constrained optimal control problem, solved numerically using a direct single shooting approach. A cost function expressing a compromise between load reduction and rotor overspeed is minimized with respect to the unknown blade pitch profile. Constraints may include a load reduction not-to-exceed the next dominating loads, a not-to-be-exceeded maximum rotor speed, and a maximum achievable blade pitch rate. Cost function and constraints are computed over a possibly large number of operating conditions, defined so as to cover as well as possible the operating situations encountered in the lifetime of the machine. All such conditions are simulated by using a high-fidelity aeroservoelastic model of the wind turbine, ensuring the accuracy of the evaluation of all relevant parameters. The paper demonstrates the capabilities of the novel proposed formulation, by optimizing the pitch profile of a multi-MW wind turbine. Results show that the procedure can reliably identify optimal pitch profiles that reduce design-driving loads, in a fully automated way.

Shutdown problems in large tokamaks

International Nuclear Information System (INIS)

Weldon, D.M.

1978-01-01

Some of the problems connected with a normal shutdown at the end of the burn phase (soft shutdown) and with a shutdown caused by disruptive instability (hard shutdown) have been considered. For a soft shutdown a cursory literature search was undertaken and methods for controlling the thermal wall loading were listed. Because shutdown computer codes are not widespread, some of the differences between start-up codes and shutdown codes were discussed along with program changes needed to change a start-up code to a shutdown code. For a hard shutdown, the major problems are large induced voltages in the ohmic-heating and equilibrium-field coils and high first wall erosion. A literature search of plasma-wall interactions was carried out. Phenomena that occur at the plasma-wall interface can be quite complicated. For example, material evaporated from the wall can form a virtual limiter or shield protecting the wall from major damage. Thermal gradients that occur during the interaction can produce currents whose associated magnetic field also helps shield the wall

Safety considerations for research reactors in extended shutdown

International Nuclear Information System (INIS)

2004-01-01

According to the IAEA Research Reactor Database, in the last 20 years, 367 research reactors have been shut down. Of these, 109 have undergone decommissioning and the rest are in extended shutdown with no clear definition about their future. Still other research reactors are infrequently operated with no meaningful utilization programme. These two situations present concerns related to safety such as loss of corporate memory, personnel qualification, maintenance of components and systems and preparation and maintenance of documentation. There are many reasons to shut down a reactor; these may include: - the need to carry out modifications in the reactor systems; - the need for refurbishment to extend the lifetime of the reactor; - the need to repair reactor structures, systems, or components; - the need to remedy technical problems; - regulatory or public concerns; - local conflicts or wars; - political convenience; - the lack of resources. While any one of these reasons may lead to shutdown of a reactor, each will present unique problems to the reactor management. The large variations from one research reactor to the next also will contribute to the uniqueness of the problems. Any option that the reactor management adopts will affect the future of the facility. Options may include dealing with the cause of the shutdown and returning to normal operation, extending the shutdown period waiting a future decision, or decommissioning. Such options are carefully and properly analysed to ensure that the solution selected is the best in terms of reactor type and size, period of shutdown and legal, economic and social considerations. This publication provides information in support of the IAEA safety standards for research reactors

Man machine interface and its implementation

International Nuclear Information System (INIS)

Hills, B.G.; Boettcher, D.B.; Reed, R.

1992-01-01

Sizewell B is the latest nuclear power station to be constructed in the United Kingdom: its Man-Machine Interfaces are therefore, by definition, the state-of-the-art. This paper discusses the principal Man-Machine Interfaces used in the operation of the station, and the systems that implement them. The Man-Machine Interface facilities discussed are: in the Main Control Room, which is used for normal operation and shutdown of the plant: in the Auxiliary Shutdown Room, which allows shutdown of the reactor if evacuation of the main Control Room is necessary: and in the Technical Support Centre, which is used for remote monitoring of the plant. The Man-Machine Interfaces that are described are parts of a station-wide group of interlinked computer systems called the Data Processing and Control System. This system collects data from the plant and displays it to the operators via discrete devices and on graphical computer displays. It also acquires control inputs from the operators via switches, which are then used to provide remote manual control, modulating control and sequence control. The computer system that handles the plant process data and alarm information displays uses a windowing interface with keyboard and trackerball navigation to allow easy retrieval and viewing of information. It is this system that is the main topic of this paper. (author)

Nuclear reactor unit shutdown planning

International Nuclear Information System (INIS)

Gardais, J.P.

1994-01-01

In order to optimize the reactor maintenance shutdown efficiency and the reactor availability, an audit had been performed on the shutdown organization at EDF: management, skills, methods and experience feedback have been evaluated; several improvement paths have been identified: project management, introduction of shutdown management professionals, shutdown permanent industrialization, and experience feedback engineering

Supplementary shutdown system of 220 MWe standard PHWR in India

International Nuclear Information System (INIS)

Muktibodh, U.C.

1997-01-01

The design objective of the shutdown system is to make the reactor subcritical and hold it in that state for an extended period of time. This objective must be realised under all anticipated operational occurrences and postulated abnormal conditions even during most reactive state of the core. PHWR design criteria for shutdown stipulates requirement of two independent diverse and fast acting shutdown systems, either of which acting alone should meet the above objectives. This requirement would normally call for a large number of reactivity mechanism penetrations into the calandria. From the point of view of space availability at the reactivity mechanism area on top of calandria, for the relatively small core of 220 MWe PHWRs, and ease of maintenance realisation of the total worth by either of the shutdown systems acting alone was difficult. To overcome this engineering constraint and at the same time to satisfy the design criteria, a unique approach to meet the reactivity demands for shutdown was adopted. The reactivity requirements of the shutdown consists of fast and slow reactivity changes. For the shutdown system of 220 MWe PHWRs, the approach of realizing fast reactivity changes with dual redundant, diverse, fast acting shutdown systems aided by a slow acting shutdown system to counter delayed reactivity changes was conceived. The supplementary slow acting shutdown system is called upon to act after actuation of either of the two redundant fast acting systems and is referred to as Liquid Poison Injection System (LPIS). The system adds bulk amount of neutron poison (boric acid), equivalent to 45 mk, directly into the moderator through two nozzles in calandria using pneumatic pressure. This paper describes the design of LPIS as envisaged for the standardised 220 MWe PHWRs. (author)

Shutdown Safety in NEK

International Nuclear Information System (INIS)

Gluhak, Mario; Senegovic, Marko

2014-01-01

Industry performance analysis since 2004 has revealed that 23% of the events reported to WANO occurred during outage periods. Given the fact that a plant is in the outage only 5 percent of the time, this emphasizes the importance of shutdown safety and measures station staffs undertake to maintain effective barriers to safety margins during the outage. Back in 1990s, the industry adopted guidance to meet safety requirements by focusing on safety functions. Both WANO and INPO released various documents, reports and guidelines to help accomplish those requirements. However, in the last decade inadequate 'defence in depth' has led to several events affecting shutdown safety and challenging one of the most important nuclear safety principles: 'The special characteristics of nuclear technology are taken into account in all decisions and actions. Reactivity control, continuity of core cooling, and integrity of fission product barriers are valued as essential, distinguishing attributes of nuclear station work environment'. NEK has recognized the importance of 'defence in depth'Industry performance analysis since 2004 has revealed that 23% of the events reported to WANO occurred during outage periods. Given the fact that a plant is in the outage only 5 percent of the time, this emphasizes the importance of shutdown safety and measures station staffs undertake to maintain effective barriers to safety margins during the outage. Back in 1990s, the industry adopted guidance to meet safety requirements by focusing on safety functions. Both WANO and INPO released various documents, reports and guidelines to help accomplish those requirements. However, in the last decade inadequate 'defence in depth' has led to several events affecting shutdown safety and challenging one of the most important nuclear safety principles: 'The special characteristics of nuclear technology are taken into account in all decisions and actions. Reactivity

CANDU passive shutdown systems

Energy Technology Data Exchange (ETDEWEB)

Hart, R S; Olmstead, R A [AECL CANDU, Sheridan Park Research Community, Mississauga, ON (Canada)

1996-12-01

CANDU incorporates two diverse, passive shutdown systems, independent of each other and from the reactor regulating system. Both shutdown systems function in the low pressure, low temperature, moderator which surrounds the fuel channels. The shutdown systems are functionally different, physically separate, and passive since the driving force for SDS1 is gravity and the driving force for SDS2 is stored energy. The physics of the reactor core itself ensures a degree of passive safety in that the relatively long prompt neutron generation time inherent in the design of CANDU reactors tend to retard power excursions and reduces the speed required for shutdown action, even for large postulated reactivity increases. All passive systems include a number of active components or initiators. Hence, an important aspect of passive systems is the inclusion of fail safe (activated by active component failure) operation. The mechanisms that achieve the fail safe action should be passive. Consequently the passive performance of the CANDU shutdown systems extends beyond their basic modes of operation to include fail safe operation based on natural phenomenon or stored energy. For example, loss of power to the SDS1 clutches results in the drop of the shutdown rods by gravity, loss of power or instrument air to the injection valves of SDS2 results in valve opening via spring action, and rigorous self checking of logic, data and timing by the shutdown systems computers assures a fail safe reactor trip through the collapse of a fluctuating magnetic field or the discharge of a capacitor. Event statistics from operating CANDU stations indicate a significant decrease in protection system faults that could lead to loss of production and elimination of protection system faults that could lead to loss of protection. This paper provides a comprehensive description of the passive shutdown systems employed by CANDU. (author). 4 figs, 3 tabs.

Analysis of HFETR shut-down state caused by loss of off-site power supply

International Nuclear Information System (INIS)

Wang Jinghu

1997-01-01

During the last 15 years, there are more than 40 unplanned shut-downs caused by loss of off-site power in HFETR. Because HFETR is a special research reactor, the author describes the shut-down state as three period. The author also discusses the influence of the number of shut-down due to loss of off-site power supply on the reactor safety, and propose some suggestions and measures to reduce the effects

Probabilistic analysis of 900 MWe PWR. Shutdown technical specifications

International Nuclear Information System (INIS)

Mattei, J.M.; Bars, G.

1987-11-01

During annual shutdown, preventive maintenance and modifications which are made on PWRs cause scheduled unavailabilities of equipment or systems which might harm the safety of the installation, in spite of the low level of decay heat during this period. The pumps in the auxiliary feedwater system, component cooling water system, service water system, the water injection arrays (LPIS, HPIS, CVCS), and the containment spray system may have scheduled unavailability, as well as the power supply of the electricity boards. The EDF utility is aware of the risks related to these situations for which accident procedures have been set up and hence has proposed limiting downtime for this equipment during the shutdown period, through technical specifications. The project defines the equipment required to ensure the functions important for safety during the various shutdown phases (criticality, water inventory, evacuation of decay heat, containment). In order to be able to judge the acceptability of these specifications, the IPSN, the technical support of the Service Central de Surete des Installations Nucleaires, has used probabilistic methodology to analyse the impact on the core melt probability of these specifications, for a French 900 MWe PWR

RECAP, Replacement Energy Cost for Short-Term Reactor Plant Shut-Down

International Nuclear Information System (INIS)

VanKuiken, J.C.; Daun, C.J.; Jusko, M.J.

1995-01-01

1 - Description of program or function: RECAP (Replacement Energy Cost Analysis Package) determines the replacement energy costs associated with short-term shutdowns or de-ratings of one or more nuclear reactors. Replacement energy cost refers to the change in generating-system production cost that results from shutting down a reactor. The cost calculations are based on the seasonal, unit-specific cost estimates for 1988-1991 for all 117 nuclear electricity-generating units in the U.S. RECAP is menu-driven, allowing the user to define specific case studies in terms of parameters such as the units to be included, the length and timing of the shutdown or de-rating period, the unit capacity factors, and the reference year for reporting cost results. In addition to simultaneous shutdown cases, more complicated situations, such as overlapping shutdown periods or shutdowns that occur in different years, can be examined through use of a present-worth calculation option. 2 - Method of solution: The user selects a set of units for analysis, defines a shutdown (or de-rating) period, and specifies any planned maintenance outages, delays in unit start-ups, or changes in default capacity factors. The program then determines which seasonal cost numbers to apply, estimates total and daily costs, and makes the appropriate adjustments for multiple outages if they are encountered. The change in production cost is determined from the difference between the total variable costs (variable fuel cost, variable operation and maintenance cost, and purchased energy cost) when the reactor is available for generation and when it is not. Changes in reference-year dollars are based on gross national product (GNP) price deflators or on optional use inputs. Once RECAP has completed the initial cost estimates for a case study (or series of case studies), present-worth analysis can be conducted using different reference-year dollars and discount rates, as specified by the user. The program uses

Reactor shutdown device

International Nuclear Information System (INIS)

Inoue, Toyokazu.

1982-01-01

Purpose: To obtain a highly reliable reactor shutdown device capable of checking its function irrespective of the state whether shutdown or operation in a gas-cooled type reactor. Constitution: A hopper is disposed above a guide tube inserted into the reactor core and particulate neutron absorbers are contained in the hopper. An opening for falling particles is disposed to the bottom of the hopper in opposition to the upper end of the guide pipe and the opening is closed by a plug suspended by way of a weld line so as to be capable of dropping. A power source for supplying electrical current to the weld line is disposed. Accordingly, if the current is supplied to the weld line, the line is cut by welding to fall the plug so that the neutron-absorbing particles fall from the opening into the guide pipe to shutdown the reactor, whereby high reliability is obtained for the operation. (Seki, T.)

Shutdown Chemistry Process Development for PWR Primary System

Energy Technology Data Exchange (ETDEWEB)

Sung, K.B. [Korea Electric Power Research Institute, Taejeon (Korea, Republic of)

1997-12-31

This study report presents the shutdown chemistry of PWR primary system to reduce and remove the radioactive corrosion products which were deposited on the nuclear fuel rods surface and the outside of core like steam generator channel head, RCS pipings etc. The major research results are the follows ; the deposition radioactive mechanism of corrosion products, the radiochemical composition, the condition of coolant chemistry to promote the dissolution of radioactive cobalt and nickel ferrite, the control method of dissolved hydrogen concentration in the coolant by the mechanical and chemical methods. The another part of study is to investigate the removal characteristics of corrosion product ions and particles by the demineralization system to suggest the method which the system could be operate effectively in shut-down purification period. (author). 19 refs., 25 figs., 48 tabs.

Improvements of primary coolant shutdown chemistry and reactor coolant system cleanup

International Nuclear Information System (INIS)

Gaudard, G.; Gilles, B.; Mesnage, F.; Cattant, F.

2002-01-01

In the framework of a radiation exposure management program entitled >, EDF aims at decreasing the mass dosimetry of nuclear power plants workers. So, the annual dose per unit, which has improved from 2.44 m.Sv in 1991 to 1.08 in 2000, should target 0.8 mSv in the year 2005 term in order to meet the results of the best nuclear operators. One of the guidelines for irradiation source term reduction is the optimization of operation parameters, including reactor coolant system (RCS) chemistry in operation, RCS shutdown chemistry and RCS cleanup improvement. This paper presents the EDF strategy for the shutdown and start up RCS chemistry optimization. All the shutdown modes have been reviewed and for each of them, the chemical specifications will be fine tuned. A survey of some US PWRs shutdown practices has been conducted for an acid and reducing shutdown chemistry implementation test at one EDF unit. This survey shows that deviating from the EPRI recommended practice for acid and reducing shutdown chemistry is possible and that critical path impact can be minimized. The paper also presents some investigations about soluble and insoluble species behavior and characterization; the study focuses here on 110m Ag, 122 Sb, 124 Sb and iodine contamination. Concerning RCS cleanup improvement, the paper presents two studies. The first one highlights some limited design modifications that are either underway or planned, for an increased flow rate during the most critical periods of the shutdown. The second one focuses on the strategy EDF envisions for filters and resins selection criteria. Matching the study on contaminants behavior with the study of filters and resins selection criteria should allow improving the cleanup efficiency. (authors)

Shutdown and low-power operation at commercial nuclear power plants in the United States

International Nuclear Information System (INIS)

1993-09-01

The report contains the results of the NRC Staff's evaluation of shutdown and low-power operations at US commercial nuclear power plants. The report describes studies conducted by the staff in the following areas: Operating experience related to shutdown and low-power operations, probabilistic risk assessment of shutdown and low-power conditions and utility programs for planning and conducting activities during periods the plant is shut down. The report also documents evaluations of a number of technical issues regarding shutdown and low-power operations performed by the staff, including the principal findings and conclusions. Potential new regulatory requirements are discussed, as well as potential changes in NRC programs. A draft report was issued for comment in February 1992. This report is the final version and includes the responses to the comments along with the staff regulatory analysis of potential new requirements

Magnetic disconnect for secondary shutdown

International Nuclear Information System (INIS)

Lessor, D.L.

1972-01-01

A description is given of studies to develop a magnetic holding clutch in the control rod drive line as an alternate shutdown device for the FFTF. Results indicate that a three-phase disconnect, hold, and backup shutdown system can be designed to operate satisfactorily. (U.S.)

Does debt ceiling and government shutdown help in forecasting the us equity risk premium?

Directory of Open Access Journals (Sweden)

Aye Goodness C.

2016-01-01

Full Text Available This article evaluates the predictability of the equity risk premium in the United States by comparing the individual and complementary predictive power of macroeconomic variables and technical indicators using a comprehensive set of 16 economic and 14 technical predictors over a monthly out-ofsample period of 1995:01 to 2012:12 and an in-sample period of 1986:01- 1994:12. In order to do so we consider, in addition to the set of variables used in Christopher J. Neely et al. (2013 and using a more recent dataset, the forecasting ability of two other important variables namely government shutdown and debt ceiling. Our results show that one of the newly added variables namely government shutdown provides statistically significant out-of-sample predictive power over the equity risk premium relative to the historical average. Most of the variables, including government shutdown, also show significant economic gains for a risk averse investor especially during recessions.

Human factors evaluation of man-machine interface for periodic safety review of nuclear power plants

International Nuclear Information System (INIS)

Lee, Yong Hee; Lee, Jung Woon; Park, Jae Chang; Hwang, In Koo; Lee, Hyun Cheol; Jang, Tong Il; Ku, Jin Young; Kim, Soo Jin

2004-12-01

This report describes the research results of human factors assessment on the MMI(Man Machine Interface) equipment as part of Periodic Safety Review(PSR) of Nuclear Power Plants(NPPs). As MMI is a key factor among human factors to be reviewed in PSR, we reviewed the MMI components of nuclear power plants in aspect of human factors engineering. The availability, suitability, and effectiveness of the MMI devices were chosen to be reviewed. The MMI devices were investigated through the review of design documents related to the MMI, survey of control panels, evaluation of experts, and experimental assessment. Checklists were used to perform this assessment and record the review results. The items mentioned by the expert comments to review in detail in relation with task procedures were tested by experiments with operators' participation. For some questionable issues arisen during this MMI review, operator workload and possibility of errors in operator actions were analysed. The reviewed MMI devices contain MCR(Main Control Room), SPDS(Safety Parameter Display System), RSP(Remote Shutdown Panel), and the selected LCBs(Local Control Boards) importantly related to safety. As results of the assessments, any significant problem challenging the safety was not found on human factors in the MMI devices. However, several small items to be changed and improved in suitability of MMI devices were discovered. An action plan is recommended to accommodate the suggestions and review comments. It will enhance the plant safety on MMI area

Proceedings of workshop on reactor shutdown system

International Nuclear Information System (INIS)

1997-03-01

India has gained considerable experience in design, development, construction and operation of research and power reactors during the last four decades. Reactor shutdown system (RSS) is the most important engineered safety system of any reactor. A lot of technological developments have taken place to improve the reactor shutdown systems, particularly with advancement in reliability analysis and instrumentation and control. If the reactor is not shutdown, the fuel may melt, releasing radioactivity and possibly reactivity addition as in the case of Fast Breeder Reactor (FBR). Apart from radiological safety consequences, large investment has to be written off. The function of the RSS is to stop fission chain reaction and prevent breach of fuel. The design of RSS is multidisciplinary. It requires reactor physics analysis, design of absorber rods, drive mechanisms, safety logic to order shutdown and instrumentation to detect unsafe conditions. High reliability is essential and this requires two independent shutdown systems. This book contains the proceedings of the workshop on reactor shutdown system and papers relevant to INIS are indexed separately

Simulation of Darlington shutdown and regulation systems

International Nuclear Information System (INIS)

1986-10-01

This report describes the development of a simulation of the Darlington Nuclear Generating Station shutdown and regulating systems, DARSIM. The DARSIM program simulates the spatial neutron dynamics, the regulation of the reactor power, and Shutdown System 1, SDS1, and Shutdown System 2, SDS2, software. The DARSIM program operates in the interactive simulation (INSIM) program environment

Identification of passive shutdown system parameters in a metal fueled LMR

International Nuclear Information System (INIS)

Vilim, R.B.

1992-01-01

This document discusses periodic testing of the passive shutdown system in a metal fueled liquid metal reactor which has been proposed as a Technical Specification requirement. In the approach to testing considered in this paper, perturbation experiments performed at normal operation are used to predict an envelope that bounds reactor response to flowrate, inlet temperature and external reactivity forcing functions. When the envelope for specific upsets lies within safety limits, one concludes that the passive shutdown system is operation properly for those upsets. Simulation results for the EBR-II reactor show that the response envelope for loss of flow and rod reactivity insertion events does indeed bound these events

Safety shutdown separators

Science.gov (United States)

Carlson, Steven Allen; Anakor, Ifenna Kingsley; Farrell, Greg Robert

2015-06-30

The present invention pertains to electrochemical cells which comprise (a) an anode; (b) a cathode; (c) a solid porous separator, such as a polyolefin, xerogel, or inorganic oxide separator; and (d) a nonaqueous electrolyte, wherein the separator comprises a porous membrane having a microporous coating comprising polymer particles which have not coalesced to form a continuous film. This microporous coating on the separator acts as a safety shutdown layer that rapidly increases the internal resistivity and shuts the cell down upon heating to an elevated temperature, such as 110.degree. C. Also provided are methods for increasing the safety of an electrochemical cell by utilizing such separators with a safety shutdown layer.

ORNL Isotopes Facilities Shutdown Program Plan

International Nuclear Information System (INIS)

Gibson, S.M.; Patton, B.D.; Sears, M.B.

1990-10-01

This plan presents the results of a technical and economic assessment for shutdown of the Oak Ridge National Laboratory (ORNL) isotopes production and distribution facilities. On December 11, 1989, the Department of Energy (DOE), Headquarters, in a memorandum addressed to DOE Oak Ridge Operations Office (DOE-ORO), gave instructions to prepare the ORNL isotopes production and distribution facilities, with the exception of immediate facility needs for krypton-85, tritium, and yttrium-90, for safe shutdown. In response to the memorandum, ORNL identified 17 facilities for shutdown. Each of these facilities is located within the ORNL complex with the exception of Building 9204-3, which is located at the Y-12 Weapons Production Plant. These facilities have been used extensively for the production of radioactive materials by the DOE Isotopes Program. They currently house a large inventory of radioactive materials. Over the years, these aging facilities have inherited the problems associated with storing and processing highly radioactive materials (i.e., facilities' materials degradation and contamination). During FY 1990, ORNL is addressing the requirements for placing these facilities into safe shutdown while maintaining the facilities under the existing maintenance and surveillance plan. The day-to-day operations associated with the surveillance and maintenance of a facility include building checks to ensure that building parameters are meeting the required operational safety requirements, performance of contamination control measures, and preventative maintenance on the facility and facility equipment. Shutdown implementation will begin in FY 1993, and shutdown completion will occur by the end of FY 1994

Design philosophy of PFBR shutdown systems

International Nuclear Information System (INIS)

Rajan Babu, V.; Vijayashree, R.; Govindarajan, S.; Vaidyanathan, G.; Muralikrishna, G.; Shanmugam, T.K.; Chetal, S.C.; Raghavan, K.; Bhoje, S.B.

1996-01-01

This paper presents the overall design philosophy of shutdown system of 500 MWe Prototype Fast Breeder Reactor (PFBR). It discusses design criteria, parameters calling for safety action, different safety actions and the concepts conceived for shutdown systems. In tune with the philosophy of defence-in-depth, additional passive shutdown features, viz., Self Actuating Device (SADE) and Curie Point Magnetic (CPM) switch and protective feature like absorber rod Stroke Limiting Device (SLD) are contemplated. It also discusses about suitability of Gas Expansion Module (GEM) as one of the safety devices in PFBR. (author). 3 refs, 3 figs, 1 tab

Action plan during reactor shutdown in October 1965, Annex 5; Prilog br. 5 - Plan radova u toku stajanja reaktora u mesecu oktobru 1965. godine

Energy Technology Data Exchange (ETDEWEB)

Nikolic, M [Reaktor RA, Odelenje odrzavanja, Institute of Nuclear Sciences Boris Kidric, Vinca, Beograd (Serbia and Montenegro)

1965-12-15

The action plan of the division for reactor maintenance during reactor shutdown includes detailed list of tasks for mechanics, electronic and electrical equipment group during the reactor shutdown period in October 1965. It contains tasks for planned shutdown periods in September, August, July, May, April, March, and February 1965. [Serbo-Croat] Plan radova Odelenja odrzavanja reaktora RA za period stajanja reaktora u oktobru mesecu 1965. sadrzi detaljnu listu zadataka masinske grupe, elektro grupe i elektronske grupe. Ovaj prilog sadrzi i zadatke koji ce biti obavljeni tokom planiranih perioda kada je reaktor zaustavljen u septembru, avgustu, julu, junu, maju, aprilu, martu i februaru 1965.

The use of digital computers in CANDU shutdown systems

International Nuclear Information System (INIS)

Gilbert, R.S.; Komorowski, C.W.

1986-01-01

This paper summarizes the application of computers in CANDU shutdown systems. A general description of systems that are already in service is presented along with a description of a fully computerized shutdown system which is scheduled to enter service in 1987. In reviewing the use of computers in the shutdown systems there are three functional areas where computers have been or are being applied. These are (i) shutdown system monitoring, (ii) parameter display and testing and (iii) shutdown initiation. In recent years various factors (References 1 and 2) have influenced the development and deployment of systems which have addressed two of these functions. At the present time a system is also being designed which addresses all of these areas in a comprehensive manner. This fully computerized shutdown system reflects the previous design, and licensing experience which was gained in earlier applications. Prior to describing the specific systems which have been designed a short summary of CANDU shutdown system characteristics is presented

Elementary calculation of the shutdown delay of a pile; Calcul elementaire de la periode d'extinction d'une pile

Energy Technology Data Exchange (ETDEWEB)

Yvon, J

1949-04-01

This study analyzes theoretically the progress of the shutdown of a nuclear pile (reactor) when a cadmium rod is introduced instantaneously. For simplification reasons, the environment of the pile is considered as homogenous and only thermal neutrons are considered (delayed neutrons are neglected). Calculation is made first for a plane configuration (plane vessel, plane multiplier without reflector, and plane multiplier with reflector), and then for a cylindrical configuration (multiplier without reflector, multiplier with infinitely thick reflector, finite cylindrical piles without reflector and with reflector). The self-sustain conditions are calculated for each case and the multiplication length and the shutdown delay are deduced. (J.S.)

Reliability analysis of shutdown system

International Nuclear Information System (INIS)

Kumar, C. Senthil; John Arul, A.; Pal Singh, Om; Suryaprakasa Rao, K.

2005-01-01

This paper presents the results of reliability analysis of Shutdown System (SDS) of Indian Prototype Fast Breeder Reactor. Reliability analysis carried out using Fault Tree Analysis predicts a value of 3.5 x 10 -8 /de for failure of shutdown function in case of global faults and 4.4 x 10 -8 /de for local faults. Based on 20 de/y, the frequency of shutdown function failure is 0.7 x 10 -6 /ry, which meets the reliability target, set by the Indian Atomic Energy Regulatory Board. The reliability is limited by Common Cause Failure (CCF) of actuation part of SDS and to a lesser extent CCF of electronic components. The failure frequency of individual systems is -3 /ry, which also meets the safety criteria. Uncertainty analysis indicates a maximum error factor of 5 for the top event unavailability

Maintenance, repair and operation (MRO) of shutdown facilities

International Nuclear Information System (INIS)

Kenny, S.

2006-01-01

What level of maintenance does one apply to a shutdown facility? Well it depends on who you ask. Operations staff sees facilities that have completed their useful life cycle as a cost drain while Decommissioning staff sees this as the start of a new life cycle. Based on the decommissioning plan for the particular facility the building could complete another full life cycle while under decommissioning whether it is in storage with surveillance mode or under active decommissioning. This paper will explore how you maintain a facility and systems for many years after its useful life until final decommissioning is completed. When a building is declared redundant, who looks after it until the final decommissioning end state is achieved? At the AECL, Chalk River Labs site the safe shutdown and turnover process is one key element that initiates the decommissioning process. The real trick is orchestrating maintenance, repair and operation plans for a facility that has been poorly invested in during its last years of useful life cycle. To add to that usually shutdowns are prolonged for many years beyond the expected turnover period. During this presentation I will cover what AECL is doing to ensure that the facilities are maintained in a proper state until final decommissioning can be completed. All facilities or systems travel through the same life cycle, design, construction, commissioning, operation, shutdown and demolition. As we all know, nuclear facilities add one more interesting twist to this life cycle called Decommissioning that lands between shutdown and demolition. As a facility nears the shutdown phase, operations staff loose interest in the facility and stop investing in upgrades, repairs and maintenance but continue to invest and focus on maximizing operations. Facility maintenance standards produced by the International Facility Maintenance Association (IFMA) based on a survey done every year state that 2.2% of the total operating costs for the site should be

Failure of PWR-RHRS under cold shutdown conditions: Experimental results from the PKL test facility

International Nuclear Information System (INIS)

Mandl, R.M.; Umminger, K.J.; Logt, J.V.D.

1991-01-01

The Residual Heat Removal System (RHRS) of a PWR is designed to transfer thermal energy from the core after plant shutdown and maintain the plant in cold shutdown or refuelling conditions for extended periods of time. Initial reactor cooling after shutdown is achieved by dissipating heat through the steam generators (SGs) and discharging steam to the condenser by means of the Turbine Bypass System (TBS). When the reactor coolant temperature has dropped to about 160C and pressure has been reduced to 30 bar the RHRS is placed into operation. it reduces the coolant temperature to 50C within 20 hours after shutdown. The time margin for establishing alternate methods of heat removal following a failure of the RHRS depends on the Reactor Coolant System (RCS) temperature, the decay heat rate and the amount of RCS inventory. During some shutdown operations the RCS may be partially drained (e. g. to perform SG inspections). Decreased primary system inventory can significantly reduce the time available to recover the RHRS's function prior to bulk boiling and possible core uncovery. In the PKL test facility, which simulates a 1,300 MWe 4-loop PWR on a scale 1:145, a failure of RHRS under cold shutdown conditions was performed. This presentation gives a brief description of the test facility followed by the test objectives and results of this experiment

Plasma shutdown device

International Nuclear Information System (INIS)

Hosogane, Nobuyuki; Nakayama, Takahide.

1985-01-01

Purpose: To prevent concentration of plasma currents to the plasma center upon plasma shutdown in a torus type thermonuclear device by the injection of fuels to the plasma center thereby prevent plasma disruption at the plasma center. Constitution: The plasma shutdown device comprises a plasma current measuring device that measures the current distribution of plasmas confined within a vacuum vessel and outputs a control signal for cooling the plasma center when the plasma currents concentrate to the plasma center and a fuel supply device that supplies fuels to the plasma center for cooling the center. The fuels are injected in the form of pellets into the plasmas. The direction and the velocity of the injection are set such that the pellets are ionized at the center of the plasmas. (Horiuchi, T.)

Human Factors Evaluation of Man-Machine Interface for Periodic Safety Review of Yonggwang Unit no. 1, 2

International Nuclear Information System (INIS)

Lee, Yong Hee; Lee, Jung Woon; Park, Jae Chang

2006-01-01

This report describes the research results of human factors assessment on the MMI(Man Machine Interface) equipment as part of Periodic Safety Review(PSR) of Yonggwang Unit no. 1, 2. As MMI is a key factor among human factors to be reviewed in PSR, we reviewed the MMI components of nuclear power plants in aspect of human factors engineering. The availability, suitability, and effectiveness of the MMI devices were chosen to be reviewed. The MMI devices were investigated through the review of design documents related to the MMI, survey of control panels, evaluation of experts, and experimental assessment. Checklists were used to perform this assessment and record the review results. The items mentioned by the expert comments to review in detail in relation with task procedures were tested by experiments with operators' participation. For some questionable issues arisen during this MMI review, operator workload and possibility of errors in operator actions were analysed. The reviewed MMI devices contain MCR(Main Control Room), SPDS(Safety Parameter Display System), RSP(Remote Shutdown Panel), and the selected LCBs(Local Control Boards) importantly related to safety. As results of the assessments, any significant problem challenging the safety was not found on human factors in the MMI devices. However, several small items to be changed and improved in suitability of MMI devices were discovered. An action plan is recommended to accommodate the suggestions and review comments. It will enhance the plant safety on MMI area

Human Factors Evaluation of Man-Machine Interface for Periodic Safety Review of Yonggwang Unit no. 1, 2

Energy Technology Data Exchange (ETDEWEB)

Lee, Yong Hee; Lee, Jung Woon; Park, Jae Chang (and others)

2006-01-15

This report describes the research results of human factors assessment on the MMI(Man Machine Interface) equipment as part of Periodic Safety Review(PSR) of Yonggwang Unit no. 1, 2. As MMI is a key factor among human factors to be reviewed in PSR, we reviewed the MMI components of nuclear power plants in aspect of human factors engineering. The availability, suitability, and effectiveness of the MMI devices were chosen to be reviewed. The MMI devices were investigated through the review of design documents related to the MMI, survey of control panels, evaluation of experts, and experimental assessment. Checklists were used to perform this assessment and record the review results. The items mentioned by the expert comments to review in detail in relation with task procedures were tested by experiments with operators' participation. For some questionable issues arisen during this MMI review, operator workload and possibility of errors in operator actions were analysed. The reviewed MMI devices contain MCR(Main Control Room), SPDS(Safety Parameter Display System), RSP(Remote Shutdown Panel), and the selected LCBs(Local Control Boards) importantly related to safety. As results of the assessments, any significant problem challenging the safety was not found on human factors in the MMI devices. However, several small items to be changed and improved in suitability of MMI devices were discovered. An action plan is recommended to accommodate the suggestions and review comments. It will enhance the plant safety on MMI area.

Reactor shutdown system of prototype fast breeder reactor

International Nuclear Information System (INIS)

Govindarajan, S.; Singh, Om Pal; Kasinathan, N.; Paramasivan Pillai, C.; Arul, A.J.; Chetal, S.C.

2002-01-01

Full text: The shutdown system of PFBR is designed to assure a very high reliability by employing well known principles of redundancy, diversity and independence. The failure probability of the shutdown system limited to -6 / ry. Salient features of the shutdown system are: Two independent shutdown systems, each of them able to accommodate an additional single failure and made up of a trip system and an associated absorber rod group. Diversity between trip systems, rods and mechanisms. Initiation of SCRAM by two diverse physical parameters of the two shutdown systems for design events leading potentially to unacceptable conditions is the core. The first group of nine rods called control and safety rods (CSR) is used for both shutdown as well as power regulation. The second group consisting of three rods known as diverse safety rods (DSR) is used only for shutdown. Diversity between the two groups is ensured by varying the operating conditions of the electromagnets and the configurations of the mobile parts. The reactivity worth of the absorber rods have been chosen such that each group of rods would ensure cold shutdown on SCRAM even when the most reactive rod of the group fails to drop. Together the two groups ensure a shutdown margin of 5000 pcm. The speed and individual rod worth of the CSR is chosen from operational and safety considerations during reactor start up and raising of power. Required drop time of rods during SCRAM depends on the incident considered. For a severe reactivity incident of 3 $/s this has to be limited to 1s and is ensured by limiting electromagnet response time and facilitating drop by gravity. Design safety limits for core components have been determined and SCRAM parameters have been identified by plant dynamic analysis to restrict the temperatures of core components within the limits. The SCRAM parameters are distributed between the two systems appropriately. Fault tree analysis of the system has been carried out to determine the

LMFBR self-activated shutdown systems

International Nuclear Information System (INIS)

Sowa, E.S.; Barthold, W.P.; Eggen, D.T.; Huebotter, P.R.; Josephson, J.; Pizzica, P.A.; Turski, R.B.; van Erp, J.B.

1976-01-01

Self-actuated shutdown systems (SASSs), fully contained within the dimensions of a fuel subassembly and installed in the core in judiciously chosen locations, can provide an important additional safety feature for LMFBRs. If actuated by phenomena inherent to the system and its immediate environment, these systems can contribute considerably to the total reliability of the overall plant protection system, in particular as regards protection against human error. It was shown that this type of shutdown system is capable of inserting a substantial amount of negative reactivity into the core with a relatively small impact on plant performance. Furthermore, it was shown that a coolable geometry can be maintained in LMFBRs of current design for a wide spectrum of accident initiators, and for a range of response times and insertion rates which appear to be achievable within practical design limits. Experiments showed that Curie-point-operated devices have considerable promise for application in self-actuated shutdown systems, in particular as regards meeting the requirements of testability and resettability

Ground loops detection system in the RFX machine

International Nuclear Information System (INIS)

Bellina, F.; Pomaro, N.; Trevisan, F.

1996-01-01

RFX is a toroidal machine for the fusion research based on the RFP configuration. During the pulse, in any conductive loop close to the machine very strong currents can be induced, which may damage the diagnostics and the other instrumentation. To avoid loops, the earthing system of the machine is tree-shaped. However, an accidental contact between metallic earthed masses of the machine may give rise to an unwanted loop as well. An automatic system for the detection of ground loops in the earthing system has therefore been developed, which works continuously during shutdown intervals and between pulses. In the paper the design of the detection system is presented, together with the experimental results on prototypes. 4 refs., 3 figs., 1 tab

Risks Associated with Shutdown in PWRs

International Nuclear Information System (INIS)

Grlicarev, I.

1996-01-01

The selected set of risks associated with reactor shutdown in PWRs are outlined and discussed (e. g. outage planning, residual heat removal capability, rapid boron dilution, containment integrity, fire protection). The contribution of different outage strategies to overall core damage risk during shutdown is assessed for a particular basic outage plan. The factors which increase or minimize the probability of reactor coolant boiling or core damage are analysed. (author)

COMPUTING SERVICES DURING THE ANNUAL CERN SHUTDOWN

CERN Multimedia

2001-01-01

As in previous years, computing services run by IT division will be left running unattended during the annual shutdown. The following points should be noted. No interruptions are scheduled for local and wide area networking and the ACB, e-mail and unix interactive services. Unix batch services will be available but without access to manually mounted tapes. Dedicated Engineering services, general purpose database services and the Helpdesk will be closed during this period. An operator service will be maintained and can be reached at extension 75011 or by Email to computer.operations@cern.ch. Users should be aware that, except where there are special arrangements, any major problems that develop during this period will most likely be resolved only after CERN has reopened. In particular, we cannot guarantee backups for Home Directory files (for Unix or Windows) or for email folders. Any changes that you make to your files during this period may be lost in the event of a disk failure. Please note that all t...

JIT single machine scheduling problem with periodic preventive maintenance

Science.gov (United States)

Shahriari, Mohammadreza; Shoja, Naghi; Zade, Amir Ebrahimi; Barak, Sasan; Sharifi, Mani

2016-09-01

This article investigates a JIT single machine scheduling problem with a periodic preventive maintenance. Also to maintain the quality of the products, there is a limitation on the maximum number of allowable jobs in each period. The proposed bi-objective mixed integer model minimizes total earliness-tardiness and makespan simultaneously. Due to the computational complexity of the problem, multi-objective particle swarm optimization (MOPSO) algorithm is implemented. Also, as well as MOPSO, two other optimization algorithms are used for comparing the results. Eventually, Taguchi method with metrics analysis is presented to tune the algorithms' parameters and a multiple criterion decision making technique based on the technique for order of preference by similarity to ideal solution is applied to choose the best algorithm. Comparison results confirmed the supremacy of MOPSO to the other algorithms.

Experience with after-shutdown decay heat removal - BWRs and PWRs

International Nuclear Information System (INIS)

Haugh, J.J.; Mollerus, F.J.; Booth, H.R.

1992-01-01

Boiling-water reactors (BWRs) and pressurized-water reactors (PWRs) make use of residual heat removal systems (RHRSs) during reactor shutdown. RHRS operational events involving an actual loss or significant degradation of an RHRS during shutdown heat removal are often prompted or aggravated by complex, changing plant conditions and by concurrent maintenance operations. Events involving loss of coolant inventory, loss of decay heat removal capability, or inadvertent pressurization while in cold shutdown have occurred. Because fewer automatic protective fetures are operative during cold shutdowns, both prevention and termination of events depend heavily on operator action. The preservation of RHRS cooling should be an important priority in all shutdown operations, particularly where there is substantial decay heat and a reduced water inventory. 13 refs., 3 figs., 4 tabs

Preliminary Evaluation of Removing Used Nuclear Fuel From Nine Shutdown Sites

Energy Technology Data Exchange (ETDEWEB)

Maheras, Steven J.; Best, Ralph; Ross, Steven B.; Buxton, Kenneth A.; England, Jeffery L.; McConnell, Paul

2013-04-30

The Blue Ribbon Commission on America’s Nuclear Future identified removal of stranded used nuclear fuel at shutdown sites as a priority so that these sites may be completely decommissioned and put to other beneficial uses. In this report, a preliminary evaluation of removing used nuclear fuel from nine shutdown sites was conducted. The shutdown sites included Maine Yankee, Yankee Rowe, Connecticut Yankee, Humboldt Bay, Big Rock Point, Rancho Seco, Trojan, La Crosse, and Zion. At these sites a total of 7649 used nuclear fuel assemblies and a total of 2813.2 metric tons heavy metal (MTHM) of used nuclear fuel are contained in 248 storage canisters. In addition, 11 canisters containing greater-than-Class C (GTCC) low-level radioactive waste are stored at these sites. The evaluation was divided in four components: • characterization of the used nuclear fuel and GTCC low-level radioactive waste inventory at the shutdown sites • an evaluation of the onsite transportation conditions at the shutdown sites • an evaluation of the near-site transportation infrastructure and experience relevant to the shipping of transportation casks containing used nuclear fuel from the shutdown sites • an evaluation of the actions necessary to prepare for and remove used nuclear fuel and GTCC low-level radioactive waste from the shutdown sites. Using these evaluations the authors developed time sequences of activities and time durations for removing the used nuclear fuel and GTCC low-level radioactive waste from a single shutdown site, from three shutdown sites located close to each other, and from all nine shutdown sites.

Safety analysis of Ignalina NPP during shutdown conditions

International Nuclear Information System (INIS)

Kaliatka, A.; Uspuras, E.

2000-01-01

The accident analysis for the Ignalina NPP with RBMK-1500 reactors at normal operating conditions and at minimum controlled power level (during startup of the reactor) has been performed in the frame of the project I n-Depth Safety Assessment of the Ignalina NPP , which was completed in 1996. However, the plant conditions during the reactor shutdown differ from conditions during reactor operation at full power (equipment status in protection systems, set points for actuation of safety and protection systems, etc.). Results of RELAP5 simulation of two worst initiating events during reactor shutdown - Pressure Header rupture in case of steam reactor cooldown as well as Pressure Header rupture in case of water reactor cooldown are discussed in the paper. Results of analysis shown that reactor are reliably cooled in both cases. Further analysis for all range of initial events during reactor shutdown and at shutdown conditions is recommended. (author)

Evolution of shutdown mechanism for PHWRs

International Nuclear Information System (INIS)

Singh, Manjit; Govindarajan, G.

1997-01-01

In 500 MWe PHWR, there are two independent fast acting shutdown systems namely (1) mechanical shut-off rod system and (2) liquid poison injection system. Both systems are independently capable of keeping the reactor in sub-critical condition during long shutdown. Mechanical shut-off rod system being primary shutdown system calls for a very high reliability of operation as well as effectiveness, which are mainly governed by its ability to operate within a very short time and the magnitude of negative reactivity worth it can provide. Mechanical shut-off rods are normally parked above the core by shut-off rod drive mechanism. On receiving a scram signal, shut-off rods are released from the holding electromagnetic clutch and fall under gravity into the core. This paper discusses the salient features of mechanical shut-off rod system. A brief account of detailed design and development of sub-assemblies of shut-off rod drive mechanism is also presented. (author)

A Fast Shutdown Technique for Large Tokamaks

International Nuclear Information System (INIS)

Fredrickson, E.; Schmidt, G.L.; Hill, K.; Jardin, S.C.

1999-01-01

A practical method is proposed for the fast shutdown of a large ignited tokamak. The method consists of injecting a rapid series of 30-50 deuterium pellets doped with a small ( 0.0005%) concentration of Krypton impurity, and simultaneously ramping the plasma current and shaping fields down over a period of several seconds using the poloidal field system. Detailed modeling with the Tokamak Simulation Code using a newly developed pellet mass deposition model shows that this method should terminate the discharge in a controlled and stable way without producing significant numbers of runaway electrons. A partial prototyping of this technique was accomplished in TFTR

CANDU 6 liquid injection shutdown system waterhammer analysis using PTRAN

International Nuclear Information System (INIS)

Ko, Deuk Yoon; Kim, Eun Ki; Ko, Yong Sang; Park, Byung Ho; Kim, Seok Bum

1996-06-01

An in-core LOCA could result in flooding of the helium header in the liquid injection shutdown system. Flooding of the helium header will result in severe pressure transients (waterhammer) in the liquid injection shutdown system when the shutdown signal is initiated. To evaluate the impact of the dynamic effects of this event, a pressure transient analysis has been performed. This analysis is performed using PTRAN, which is a computer program based on the method of characteristics. The results of this analysis are used in the stress analysis of the piping and pipe supports to ensure that the liquid injection shutdown system can withstand the pressure transient loadings. This analysis report documents the results of waterhammer analysis performed for the liquid injection shutdown system for the Wolsung nuclear power plant unit 2, 3 and 4. 4 tabs., 11 figs., 15 refs. (Author)

CANDU 6 liquid injection shutdown system waterhammer analysis using PTRAN

Energy Technology Data Exchange (ETDEWEB)

Ko, Deuk Yoon; Kim, Eun Ki; Ko, Yong Sang; Park, Byung Ho; Kim, Seok Bum [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1996-06-01

An in-core LOCA could result in flooding of the helium header in the liquid injection shutdown system. Flooding of the helium header will result in severe pressure transients (waterhammer) in the liquid injection shutdown system when the shutdown signal is initiated. To evaluate the impact of the dynamic effects of this event, a pressure transient analysis has been performed. This analysis is performed using PTRAN, which is a computer program based on the method of characteristics. The results of this analysis are used in the stress analysis of the piping and pipe supports to ensure that the liquid injection shutdown system can withstand the pressure transient loadings. This analysis report documents the results of waterhammer analysis performed for the liquid injection shutdown system for the Wolsung nuclear power plant unit 2, 3 and 4. 4 tabs., 11 figs., 15 refs. (Author).

Study on secondary shutdown systems in Tehran research reactor

Energy Technology Data Exchange (ETDEWEB)

Jalali, H.R.; Fadaei, A.H., E-mail: Fadaei_amir@aut.ac.ir; Gharib, M.

2015-09-15

Highlights: • A study was undertaken to summarize the techniques for secondary shutdown systems (SSS). • Neutronic calculation performed for proposed systems as SSS. • Dumping the heavy water stored in the reflector vessel is capable to shut down reactor. • Neutronic and transient calculation was done for validating the selected SSS. • All calculation shown that this system has advantages in safety and neutron economy. - Abstract: One important safety aspect of any research reactor is the ability to shut down the reactor. Usually, research reactors, currently in operation, have a single shutdown system based on the simultaneous insertion of the all control rods into the reactor core through gravity. Nevertheless, the International Atomic Energy Agency currently recommends use of two shutdown systems which are fully independent from each other to guarantee secure shutdown when one of them fails. This work presents an investigative study into secondary shutdown systems, which will be an important safety component in the research reactor and will provide another alternative way to shut down the reactor emergently. As part of this project, a study was undertaken to summarize the techniques that are currently used at world-wide research reactors for recognizing available techniques to consider in research reactors. Removal of the reflector, removal of the fuels, change in critical shape of reactor core and insertion of neutron absorber between the core and reflector are selected as possible techniques in mentioned function. In the next step, a comparison is performed for these methods from neutronic aspects. Then, chosen method is studied from the transient behavior point of view. Tehran research reactor which is a 5 MW open-pool reactor selected as a case study and all calculations are carried out for it. It has 5 control rods which serve the purpose of both reactivity control and shutdown of reactor under abnormal condition. Results indicated that heavy

Criteria for remote shutdown for light water reactors

International Nuclear Information System (INIS)

Anon.

1983-01-01

This Standard provides design criteria which require that: (1) specific controls and monitoring equipment shall be provided for achieving and maintaining the plant in a safe shutdown condition; (2) these controls be installed at a location (or locations) that is physically remote from the control room and cable spreading areas; (3) simultaneous control from both locations shall be prevented by administrative controls or devices for transfer of control from the control room to the remote location(s); and (4) the remote controls be used as defense-in-depth measure in addition to the control room shutdown controls and as a minimum shall provide for one complete channel of shutdown equipment

CAREM-25 Reactor Second Shutdown System Consolidation Analysis

International Nuclear Information System (INIS)

Gimenez, Marcelo; Zanocco, Pablo; Schlamp, Miguel

2000-01-01

CAREM Reactor Second Shutdown System (SSS) injects boron into the primary circuit in case of First Shutdown System failure in order to stop the nuclear reaction and to maintain the core in a safe condition during cold shutdown.It also has another safety function which is to inject water in the primary system at any pressure in case of LOCA.Different system requirements are analyzed during a SSS spurious trip and LOCA's transients.Two different alternatives are presented for the stand by condition pressurized system, they are solid mode and hot water layer. Both cases fulfill the design requirements from the safety point of view

Certificate for Safe Emergency Shutdown of Wind Turbines

DEFF Research Database (Denmark)

Wisniewski, Rafal; Svenstrup, Mikael; Pedersen, Andreas Søndergaard

2013-01-01

To avoid damage to a wind turbine in the case of a fault or a large wind gust, a detection scheme for emergency shutdown is developed. Specifically, the concept of a safety envelope is introduced. Within the safety envelope, the system can be shutdown without risking structural damage to the turb...

QPS/LHC Activities requiring important Tunnel Work During a future long Shutdown

CERN Document Server

Dahlerup-Petersen, K

2011-01-01

The MPE/circuit protection section is presently establishing a road map for its future LHC activities. The tasks comprise essential consolidation work, compulsory upgrades and extensions of existing machine facilities. The results of a first round of engineering exertion were presented and evaluated at a MPE activity review in December 2010. The technical and financial aspects of this program will be detailed in the ‘QPS Medium and Long-Term Improvement Plan’, to be published shortly. The QPS activities in the LHC tunnel during a future, long shutdown are closely related to this improvement chart. A project-package based program for the interventions has been established and will be presented in this report, together with estimates for the associated human and financial resources necessary for its implementation.

Safety aspects of unplanned shutdowns and trips

International Nuclear Information System (INIS)

1986-05-01

The issue of unplanned shutdowns and trips is receiving increased attention worldwide in view of its importance to plant safety and availability. There exists significant variation in the number of forced shutdowns for nuclear power plants of the same type operating worldwide. The reduction of the frequency of these events will have safety benefits in terms of reducing the frequency of plant transients and the challenges to the safety systems, and the risks of possible incidents. This report provides an insight into the causes of unplanned shutdowns experienced in operating nuclear power plants worldwide, the good practices that have been found effective in minimizing their occurrence, and the measures that have been taken to reduce these events. Specific information on the experiences, approaches and practices of some countries in dealing with this issue is presented in Appendix A

Reliability Centered Maintenance (RCM) Methodology and Application to the Shutdown Cooling System for APR-1400 Reactors

Energy Technology Data Exchange (ETDEWEB)

Faragalla, Mohamed M.; Emmanuel, Efenji; Alhammadi, Ibrahim; Awwal, Arigi M.; Lee, Yong Kwan [KEPCO International Nuclear Graduate School, Ulsan (Korea, Republic of)

2016-10-15

Shutdown Cooling System (SCS) is a safety-related system that is used in conjunction with the Main Steam and Main or Auxiliary Feedwater Systems to reduce the temperature of the Reactor Coolant System (RCS) in post shutdown periods from the hot shutdown operating temperature to the refueling temperature. In this paper RCM methodology is applied to (SCS). RCM analysis is performed based on evaluation of Failure Modes Effects and Criticality Analysis (FME and CA) on the component, system and plant. The Logic Tree Analysis (LTA) is used to determine the optimum maintenance tasks. The main objectives of RCM is the safety, preserve the System function, the cost-effective maintenance of the plant components and increase the reliability and availability value. The RCM methodology is useful for improving the equipment reliability by strengthening the management of equipment condition, and leads to a significant decrease in the number of periodical maintenance, extended maintenance cycle, longer useful life of equipment, and decrease in overall maintenance cost. It also focuses on the safety of the system by assigning criticality index to the various components and further selecting maintenance activities based on the risk of failure involved. Therefore, it can be said that RCM introduces a maintenance plan designed for maximum safety in an economical manner and making the system more reliable. For the SCP, increasing the number of condition monitoring tasks will improve the availability of the SCP. It is recommended to reduce the number of periodic maintenance activities.

Perspectives on Low Power and Shutdown Risk

International Nuclear Information System (INIS)

Camp, Allen L.; Whitehead, Donnie W.; Wheeler, Timothy A.; Lehner, John; Chu, Tsong-Lun; Lois, Erasmai; Drouin, Mary

2000-01-01

This paper presents results from a program sponsored by the US Nuclear Regulatory Commission to examine the risks from low power and shutdown operations. Significant progress has been made by the industry in reducing such risks; however, important operational events continue to occur. Current perceptions of low power and shutdown risks are discussed in the paper along with an assessment of the current methods for understanding important events and quantifying their associated risk

Italy: Analysis of Solutions for Passively Actuated Safety Shutdown Devices

International Nuclear Information System (INIS)

Burgazzi, L.

2015-01-01

This article looks at different special shutdown systems specifically engineered for prevention of severe accidents, to be implemented on Fast Reactors, with main focus on the investigation of the performance of the self-actuated shutdown systems in Sodium Fast Reactors. The passive shut-down systems are designed to shut-down system only by inherent passive reactivity feedback mechanism, under unprotected accident conditions, implying failure of reactor protection system. They are conceived to be self-actuated without any signal elaboration, since the actuation of the system is triggered by the effects induced by the transient like material dilatation, in case of overheating of the coolant for instance, according to Fast Reactor design to meet the safety requirements

Using dew points to estimate savings during a planned cooling shutdown

Science.gov (United States)

Friedlein, Matthew T.; Changnon, David; Musselman, Eric; Zielinski, Jeff

2005-12-01

In an effort to save money during the summer of 2003, Northern Illinois University (NIU) administrators instituted a four-day working week and stopped air conditioning buildings for the three-day weekends (Friday through Sunday). Shutting down the air conditioning systems caused a noticeable drop in electricity usage for that part of the campus that features in our study, with estimated total electricity savings of 1,268,492 kilowatt-hours or 17% of the average usage during that eight-week period. NIU's air conditioning systems, which relied on evaporative cooling to function, were sensitive to dew point levels. Greatest savings during the shutdown period occurred on days with higher dew points. An examination of the regional dew point climatology (1959 2003) indicated that the average summer daily dew point for 2003 was 14.9°C (58.8°F), which fell in the lowest 20% of the distribution. Based on the relationship between daily average dew points and electrical usage, a predictive model that could estimate electrical daily savings was created. This model suggests that electrical savings related to any future three-day shutdowns over summer could be much greater in more humid summers. Studies like this demonstrate the potential value of applying climatological information and of integrating this information into practical decision-making.

Reactor Shutdown Mechanism by Top-mounted Hydraulic System

Energy Technology Data Exchange (ETDEWEB)

Kim, Sang Haun; Cho, Yeong Garp; Choi, Myoung Hwan; Lee, Jin Haeng; Huh, Hyung; Kim, Jong In [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2012-05-15

There are two types of reactor shutdown mechanisms in HANARO. One is the mechanism driven by a hydraulic system, and the other is driven by a stepping motor. In HANARO, there are four Control Rod Drive Mechanisms (CRDMs) with an individual step motor and four Shutoff (SO) Units with an individual hydraulic system located at the top of reactor pool. The absorber rods in SO units are poised at the top of the core by the hydraulic force during normal operation. The rods of SO units drop by gravity as the first reactor showdown mechanism when a trip is commended by the reactor protection system (RPS). The rods in CRDMs also drop by gravity together as a redundant shutdown mechanism. When a trip is commended by the reactor regulating system (RRS), the absorber rods of CRDM only drop; while the absorber rods of SO units stay at the top of the core by the hydraulic system. The reactivity control mechanisms of in JRTR, one of the new research reactor with plate type fuels, consist of four CRDMs driven by an individual step motor and two second shutdown drive mechanisms (SSDMs) driven by an individual hydraulic system as shown in Fig. 1. The CRDMs act as the first reactor shutdown mechanism and reactor regulating as well. The top-mounted SSDM driven by the hydraulic system for the JRTR is under design in KAERI. The SSDM provides an alternate and independent means of reactor shutdown. The second shutdown rods (SSRs) of the SSDM are poised at the top of the core by the hydraulic system during the normal operation and drop by gravity for the reactor trip. Based on the proven technology of the design, operation and maintenance for HANARO, the SSDM for the JRTR has been optimized by the design improvement from the experience and test. This paper aims for the introduction of the SSDM in the process of the basic design. The major differences of the shutdown mechanisms by the hydraulic system are compared between HANARO and JRTR, and the design features, system, structure and

An attempt for economic estimate of the shutdown of uranium production

International Nuclear Information System (INIS)

Jonchev, L.

1997-01-01

Uranium ore has been obtained since the end of 30s till 1992. No measures for protection of the environment and restricting the risk for the population during the production have been taken. Among the three possible models of shutting down the most inexpedient from economic point of view has been applied . It meant that the beginning of closing down took place far behind ceasing the production itself and the expenses for restoration were as big as fourteen times more in comparison to the two ones. The investments for prospecting and preparing new resources were lost. The whole process was made extremely inefficiently and unprofessionally. Because of the sudden closing down of production activities there was no enough time for gathering, processing and analyzing of necessary data, even the radioecological and hydro-ecological evaluations were doubtfully reliable. The shutdown of uranium production as worldwide practice takes place considering ALARA (As Low As Reasonably Achievable) principle. The aim is to achieve maximum possible results by minimum investments taking into account the radioecological risk, socially accounted for and psychologically conditioned expenses. There is no statement of the radioecological risk in the preliminary evaluations of the uranium mines in Bulgaria. The investment funds for the period 1992-1996 were about 2.1 bill. leva, (equally allocated for each year) which was about 46.5 mil. US$. Because of inflation process the investments crucially decreased during the last years when most capital-intensive activities had to be carried out - the engineering shutdown and land-reclamations procedures. The biggest share of investments (about 30 mil. US$) was for environmental status maintenance, 2.5 times less (about 13 mil. US$) - for technical shutdown and only 2.1 mil. US$ - for land reclamation. The investments for the shutdown process referred to the whole production obtained were only 2.5 US$/kg U 3 O 8 while the most effective model

Optimization of reactor coolant shutdown chemistry practices for crud inventory management

International Nuclear Information System (INIS)

Fellers, B.; Barnette, J.; Stevens, J.; Perkins, D.

2002-01-01

This report describes reactor coolant shutdown chemistry control practices at Comanche Peak Steam Electric Station (CPSES, TXU-Generation, USA). The shutdown evolution is managed from a process control perspective to achieve conditions most favorable to crud decomposition and to avoiding re-precipitation of metals. The report discusses the evolution of current industry practices and the necessity for greater emphasis on shutdown chemistry control in response to Axial Offset Anomaly and growth of ex-core radiation fields during outage conditions. Nuclear Industry experience with axial offset anomaly (AOA), radiation field growth and unexpected behavior of crud during reactor shutdowns has encouraged the refinement of chemistry control practices during plant shutdown and startup. The strong implication of nickel rich crud as a cause of AOA and unexpected crud behavior has resulted in a focus on nickel inventory management. The goals for Comanche Peak Steam Electric Station (CPSES) include maintaining solubility of metals and radioisotopes, maximizing nickel removal and effective cleanup with demineralizers. This paper provides results and lessons learned from long term efforts to optimize the shutdown process. (authors)

Downstream passage and impact of turbine shutdowns on survival of silver American Eels at five hydroelectric dams on the Shenandoah River

Science.gov (United States)

Eyler, Sheila; Welsh, Stuart A.; Smith, David R.; Rockey, Mary

2016-01-01

Hydroelectric dams impact the downstream migrations of silver American Eels Anguilla rostrata via migratory delays and turbine mortality. A radiotelemetry study of American Eels was conducted to determine the impacts of five run-of-the-river hydroelectric dams located over a 195-km stretch of the Shenandoah River, Virginia–West Virginia, during fall 2007–summer 2010. Overall, 96 radio-tagged individuals (mean TL = 85.4 cm) migrated downstream past at least one dam during the study. Most American Eels passed dams relatively quickly; over half (57.9%) of the dam passage events occurred within 1 h of reaching a dam, and most (81.3%) occurred within 24 h of reaching the dam. Two-thirds of the dam passage events occurred via spill, and the remaining passage events were through turbines. Migratory delays at dams were shorter and American Eels were more likely to pass via spill over the dam during periods of high river discharge than during low river discharge. The extent of delay in migration did not differ between the passage routes (spill versus turbine). Twenty-eight American Eels suffered turbine-related mortality, which occurred at all five dams. Mortality rates for eels passing through turbines ranged from 15.8% to 40.7% at individual dams. Overall project-specific mortality rates (with all passage routes combined) ranged from 3.0% to 14.3%. To protect downstream-migrating American Eels, nighttime turbine shutdowns (1800–0600 hours) were implemented during September 15–December 15. Fifty percent of all downstream passage events in the study occurred during the turbine shutdown period. Implementation of the seasonal turbine shutdown period reduced cumulative mortality from 63.3% to 37.3% for American Eels passing all five dams. Modifying the turbine shutdown period to encompass more dates in the spring and linking the shutdowns to environmental conditions could provide greater protection to downstream-migrating American Eels.

Startup, Shutdown, & Malfunction (SSM) Emissions

Science.gov (United States)

EPA issued a final action to ensure states have plans in place that are fully consistent with the Clean Air Act and recent court decisions concerning startup, shutdown and malfunction (SSM) operations.

COMPUTING SERVICES DURING THE ANNUAL CERN SHUTDOWN

CERN Multimedia

2000-01-01

As in previous years, computing services run by IT division will be left running unattended during the annual shutdown. The following points should be noted. No interruptions are scheduled for local and wide area networking and the ACB, e-mail and unix interactive services. Maintenance work is scheduled for the NICE home directory servers and the central Web servers. Users must, therefore, expect service interruptions. Unix batch services will be available but without access to HPSS or to manually mounted tapes. Dedicated Engineering services, general purpose database services and the Helpdesk will be closed during this period. An operator service will be maintained and can be reached at extension 75011 or by email to: computer.operations@cern.ch Users should be aware that, except where there are special arrangements, any major problems that develop during this period will most likely be resolved only after CERN has reopened. In particular, we cannot guarantee backups for Home Directory files for eithe...

Stabilization and shutdown of Oak Ridge National Laboratory's Radioisotopes Production Facility

International Nuclear Information System (INIS)

Eversole, R.E.

1992-01-01

The Oak Ridge National Laboratory (ORNL) has been involved in the production and distribution of a variety of radioisotopes for medical, scientific and industrial applications since the late 1940s. Production of these materials was concentrated in a number of facilities primarily built in the 1950s and 1960s. Due to the age and deteriorating condition of these facilities, it was determined in 1989 that it would not be cost effective to upgrade these facilities to bring them into compliance with contemporary environmental, safety and health standards. The US Department of Energy (DOE) instructed ORNL to halt the production of isotopes in these facilities and maintain the facilities in safe standby condition while preparing a stabilization and shutdown plan. The goal was to place the former isotope production facilities in a radiologically and industrially safe condition to allow a 5-year deferral of the initiation of environmental restoration (ER) activities. In response to DOE's instructions, ORNL identified 17 facilities for shutdown, addressed the shutdown requirements for each facility, and prepared and implemented a three-phase, 4-year plan for shutdown of the facilities. The Isotopes Facilities Shutdown Program (IFSP) office was created to execute the stabilization and shutdown plan. The program is entering its third year in which the actual shutdown of the facilities is initiated. Accomplishments to date have included consolidation of all isotopes inventory into one facility, DOE approval of the IFSP Environmental Assessment (EA), and implementation of a detailed management plan for the shutdown of the facilities

Algorithm for determining two-periodic steady-states in AC machines directly in time domain

Directory of Open Access Journals (Sweden)

Sobczyk Tadeusz J.

2016-09-01

Full Text Available This paper describes an algorithm for finding steady states in AC machines for the cases of their two-periodic nature. The algorithm enables to specify the steady-state solution identified directly in time domain despite of the fact that two-periodic waveforms are not repeated in any finite time interval. The basis for such an algorithm is a discrete differential operator that specifies the temporary values of the derivative of the two-periodic function in the selected set of points on the basis of the values of that function in the same set of points. It allows to develop algebraic equations defining the steady state solution reached in a chosen point set for the nonlinear differential equations describing the AC machines when electrical and mechanical equations should be solved together. That set of those values allows determining the steady state solution at any time instant up to infinity. The algorithm described in this paper is competitive with respect to the one known in literature an approach based on the harmonic balance method operated in frequency domain.

Shutdown cooling temperature perturbation test for analysis of potential flow blockages

International Nuclear Information System (INIS)

Handbury, J.; Newman, C.; Shynot, T.

1996-01-01

This paper details the methods and results of the 'shutdown cooling test' in October 1995. This novel test was conducted at PLGS while the reactor was shutdown and shutdown cooling (SDC) waster was recirculating to find potential channel blockages resulting from the introduction of wood debris. This test discovered most of the channels that contained major wood and metal debris. (author)

Electricity-market price and nuclear power plant shutdown: Evidence from California

International Nuclear Information System (INIS)

Woo, C.K.; Ho, T.; Zarnikau, J.; Olson, A.; Jones, R.; Chait, M.; Horowitz, I.; Wang, J.

2014-01-01

Japan's Fukushima nuclear disaster, triggered by the March 11, 2011 earthquake, has led to calls for shutting down existing nuclear plants. To maintain resource adequacy for a grid's reliable operation, one option is to expand conventional generation, whose marginal unit is typically fueled by natural-gas. Two timely and relevant questions thus arise for a deregulated wholesale electricity market: (1) what is the likely price increase due to a nuclear plant shutdown? and (2) what can be done to mitigate the price increase? To answer these questions, we perform a regression analysis of a large sample of hourly real-time electricity-market price data from the California Independent System Operator (CAISO) for the 33-month sample period of April 2010–December 2012. Our analysis indicates that the 2013 shutdown of the state's San Onofre plant raised the CAISO real-time hourly market prices by $6/MWH to $9/MWH, and that the price increases could have been offset by a combination of demand reduction, increasing solar generation, and increasing wind generation. - Highlights: • Japan's disaster led to calls for shutting down existing nuclear plants. • We perform a regression analysis of California's real-time electricity-market prices. • We estimate that the San Onofre plant shutdown has raised the market prices by $6/MWH to $9/MWH. • The price increases could be offset by demand reduction and renewable generation increase

Supplementary control points for reactor shutdown without access to the main control room (International Electrotechnical Commission Standard Publication 965:1989)

International Nuclear Information System (INIS)

Kubalek, J.; Hajek, B.

1993-01-01

This standard establishes the requirements for supplementary Control Points provided to enable the operating staff to shut down the reactor and maintain the plant in a safe shut-down condition when the main control room is no longer available. This standard covers the functional selection, design and organization of the man/machine interface. It also establishes requirements for procedures which systematically verify and validate the functional design of supplementary control points. The requirements reflect the application of human engineering principles as they apply to man/machine interface. This standard does not cover special emergency response centres (e.g. a Technical Support Centre). It also does not include the detailed equipment design. Unavailability of the main control room controls due to intentionally man-induced events is not considered

The accidents during shutdown conditions Temelin NPP

International Nuclear Information System (INIS)

Sykora, M.; Mlady, O.

1996-01-01

Two parallel activities oriented for the accidents during shutdown conditions are performed at Temelin NPP: Development of symptom based emergency operating procedures (EOPs) applicable for the accidents which could occur during operational modes 1 through 4; independent evaluation of plant safety as part of the Temelin Shutdown probabilistic assessment to define the accidents which could occur during mode 5 and 6 for which the EOPs must be extended. Both these activities are in progress now because Temelin plant is still in the construction phase

Fluid shut-down system for a nuclear reactor

International Nuclear Information System (INIS)

Barclay, F.W.; Frey, J.R.; Wilson, J.N.; Besant, R.W.

1975-01-01

A nuclear reactor shut-down system is described which comprises a fluidic vortex valve for releasably maintaining a liquid neutron poison outside of the reactor core, the poison being contained by a reservoir and biased by pressure for flow into poison tubes within the reactor. The upper ends of the poison tubes communicate with the supply port of the vortex valve. A continuous gas flow into the control port maintains normal controlled operation. Shut-down is effected by interruption of the control input. One embodiment comprises three groups of poison tubes and one vortex valve associated with each group wherein shut-down is effected by poison release in two out of the three groups. Preferably, each vortex valve comprises three control ports which operate on a ''voting'' or two-out-of-three basis. (Official Gazette)

The CANDU man-machine interface and simulator training

International Nuclear Information System (INIS)

Hinchley, E.M.; Yanofsky, N.

1982-09-01

The most significant features of the man-machine interface for CANDU power stations are the extensive use of computer-driven colour graphics displays and the small number of manual controls. The man-machine interface in CANDU stations is designed to present the operator with concise, easy-to-understand information. Future developments in the use of computers in safety shutdown systems, and the use of data highway technologies in plant regulating systems will present special requirements and new opportunities in the application of human factors engineering to the control room. Good man-machine interaction depends on operator training as much as on control room design. In Canada computerized training simulators, which indicate plant response to operator action, are being introducted for operator training. Such simulators support training in normal operation of all plant systems and also in the fault management tasks following malfunctions

Retrofit of AECL CAN6 seals into the Pickering shutdown cooling pumps

International Nuclear Information System (INIS)

Rhodes, D.; Metcalfe, R.; Brown, G.

1997-01-01

The existing mechanical seals in the shutdown cooling (SDC) pumps at the eight-unit Pickering Nuclear Generating Station have caused as least seven forced outages in the last fifteen years. The SDC pumps were originally intended to run only during shutdowns, mostly at low pressure, except for short periods during routine testing of SDC isolation valves while the plant is operating at full pressure to verify that the emergency core injection system is available. Unfortunately, in practice, some SDC pumps must be run much more frequently than this to prevent overheating or freezing of components in the system while the plant is at power. This more severe service has decreased seal lifetime from about 8000 running hours to about 3000 running hours. Rather than tackling the difficult task of eliminating on-power running of the pumps, Pickering decided to install a more robust seal design that could withstand this. Through the process of competitive tender, AECL's CAN6 seal was chosen. This seal has a successful history in similarly demanding conditions in boiling water reactors in the USA. To supplement this and demonstrate there would be no 'surprises,' a 2000-hour test program was conducted. Testing consisted of simulating all the expected conditions, plus some special tests under abnormal conditions. This has given assurance that the seal will operate reliably in the Pickering shutdown cooling pumps. (author)

Retrofit of AECL CAN6 seals into the Pickering shutdown cooling pumps

International Nuclear Information System (INIS)

Rhodes, D.; Metcalfe, R.; Brown, G.; Kiameh, P.; Burchett, P.

1997-01-01

The existing mechanical seals in the shutdown cooling (SDC) pumps at the eight-unit Pickering Nuclear Generating Station have caused at least seven forced outages in the last fifteen years. The SDC pumps were originally intended to run only during shutdowns, mostly at low pressure, except for short periods during routine testing of SDC isolation valves while the plant is operating at full pressure to verify that the emergency core injection system is available. Unfortunately, in practice, some SDC pumps must be run much more frequently than this to prevent overheating or freezing of components in the system while the plant is at power. This more severe service has decreased seal lifetime from about 8000 running hours to about 3000 running hours. Rather than tackling the difficult task of eliminating on-power running of the pumps, Pickering decided to install a more robust seal design that could withstand this. Through the process of competitive tender, AECL's CAN6 seal was chosen. This seal has a successful history in similarly demanding conditions in boiling water reactors in the USA. To supplement this and demonstrate there would be no 'surprises,' a 2000-hour test program was conducted. Testing consisted of simulating all the expected conditions, plus some special tests under abnormal conditions. This has given assurance that the seal will operate reliably in the Pickering shutdown cooling pumps. (author)

Reactor shutdown device

International Nuclear Information System (INIS)

Matsumiya, Hirohito; Endo, Hiroshi; Tsuboi, Yasushi.

1993-01-01

The present invention concerns a reactor shutdown device capable of suppressing change of a core insertion amount relative to temperature change during normal operation and having a great extension amount due to thermal expansion and high mechanical strength. A control rod main body is contained vertically movably in a guide tube disposed in a reactor core. An extension member extends upward from the upper end of a control rod main body and suspends the control rod main body. A shrinkable member intervenes at a midway of the extension member and is made shrinkable. A temperature sensitive member contains coolants at the inside and surrounds the shrinkable member. Thus, if the temperature of external coolants rises abruptly, the shrinkable member is extended by thermal expansion of the coolants in the temperature sensitive member. Upon usual reactor startup, the coolants in the temperature sensitive member cause no substantial thermal expansion by temperature elevation from a cold shutdown temperature to a rated power operation temperature, and the shrinkable member maintains its original state, so that the control rod main body is not inserted into the reactor core. However, upon abrupt temperature elevation, the control rod main body is inserted into the reactor core. (I.S.)

Industry shutdown rates and permanent layoffs: evidence from firm-worker matched data

Directory of Open Access Journals (Sweden)

Kim P. Huynh

2017-06-01

Full Text Available Abstract Firm shutdown creates a turbulent situation for workers as it leads directly to layoffs for its workers. An additional consideration is whether a firm’s shutdown within an industry creates turbulence for workers at other continuing firms. Using data drawn from the Longitudinal Worker File, a Canadian firm-worker matched employment database, we investigate the impact of industry shutdown rates on workers at continuing firm. This paper exploits variation in shutdown rates across industries and within an industry over time to explain the rate of permanent layoffs and the growth of workers’ earnings. We find an increase in industry shutdown rates increases the probability of permanent layoffs and decreases earnings growth for workers at continuing firms.

Startup and shutdown of the PULSAR Tokamak Reactor

International Nuclear Information System (INIS)

Werley, K.A.; Bathke, C.G.

1994-01-01

Start-up conditions are examined for a pulsed tokamak reactor that uses only inductive plasma current drive for startup, burn and shutdown. A zero-dimensional (profile-averaged) model that describes plasma power and particle balance equations is used to study several aspects of plasma startup and shutdown, including optimization of the startup pathway tradeoff of auxiliary startup heating power versus startup time, volt-second consumtion, thermal stability and partial-power operations

Dynamic analysis of the BPX machine structure

International Nuclear Information System (INIS)

Dahlgen, F.; Citrolo, J.; Knutson, D.; Kalish, M.

1992-01-01

A preliminary analysis of the response of the BPX machine structure to a seismic input was performed. MSC/NASTRAN 5 , a general purpose XXX element computer code, has been used. The purpose of this paper is to assess the probable range of seismically induced stresses and deflections in the machine substructure which connects the machine to the test cell floor, with particular emphasis on the shear pins which will be used to attach the TF coil modules to the machine substructure (for a more detailed description of the shear pins and structure see ref. 4 in these proceedings). The model was developed with sufficient detail to be used subsequently to investigate the transient response to various dynamic loading conditions imposed on the structure by the PF, TF, and Vacuum Vessel, during normal and off-normal operations. The model does not include the mass and stiffness of the building or the building-soil interaction and as such can only be considered an interim assessment of the dynamic response of the machine to the S.S.E.(this is the Safe Shutdown Earthquake which is also the Design XXX Earthquake for all major structural components)

Preliminary Evaluation of Removing Used Nuclear Fuel from Shutdown Sites

Energy Technology Data Exchange (ETDEWEB)

Maheras, Steven J.; Best, Ralph E.; Ross, Steven B.; Buxton, Kenneth A.; England, Jeffery L.; McConnell, Paul E.

2013-09-30

This report fulfills the M2 milestone M2FT-13PN0912022, “Stranded Sites De-Inventorying Report.” In January 2013, the U.S. Department of Energy (DOE) issued the Strategy for the Management and Disposal of Used Nuclear Fuel and High-Level Radioactive Waste (DOE 2013). Among the elements contained in this strategy is an initial focus on accepting used nuclear fuel from shutdown reactor sites. This focus is consistent with the recommendations of the Blue Ribbon Commission on America’s Nuclear Future, which identified removal of stranded used nuclear fuel at shutdown sites as a priority so that these sites may be completely decommissioned and put to other beneficial uses (BRC 2012). Shutdown sites are defined as those commercial nuclear power reactor sites where the nuclear power reactors have been shut down and the site has been decommissioned or is undergoing decommissioning. In this report, a preliminary evaluation of removing used nuclear fuel from 12 shutdown sites was conducted. The shutdown sites were Maine Yankee, Yankee Rowe, Connecticut Yankee, Humboldt Bay, Big Rock Point, Rancho Seco, Trojan, La Crosse, Zion, Crystal River, Kewaunee, and San Onofre. These sites have no other operating nuclear power reactors at their sites and have also notified the U.S. Nuclear Regulatory Commission that their reactors have permanently ceased power operations and that nuclear fuel has been permanently removed from their reactor vessels. Shutdown reactors at sites having other operating reactors are not included in this evaluation.

A Study on Fire Ignition Frequency of UCN 3 during Shutdown

International Nuclear Information System (INIS)

Kim, Kilyoo; Kang, DaeIl; Jang, Seung-Cheol

2014-01-01

A fire ignition frequency of UCN 3 during shutdown, i.e., during POS 3, 4, 5, 6 was calculated by using the new fire PSA method suggested in NUREG/CR-7114. As the fire ignition frequency during full power is calculated by the fixed ignition source and the transient ignition source, the one during shutdown is also calculated by the fixed and the transient ignition source. Since the fixed ignition source was already verified through the walkdown although the walkdown is for the fixed ignition source during full power, additional walkdown for the one during shutdown is not necessary. In the paper, how the fire ignition frequency of UCN 3 during shutdown was calculated is described. A fire ignition frequency of UCN 3 during shutdown, i.e., during POS 3, 4, 5, 6 was calculated by using the new fire PSA method suggested in NUREG/CR-7114. We make the transient ignition fire frequency of each BIN vary according to the daily work order of each POS

BWR startup and shutdown activity transport control

Energy Technology Data Exchange (ETDEWEB)

Garcia, S.E., E-mail: sgarcia@epri.com [Electric Power Research Inst. (EPRI), Palo Alto, California (United States); Giannelli, J.F.; Jarvis, A.J., E-mail: jgiannelli@finetech.com, E-mail: ajarvis@finetech.com [Finetech, Inc., Parsippany, New Jersey (United States)

2010-07-01

This paper summarizes BWR industry experience on good practices for controlling the transport of corrosion product activity during shutdowns, particularly refueling outages, and for startup chemistry control to minimize IGSCC (intergranular stress corrosion cracking). For shutdown, overall goals are to minimize adverse impacts of crud bursts and the time required to remove activated corrosion products from the reactor coolant during the shutdown process prior to refueling, and to assist plants in predicting and controlling radiation exposure during outages. For startup, the overall goals are to highlight conditions during early heatup and startup when sources of reactor coolant oxidants are high, when there is a greater likelihood for chemical excursions associated with refueling outage work activities, and when hydrogen injection is not available to mitigate IGSCC due to system design limitations. BWR water chemistry has changed significantly in recent years with the adoption of hydrogen water chemistry, zinc addition and noble metal chemical applications. These processes have, in some instances, resulted in significant activity increases during shutdown evolutions, which together with reduced time for cleanup because of shorter outages, has consequently increased outage radiation exposure. A review several recent outages shows that adverse effects from these conditions can be minimized, leading to the set of good practice recommendations for shutdown chemistry control. Most plants lose the majority of their hydrogen availability hours during early startup because feedwater hydrogen injection systems were not originally designed to inject hydrogen below 20% power. Hydrogen availability has improved through modifications to inject hydrogen at lower power levels, some near 5%. However, data indicate that IGSCC is accelerated during early startup, when dissolved oxygen and hydrogen peroxide levels are high and reactor coolant temperatures are in the 300 to 400 {sup o

WIMS-AECL/RFSP code validation of reactivity calculations following a long shutdown using the simple-cell history-based method

International Nuclear Information System (INIS)

Ardeshiri, F.; Donnelly, J.V.; Arsenault, B.

1998-01-01

The purpose of this analysis is to validate the Reactor Fuelling Simulation Program (RFSP) using the simple-cell model (SCM) history-based method in a startup simulation following a reactor shutdown period. This study is part of the validation work for history-based calculations, using the WIMS-AECL code with the ENDF/B-V library, and the SCM linked to the RFSP code. In this work, the RFSP code with the SCM history-based method was used to track a 1-year period of the Point Lepreau reactor operating history, that included a 12-day reactor shutdown and subsequent startup. Measured boron and gadolinium concentrations were used in the RFSP simulations, and the predicted values of core reactivity were compared to the reference (pre-shutdown) value. The discrepancies in core reactivity are shown to be better than ±2 milli-k at any time, and better than about ±0.5 milli-k towards the end of the startup transient. The results of this analysis also show that the calculated maximum channel and bundle powers are within an acceptable range during both the core-follow and the reactor startup simulations. (author)

Operating and maintenance experience of Dhruva secondary shutdown system

International Nuclear Information System (INIS)

Sharma, U.L.; Bharathan, R.

1997-01-01

Nine numbers of cadmium shut-off rods are used as primary fast acting shutdown devices while moderator dumping is used as secondary shutdown system. The secondary shutdown system in Dhruva reactor comprises of 3 dump valves and 3 control valves. Under normal operations, the control valves are used to control the moderator level and thereby the reactor power. Under Trip conditions the dump valves as well as the control valves open fully, dumping the moderator to the dump tank, thereby acting as secondary shutdown devices. While the failure of any of these valves to close fully is an incident, the failure of any of these valves to open on a demand is a safety related unusual occurrence and needs to be viewed seriously. During the last 11 years of operation of these valves, there was one incidence of a valve not closing fully and there were two instances of a valve not opening fully on demand. The possible causes, the corrective action taken to rehabilitate these valves and the elaborate system preparations undertaken to enable maintenance jobs are described. (author)

Shutdown chemistry optimization at Maanshan NPP

International Nuclear Information System (INIS)

Sun Yuanlung; Chuang Benjamin; Su Kouhwa; Kao Jueiting

2009-01-01

At Maanshan PWRs, a significant piping radiation buildup caused by crud burst from fuel surface in the beginning of RFO used to be blamed as a contribution to high personal exposures during outage. Therefore, several modifications on shutdown chemistry procedures such as, early lithium removal, rapid boration, dissolved hydrogen removal, extended RCP operation, and maintaining maximum let down flow, have been consecutively conducted since no.1RFO-16, 2006. The important operational and chemical parameters of modified shutdown chemistry procedures adopted in no.2 RFO-17, 2008 and superiority in low reading (2 mSv/hr) from let down heat exchangers area radiation monitor over 11mSv/hr of no.1 RFO-16 at the same area will be addressed in this paper. At the end of no.2 RFO-17, low personal exposures of 765 man-mSv (TLD)verified the absence of crud burst during shutdown chemistry process and broke records of Maanshan NPP as well. Even with a new job on PZR pre-emptive dissimilar weld overlay which exhausting 17.37% of total 797 man-mSv(TLD) in the latest no.1 RFO-18, 659 man-mSv (TLD) made another record low in the history of Maanshan. (author)

Letter report seismic shutdown system failure mode and effect analysis

International Nuclear Information System (INIS)

KECK, R.D.

1999-01-01

The Supply Ventilation System Seismic Shutdown ensures that the 234-52 building supply fans, the dry air process fans and vertical development calciner are shutdown following a seismic event. This evaluates the failure modes and determines the effects of the failure modes

Preliminary Evaluation of Removing Used Nuclear Fuel from Shutdown Sites

Energy Technology Data Exchange (ETDEWEB)

Maheras, Steven J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Best, Ralph E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Ross, Steven B. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Buxton, Kenneth A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); England, Jeffery L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); McConnell, Paul E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Massaro, Lawrence M. [Fermi Research Alliance (FRA), Batavia, IL (United States); Jensen, Philip J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2016-09-30

A preliminary evaluation of removing spent nuclear fuel (SNF) from 13 shutdown nuclear power plant sites was performed. At these shutdown sites the nuclear power reactors have been permanently shut down and the sites have been decommissioned or are undergoing decommissioning. The shutdown sites were Maine Yankee, Yankee Rowe, Connecticut Yankee, Humboldt Bay, Big Rock Point, Rancho Seco, Trojan, La Crosse, Zion, Crystal River, Kewaunee, San Onofre, and Vermont Yankee. The evaluation was divided into four components: Characterization of the SNF and greater-than-Class C low-level radioactive waste (GTCC waste) inventory A description of the on-site infrastructure at the shutdown sites An evaluation of the near-site transportation infrastructure and transportation experience at the shutdown sites An evaluation of the actions necessary to prepare for and remove SNF and GTCC waste. The primary sources for the inventory of SNF and GTCC waste were the U.S. Department of Energy (DOE) spent nuclear fuel inventory database, industry publications such as StoreFUEL, and government sources such as the U.S. Nuclear Regulatory Commission. The primary sources for information on the conditions of on-site infrastructure and near-site transportation infrastructure and experience included information collected during site visits, information provided by managers at the shutdown sites, Facility Interface Data Sheets compiled for DOE in 2005, Services Planning Documents prepared for DOE in 1993 and 1994, industry publications such as Radwaste Solutions, and Google Earth. State staff, State Regional Group representatives, a Tribal representative, and a Federal Railroad Administration representative have participated in nine of the shutdown site visits. Every shutdown site was found to have at least one off-site transportation mode option for removing its SNF and GTCC waste; some have multiple options. Experience removing large components during reactor decommissioning provided an

Inspection maintenance and planning of shutdown in thermal electric generating plants

International Nuclear Information System (INIS)

Dezordi, W.L.; Correa, D.A.; Kina, M.

1984-01-01

The schedule shutdown of an industrial plant and, more specifically, of an electrical generating station, is becoming increasingly important. The major parameters to be taken into account for the planning of such a shutdown are basically of economic-financial nature such as costs of the related services (materials, equipment, manpower, etc), loss of revenue caused by the station's shutdown as well as by the station availability, and other requirements expected from it by the Load Dispatch and consumers. Improving the equipment's performances and the station's availability are the fundamental objectives to be strived for. The authors present in this paper, in an abridged form, the planning tools used for thermal electric generating plants shutdowns for inspections, maintenance and design changes implementation. (Author) [pt

77 FR 75198 - Standard Format and Content for Post-Shutdown Decommissioning Activities Report

Science.gov (United States)

2012-12-19

... NUCLEAR REGULATORY COMMISSION [NRC-2012-0299] Standard Format and Content for Post-Shutdown... regulatory guide (DG), DG-1272, ``Standard Format and Content for Post-shutdown Decommissioning Activities... Content for Post-shutdown Decommissioning Activities Report,'' which was issued in July 2000. DG-1271...

40 CFR 63.310 - Requirements for startups, shutdowns, and malfunctions.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 9 2010-07-01 2010-07-01 false Requirements for startups, shutdowns, and malfunctions. 63.310 Section 63.310 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... CATEGORIES National Emission Standards for Coke Oven Batteries § 63.310 Requirements for startups, shutdowns...

76 FR 81998 - Methodology for Low Power/Shutdown Fire PRA

Science.gov (United States)

2011-12-29

... NUCLEAR REGULATORY COMMISSION [NRC-2011-0295] Methodology for Low Power/Shutdown Fire PRA AGENCY..., ``Methodology for Low Power/Shutdown Fire PRA--Draft Report for Comment.'' DATES: Submit comments by March 01... risk assessment (PRA) method for quantitatively analyzing fire risk in commercial nuclear power plants...

Shutdowns/scrams at BWRs reported under new 1984 LER rule

International Nuclear Information System (INIS)

Mays, G.T.

1985-01-01

Operating experience data from nuclear power plants are essential for safety and reliability analyses. The Licensee Event Reports (LERs), submitted to the NRC by nuclear power plant utilities, contain much of this data. One of the significant aspects of the new LER rule includes the requirement to report all plant shutdowns whereas prior to 1984, not all shutdowns were reported as LERs. This paper reviews the shutdowns and scrams occurring during the first six months of 1984 at BWRs as reported under the new LER rule. The review focused on systems involved, causes, and personnel interactions

Alternative Shutdown Panel. Amaraz Nuclear Power Plant

Energy Technology Data Exchange (ETDEWEB)

Saenz de Santa Maria Valin, J.

2016-07-01

Between 2010 and 2014 the Nuclear Power Plant of Almaraz conducted one of the most complex projects in its history: The installation of an Alternative Shutdown Panel with the capability to stop the plant in case of fire in the Control room or in the Cable room. This project represented a great economic and organizational effort for the plant, but at the same time has been a great improvement in the safety of the installation, which was demonstrated by the achievement of a major milestone in the history of Almaraz: The actual shutdown from outside of the Control room. (Author)

Training simulator for advanced gas-cooled reactor (AGR) shutdown sequence equipment

International Nuclear Information System (INIS)

Shankland, J.P.; Nixon, G.L.

1978-01-01

Successful shutdown of nuclear plant is of prime importance for both safety and economic reasons and large sums of money are spent on equipment to make shutdowns fully automatic, thus removing the possibility of operator errors. While this aim can largely be realized, one must consider the possibility of automatic equipment or plant failures when operators are required to take manual action, and off-line training facilities should be available to operating staff to minimize the risk of incorrect actions being taken. This paper presents the practice adopted at Hunterston 'B' Nuclear Power Station to solve this problem and concerns the computer-based training simulator for the Reactor Shutdown Sequence Equipment (RSSE) which was commissioned in January 1977. The plant associated with shutdown is briefly described and the reasoning which shows the need for a simulator is outlined. The paper also gives details of the comprehensive facilities available on the simulator and goes on to describe the form that shutdown training takes and the experience gained at this time. (author)

77 FR 10576 - Methodology for Low Power/Shutdown Fire PRA

Science.gov (United States)

2012-02-22

... NUCLEAR REGULATORY COMMISSION [NRC-2011-0295] Methodology for Low Power/Shutdown Fire PRA AGENCY.../Shutdown Fire PRA.'' In response to request from members of the public, the NRC is extending the public... risk assessment (PRA) method for quantitatively analyzing fire risk in commercial nuclear power plants...

Development of self-actuated shutdown system using curie point electromagnet

International Nuclear Information System (INIS)

Kim, Tae Ryong; Park, Jin Ho

1999-01-01

An innovative concept for a passive reactor shutdown system, so called self-actuated shutdown system (SASS), is inevitably required for the inherent safety in liquid metal reactor, which is designed with the totally different concept from the usual reactor shutdown system in LWR. SASS using Curie point electromagnet (CPEM) was selected as the passive reactor shutdown system for KALIMER (Korea Advanced Liquid Metal Reactor). A mock-up of the SASS was designed, fabricated and tested. From the test it was confirmed that the mockup was self-actuated at the Curie point of the temperature sensing material used in the mockup. An articulated control rod was also fabricated and assembled with the CPEM to confirm that the control rod can be inserted into core even when the control rod guide tube is deformed due to earthquake. The operability of SASS in the actual sodium environment should be confirmed in the future. All the design and test data will be applied to the KALIMER design. (author)

Design of shutdown system no.2 liquid poison injection system for 500 MWe PHWR

International Nuclear Information System (INIS)

Bhatnagar, S.; Balasubrahmanian, A.K.; Pillai, A.V.

1997-01-01

Defence in depth and two group system concepts form the basic design philosophy for the shutdown systems. There are two independent, diverse and fast acting shutdown systems provided for the 500 MWe PHWR. The design is based on fail-safe principle, sufficient component redundancy and on-line testing. Liquid poison injection system, as shutdown system 2, is newly developed for the 500 MWe PHWRs. The system operates by rapidly injecting gadolinium nitrate solution into bulk moderator using stored helium pressure thereby inserting negative reactivity. A high pressure helium supply tank which provides the energy for system actuation, is connected, through an array of fast acting valves in series-parallel arrangement, to the individual poison tanks storing gadolinium nitrate solution. The valves, belonging to three different channels of reactor Protection System 2, are the only active components in the system. The valves are fail safe and are periodically tested on-line without actually firing the system. The system comprising of in-core assemblies and the external process system has been engineered. Experimental work is being carried out by BARC for design validation and data generation. This paper describes the conceptual development, design basis, design parameters and detailed engineering of the system. (author)

30 CFR 57.8534 - Shutdown or failure of auxiliary fans.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Shutdown or failure of auxiliary fans. 57.8534... Ventilation Underground Only § 57.8534 Shutdown or failure of auxiliary fans. (a) Auxiliary fans installed and... fan maintenance or fan adjustments where air quality is maintained in compliance with the applicable...

PSA for the shutdown mode for nuclear power plants

International Nuclear Information System (INIS)

1994-06-01

The meeting, which was attended by more than 75 participants from 20 countries, provided a broad discussion forum where all the currently active major shutdown PSA programmes were reviewed. The meeting also addressed the issues related to actual performance of shutdown PSA studies as well as insight gained from the studies. This document, which was prepared during the TCM, contains the results of extensive discussions which were held in specific working groups. The papers presented at the meeting provide a comprehensive overview of the state of the art of shutdown risk assessment and remedial measures taken to reduce the risk in outages. It is hoped that this document will be very useful to all individuals with interest in increasing safety during outages at NPPs. Refs, figs and tabs

Core shutdown report: Subcycle K-14.1

International Nuclear Information System (INIS)

Gough, S.T.

1992-05-01

When a reactor is shut down, there is a set of rules that must be followed to guarantee that the reactor remains in a safe shutdown state. Some of these rules involve the cooling of heat generating assemblies before, during, and after charge-discharge (C ampersand D) operations. These rules ensure that C ampersand D operations will not endanger the integrity of the fuel or targets by allowing them to overheat. DPSOL 105-1225, Assembly Discharge and Forced Cooling Requirements, is the primary operations procedure that governs these cooling rules. The specific shutdown cooling limits that are input into this procedure are contained within this report

Failure and Reliability Analysis for the Master Pump Shutdown System

International Nuclear Information System (INIS)

BEVINS, R.R.

2000-01-01

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

Optimization of startup and shutdown operation of simulated moving bed chromatographic processes.

Science.gov (United States)

Li, Suzhou; Kawajiri, Yoshiaki; Raisch, Jörg; Seidel-Morgenstern, Andreas

2011-06-24

This paper presents new multistage optimal startup and shutdown strategies for simulated moving bed (SMB) chromatographic processes. The proposed concept allows to adjust transient operating conditions stage-wise, and provides capability to improve transient performance and to fulfill product quality specifications simultaneously. A specially tailored decomposition algorithm is developed to ensure computational tractability of the resulting dynamic optimization problems. By examining the transient operation of a literature separation example characterized by nonlinear competitive isotherm, the feasibility of the solution approach is demonstrated, and the performance of the conventional and multistage optimal transient regimes is evaluated systematically. The quantitative results clearly show that the optimal operating policies not only allow to significantly reduce both duration of the transient phase and desorbent consumption, but also enable on-spec production even during startup and shutdown periods. With the aid of the developed transient procedures, short-term separation campaigns with small batch sizes can be performed more flexibly and efficiently by SMB chromatography. Copyright © 2011 Elsevier B.V. All rights reserved.

Management of refuelling, modifications and accidental shut-down of nuclear power plant

International Nuclear Information System (INIS)

1996-01-01

This document is the appendix of HAF 0300 (91) 'Code on the Safety of Nuclear Power Plant Operation', which was promulgated by the National Nuclear Safety Administration (NNSA) on March 2, 1994, and has the same legal effect. This appendix is applicable to establish the administrative management procedures for refuelling, modifications and accidental shut-down in the period of operation of pressurized water thermal neutron reactor of nuclear power plants. The NNSA shall be responsible for interpretation of this document

The Alternative Design Features for Safety Enhancement in Shutdown Operation

International Nuclear Information System (INIS)

Oh, Hae Cheol; Kim, Myung Ki; Chung, Bag Soon; Seo, Mi Ro

2009-01-01

PSA can be used to confirm that the new plant design is complied with the applicable safety goals, and to select among the alternate design options. A shutdown PSA provides insight for outage planning schedule, outage management practices, and design modifications. Considering the results of both LPSD PSA studies and operating experiences for low power and shutdown, the improvements can be proposed to reduce the high risk contribution. The improvements/enhancements during shutdown operation may be divided into categories such as hardware, administrative management, and operational procedure. This paper presents on an example how the risk related to an accidental situation can be reduced, focusing the hardware design changes for the newly designed NPPs

Evaluation of slow shutdown system flux detectors in Point Lepreau Generating Station - I: dynamic response characterization

Energy Technology Data Exchange (ETDEWEB)

Anghel, V.N.P. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada); Comeau, D. [New Brunswick Power Nuclear, Point Lepreau, New Brunswick (Canada); McKay, J.; Sur, B. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada); Taylor, D. [New Brunswick Power Nuclear, Point Lepreau, New Brunswick (Canada)

2009-07-01

CANDU reactors are protected against reactor overpower by two independent shutdown systems: Shut Down System 1 and 2 (SDS1 and SDS2). At the Point Lepreau Generating Station (PLGS), the shutdown systems can be actuated by measurements of the neutron flux by Platinum-clad Inconel In-Core Flux Detectors (ICFDs). These detectors have a complex dynamic behaviour, characterized by 'prompt' and 'delayed' components with respect to immediate changes in the in-core neutron flux. The dynamic response components need to be determined accurately in order to evaluate the effectiveness of the detectors for actuating the shutdown systems. The amplitudes of the prompt and the delayed components of individual detectors were estimated over a period of several years by comparison of archived detector response data with the computed local neutron flux evolution for SDS1 and SDS2 reactor trips. This was achieved by custom-designed algorithms. The results of this analysis show that the dynamic response of the detectors changes with irradiation, with the SDS2 detectors having 'prompt' signal components that decreased significantly with irradiation. Some general conclusions about detector aging effects are also drawn. (author)

Study of methodology for low power/shutdown fire PSA

International Nuclear Information System (INIS)

Yan Zhen; Li Zhaohua; Li Lin; Song Lei

2014-01-01

As a risk assessment technology based on probability, the fire PSA is accepted abroad by nuclear industry in its application in the risk assessment for nuclear power plants. Based on the industry experience, the fire-induced impact on the plant safety during low power and shutdown operation cannot be neglected, therefore fire PSA can be used to assess the corresponding fire risk. However, there is no corresponding domestic guidance/standard as well as accepted analysis methodology up to date. Through investigating the latest evolvement on fire PSA during low power and shutdown operation, and integrating its characteristic with the corresponding engineering experience, an engineering methodology to evaluate the fire risk during low power and shutdown operation for nuclear power plant is established in this paper. In addition, an analysis demonstration as an example is given. (authors)

LS1 “First Long Shutdown of LHC and its Injector Chains”

CERN Multimedia

Foraz, K; Barberan, M; Bernardini, M; Coupard, J; Gilbert, N; Hay, D; Mataguez, S; McFarlane, D

2014-01-01

The LHC and its Injectors were stopped in February 2013, in order to maintain, consolidate and upgrade the different equipment of the accelerator chain, with the goal of achieving LHC operation at the design energy of 14 TeV in the centre-of-mass. Prior to the start of this First Long Shutdown (LS1), a major effort of preparation was performed in order to optimize the schedule and the use of resources across the different machines, with the aim of resuming LHC physics in early 2015. The rest of the CERN complex will restart beam operation in the second half of 2014. This paper presents the schedule of the LS1, describes the organizational set-up for the coordination of the works, the main activities, the different main milestones, which have been achieved so far, and the decisions taken in order to mitigate the issues encountered.

Updating of the program for simulation of Darlington shutdown and regulation systems

International Nuclear Information System (INIS)

1988-07-01

This report describes the current status of the developments of a simulation of the Darlington Nuclear Generating Station shutdown and regulating systems, DARSIM done under contract to the Atomic Energy Control Board (AECB). The DARSIM program simulates the spatial neutron dynamics, the regulation of the reactor power, and shutdown system 1 and shutdown system 2 software. The DARSIM program operates in the interactive simulation program environment. DARSIM was installed on the APOLLO computer at the AECB and a version for an IBM-PC was also provided for the exclusive use of the AECB. Shutdown system software was updated to incorporate the latest revisions in the functional specifications. Additional developments have been provided to assist in the use and interpretation of the DARSIM results

Backup passive reactivity shutdown systems

International Nuclear Information System (INIS)

Ashurko, Yu.M.; Kuznetsov, L.A.

1996-01-01

The paper reviews self-actuated shutdown systems (SASSs) for liquid metal-cooled fast reactors (LMFRs). Principles of operation are described, advantages and drawbacks analyzed, and prospects for application in advanced fast reactors examined. Ways to improve reactor self-protection via reactivity feedback amplification and related problems are discussed. (author). 9 refs, 12 figs

Backup passive reactivity shutdown systems

Energy Technology Data Exchange (ETDEWEB)

Ashurko, Yu M; Kuznetsov, L A [Institute of Physics and Power Engineering, Obninsk (Russian Federation)

1996-12-01

The paper reviews self-actuated shutdown systems (SASSs) for liquid metal-cooled fast reactors (LMFRs). Principles of operation are described, advantages and drawbacks analyzed, and prospects for application in advanced fast reactors examined. Ways to improve reactor self-protection via reactivity feedback amplification and related problems are discussed. (author). 9 refs, 12 figs.

Risk impact of BWR technical specifications requirements during shutdown

International Nuclear Information System (INIS)

Staple, B.D.; Kirk, H.K.; Yakle, J.

1994-10-01

This report presents an application of probabilistic models and risk based criteria for determining the risk impact of the Limiting Conditions of Operations (LCOs) in the Technical Specifications (TSs) of a boiling water reactor during shutdown. This analysis studied the risk impact of the current requirements of Allowed Outage Times (AOTs) and Surveillance Test Intervals (STIs) in eight Plant Operational States (POSs) which encompass power operations, shutdown, and refueling. This report also discusses insights concerning TS action statements

Loss-of-benefits analysis for nuclear power plant shutdowns: methodology and illustrative case study

International Nuclear Information System (INIS)

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

1983-11-01

A framework for loss-of-benefits analysis and a taxomony for identifying and categorizing the effects of nuclear power plant shutdowns or accidents are presented. The framework consists of three fundamental steps: (1) characterizing the shutdown; (2) identifying benefits lost as a result of the shutdown; and (3) quantifying effects. A decision analysis approach to regulatory decision making is presented that explicitly considers the loss of benefits. A case study of a hypothetical reactor shutdown illustrates one key loss of benefits: net replacement energy costs (i.e., change in production costs). Sensitivity studies investigate the responsiveness of case study results to changes in nuclear capacity factor, load growth, fuel price escalation, and discount rate. The effects of multiple reactor shutdowns on production costs are also described

Effect of dc-power-system reliability on reactor-shutdown cooling

International Nuclear Information System (INIS)

Kolaczkowski, A.M.; Baranowsky, P.W.; Hickman, J.W.

1981-01-01

The DC power systems in a nuclear power plant provide control and motive power to valves, instrumentation, emergency diesel generators, and many other components and systems during all phases of plant operation including abnormal shutdowns and accident situations. A specific area of concern is the adequacy of the minimum design requirements for DC power systems, particularly with regard to multiple and common cause failures. This concern relates to the application of the single failure criterion for assuring a reliable DC power supply which may be required for the functionability of shutdown cooling systems. The results are presented of a reliability based study performed to assess the adequacy of DC power supply design requirements for currently operating light water reactors with particular attention to shutdown cooling requirements

Post Fire Safe Shutdown Analysis Using a Fault Tree Logic Model

International Nuclear Information System (INIS)

Yim, Hyun Tae; Park, Jun Hyun

2005-01-01

Every nuclear power plant should have its own fire hazard analysis including the fire safe shutdown analysis. A safe shutdown (SSD) analysis is performed to demonstrate the capability of the plant to safely shut down for a fire in any given area. The basic assumption is that there will be fire damage to all cables and equipment located within a common fire area. When evaluating the SSD capabilities of the plant, based on a review of the systems, equipment and cables within each fire area, it should be determined which shutdown paths are either unaffected or least impacted by a postulated fire within the fire area. Instead of seeking a success path for safe shutdown given all cables and equipment damaged by a fire, there can be an alternative approach to determine the SSD capability: fault tree analysis. This paper introduces the methodology for fire SSD analysis using a fault tree logic model

40 CFR 65.6 - Startup, shutdown, and malfunction plan and procedures.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 15 2010-07-01 2010-07-01 false Startup, shutdown, and malfunction... (CONTINUED) AIR PROGRAMS (CONTINUED) CONSOLIDATED FEDERAL AIR RULE General Provisions § 65.6 Startup... Group 2A or Group 2B process vents. (b) Startup, shutdown, and malfunction plan—(1) Description and...

Reliability of Offshore Wind Turbine Drivetrains based on Measured Shut-down Events

DEFF Research Database (Denmark)

Natarajan, Anand; Buhl, Thomas

2015-01-01

by initiating blade pitching to feather and also sometimes using the generator torqueas a brake mechanism. The shutdowns due to wind speed variation nearcut-out are predicted using an Inverse First Order Reliability Model(IFORM) whereby an expected annual frequency of normal shutdownsat cut-out is put forth...... normal operation and with shutdowns. The maximum coefficient of variation (CoV) due to varying wind conditions was found on the low speed shaft torsion, but the shutdowns by themselves were not seento significantly change the fatigue loads....

Francis-99: Transient CFD simulation of load changes and turbine shutdown in a model sized high-head Francis turbine

International Nuclear Information System (INIS)

Mössinger, Peter; Jester-Zürker, Roland; Jung, Alexander

2017-01-01

With increasing requirements for hydropower plant operation due to intermittent renewable energy sources like wind and solar, numerical simulations of transient operations in hydraulic turbo machines become more important. As a continuation of the work performed for the first workshop which covered three steady operating conditions, in the present paper load changes and a shutdown procedure are investigated. The findings of previous studies are used to create a 360° model and compare measurements with simulation results for the operating points part load, high load and best efficiency. A mesh motion procedure is introduced, allowing to represent moving guide vanes for load changes from best efficiency to part load and high load. Additionally an automated re-mesh procedure is added for turbine shutdown to ensure reliable mesh quality during guide vane closing. All three transient operations are compared to PIV velocity measurements in the draft tube and pressure signals in the vaneless space. Simulation results of axial velocity distributions for all three steady operation points, during both load changes and for the shutdown correlated well with the measurement. An offset at vaneless space pressure is found to be a result of guide vane corrections for the simulation to ensure similar velocity fields. Short-time Fourier transformation indicating increasing amplitudes and frequencies at speed-no load conditions. Further studies will discuss the already measured start-up procedure and investigate the necessity to consider the hydraulic system dynamics upstream of the turbine by means of a 1D3D coupling between the 3D flow field and a 1D system model. (paper)

Francis-99: Transient CFD simulation of load changes and turbine shutdown in a model sized high-head Francis turbine

Science.gov (United States)

Mössinger, Peter; Jester-Zürker, Roland; Jung, Alexander

2017-01-01

With increasing requirements for hydropower plant operation due to intermittent renewable energy sources like wind and solar, numerical simulations of transient operations in hydraulic turbo machines become more important. As a continuation of the work performed for the first workshop which covered three steady operating conditions, in the present paper load changes and a shutdown procedure are investigated. The findings of previous studies are used to create a 360° model and compare measurements with simulation results for the operating points part load, high load and best efficiency. A mesh motion procedure is introduced, allowing to represent moving guide vanes for load changes from best efficiency to part load and high load. Additionally an automated re-mesh procedure is added for turbine shutdown to ensure reliable mesh quality during guide vane closing. All three transient operations are compared to PIV velocity measurements in the draft tube and pressure signals in the vaneless space. Simulation results of axial velocity distributions for all three steady operation points, during both load changes and for the shutdown correlated well with the measurement. An offset at vaneless space pressure is found to be a result of guide vane corrections for the simulation to ensure similar velocity fields. Short-time Fourier transformation indicating increasing amplitudes and frequencies at speed-no load conditions. Further studies will discuss the already measured start-up procedure and investigate the necessity to consider the hydraulic system dynamics upstream of the turbine by means of a 1D3D coupling between the 3D flow field and a 1D system model.

Analysis of solutions for passively activated safety shutdown devices for SFR

International Nuclear Information System (INIS)

Burgazzi, Luciano

2013-01-01

Highlights: • Innovative systems for emergency shut down of fast reactors are proposed. • The concepts of inherent and passive safety are put forward. • The relative analysis in terms of safety and reliability is presented. • A comparative assessment among the concepts is performed. • Path forward is tracked. -- Abstract: In order to enhance the inherent safety of fast reactors, innovative reactivity control systems have been proposed for intrinsic ultimate shut-down instead of conventional scram rods, to cope with the potential consequences of severe unprotected transient accidents, such as an energetic core disruptive accident, as in case of sodium fast reactors. The passive shut-down systems are designed to shut-down system only by inherent passive reactivity feedback mechanism, under unprotected accident conditions, implying failure of reactor protection system. They are conceived to be self-actuated without any signal elaboration, since the actuation of the system is triggered by the effects induced by the transient like material dilatation, in case of overheating of the coolant for instance, according to fast reactor design to meet the safety requirements. This article looks at different special shutdown systems specifically engineered for prevention of severe accidents, to be implemented on fast reactors, with main focus on the investigation of the performance of the self-actuated shutdown systems in sodium fast reactors

Nuclear reactor shutdown system

International Nuclear Information System (INIS)

Mangus, J.D.; Cooper, M.H.

1982-01-01

An improved nuclear reactor shutdown system is described comprising a temperature sensitive device connected to control the electric power supply to a magnetic latch holding a body of a neutron absorbing material. The temperature sensitive device is exposed to the reactor coolant so that when the reactor coolant temperature rises above a specific level, the temperature sensitive device will cause deenergization of the magnetic latch to allow the body of neutron absorbing material to enter the reactor core. (author)

77 FR 73968 - Reconsideration of Certain New Source and Startup/Shutdown Issues: National Emission Standards...

Science.gov (United States)

2012-12-12

...; FRL-9762-1] RIN 2060-AR62 Reconsideration of Certain New Source and Startup/Shutdown Issues: National... Source and Startup/Shutdown Issues: National Emission Standards for Hazardous Air Pollutants from Coal... November 30, 2012, proposed ``Reconsideration of Certain New Source and Startup/Shutdown Issues: National...

Probabilities of inherent shutdown of unprotected events in innovative liquid metal reactors

International Nuclear Information System (INIS)

Mueller, C.J.; Wade, D.C.

1988-01-01

The uncertainty in predicting the effectiveness of inherent shutdown in innovative liquid metal cooled reactors with metallic fuel results from three broad contributing areas of uncertainty: (1) the inability to exactly predict the frequency of ATWS events with potential to challenge the safety systems and require inherent shutdown; (2) the approximation of representing all such events by a selected set of ''generic scenarios''; and (3) the inability to exactly calculate the core response to the selected generic scenarios. This paper discusses the work being done to address each of these contributing areas, identifies the design and research approaches being used at Argonne National Laboratory to reducing the key contributions to uncertainties in inherent shutdown, and presents results. The conditional probabilities (given ATWS initiation) of achieving temperatures capable of defeating inherent shutdown are shown to range from /approximately/0.1% to negligible for current designs

SEPRA - shutdown PSA for the OLKILUOTO nuclear power plant

International Nuclear Information System (INIS)

Himanen, R.

1995-01-01

The utility TVO has extended the PSA study to the analysis of refueling, shutdown and startup. The Shutdown Event PRA (SEPRA) was reported to the authority in September 1992. The study consists of the analysis of leaks and loss of decay heat removal in the planned shutdown conditions. Special studies were performed for the cold pressurization, for local criticality events, for heavy load transport and for the transients during startup and shutdown. A remarkable effort was put to identify risks, i.e. to the qualitative analysis. The regular preventive maintenance tasks in the refueling outages were analyzed and the important tasks were selected for further studies. Besides the severe core damage risk the utility was interested in less grave consequences, e.g. the economic risks, causing significant extension of outages. The plant specific screening of initiators consisted of a study on the incident history and of interviewing the plant personnel on selected tasks. A number of thermohydraulic calculations were carried out to support the analysis of accident sequences. The operator actions after an initiating event were verified with the operating staff. The annual core damage risk from the refueling outage is about one forth of the total annual risk. The modifications decreased significantly the core damage frequency. It is foreseen that the SEPRA will form a basis of the procedure enhancement for the low power states. (author) 5 figs., 1 tab., 10 refs

Automatic machine-learning based identification of jogging periods from accelerometer measurements of adolescents under field conditions.

Science.gov (United States)

Zdravevski, Eftim; Risteska Stojkoska, Biljana; Standl, Marie; Schulz, Holger

2017-01-01

Assessment of health benefits associated with physical activity depend on the activity duration, intensity and frequency, therefore their correct identification is very valuable and important in epidemiological and clinical studies. The aims of this study are: to develop an algorithm for automatic identification of intended jogging periods; and to assess whether the identification performance is improved when using two accelerometers at the hip and ankle, compared to when using only one at either position. The study used diarized jogging periods and the corresponding accelerometer data from thirty-nine, 15-year-old adolescents, collected under field conditions, as part of the GINIplus study. The data was obtained from two accelerometers placed at the hip and ankle. Automated feature engineering technique was performed to extract features from the raw accelerometer readings and to select a subset of the most significant features. Four machine learning algorithms were used for classification: Logistic regression, Support Vector Machines, Random Forest and Extremely Randomized Trees. Classification was performed using only data from the hip accelerometer, using only data from ankle accelerometer and using data from both accelerometers. The reported jogging periods were verified by visual inspection and used as golden standard. After the feature selection and tuning of the classification algorithms, all options provided a classification accuracy of at least 0.99, independent of the applied segmentation strategy with sliding windows of either 60s or 180s. The best matching ratio, i.e. the length of correctly identified jogging periods related to the total time including the missed ones, was up to 0.875. It could be additionally improved up to 0.967 by application of post-classification rules, which considered the duration of breaks and jogging periods. There was no obvious benefit of using two accelerometers, rather almost the same performance could be achieved from

Automatic machine-learning based identification of jogging periods from accelerometer measurements of adolescents under field conditions.

Directory of Open Access Journals (Sweden)

Eftim Zdravevski

Full Text Available Assessment of health benefits associated with physical activity depend on the activity duration, intensity and frequency, therefore their correct identification is very valuable and important in epidemiological and clinical studies. The aims of this study are: to develop an algorithm for automatic identification of intended jogging periods; and to assess whether the identification performance is improved when using two accelerometers at the hip and ankle, compared to when using only one at either position.The study used diarized jogging periods and the corresponding accelerometer data from thirty-nine, 15-year-old adolescents, collected under field conditions, as part of the GINIplus study. The data was obtained from two accelerometers placed at the hip and ankle. Automated feature engineering technique was performed to extract features from the raw accelerometer readings and to select a subset of the most significant features. Four machine learning algorithms were used for classification: Logistic regression, Support Vector Machines, Random Forest and Extremely Randomized Trees. Classification was performed using only data from the hip accelerometer, using only data from ankle accelerometer and using data from both accelerometers.The reported jogging periods were verified by visual inspection and used as golden standard. After the feature selection and tuning of the classification algorithms, all options provided a classification accuracy of at least 0.99, independent of the applied segmentation strategy with sliding windows of either 60s or 180s. The best matching ratio, i.e. the length of correctly identified jogging periods related to the total time including the missed ones, was up to 0.875. It could be additionally improved up to 0.967 by application of post-classification rules, which considered the duration of breaks and jogging periods. There was no obvious benefit of using two accelerometers, rather almost the same performance could be

The Bulgaria before shut-down of next two blocks

International Nuclear Information System (INIS)

Dobak, D.

2005-01-01

The Ministry of Trade and Industry of United Kingdom in the frame of realization of programmes for the Middle and East Europe in the area of nuclear energetics during October 5 - 7, 2005 in Kozloduj has organized the Second International Conference on the theme 'Liquidation, social and economic changes'. In this paper author informs about Kozloduj NPP and plans for shut-down of this NPP as well as consequences of the shut-down. One of them the increase of unemployment and social impact for this region are presented

Primary shutdown system monitoring unit for nuclear power plants

International Nuclear Information System (INIS)

Khan, Tahir Kamal; Balasubramanian, R.; Agilandaeswari, K.

2013-01-01

Shut off rods made up of neutron absorbing material are used as Primary Shutdown System. To reduce the power of the reactor under certain abnormal operating conditions, these rods must go down into the core within a specified time. Any malfunctioning in the movement of rods cannot be tolerated and Secondary Shutdown System (SSS) must be actuated within stipulated time to reduce the reactor power. A special safety critical, hardwired electronics unit has been designed to detect failure of PSS Shut off rods movements and generate trip signals for initiating SSS. (author)

On line test of trip channels and actuators in primary shutdown system for RAPP-3,4/KAIGA-1,2 reactors

International Nuclear Information System (INIS)

Pramanik, M.; Gupta, P.K.; Ravi Prakash

1997-01-01

Several types of system design and logic arrangements have been used for reactor shutdown systems to avoid the possibility that a single failure within the trip channels/shutdown system actuators can prevent a shutdown system actuation. The trip channels and the logic arrangements associated with the shutdown systems use redundancy to allow them to continue to operate successfully even after having a certain number of failures. A periodic test is thus needed to detect and repair/replace failed elements to prevent accumulation and eventual system failure. The test must be capable of detecting the first failure. The design initiates shutdown system actuation by deenergising the logic relays and turning off the power to the final electrical actuators. Thus, the systems are fail safe with respect to loss of electrical power to the instruments, logic channels and the actuators. Several system/logic arrangements are used to reduce the chances of spurious actuation caused by the loss of a single power supply and other single failures. In general, the systems use coincidence of instrument channel trips and have separate power supplies for the individual instrument channel and dual power supplies where a single final control element is used. These features also permit on line test of instrument channels and logic train. On line test detects component failures not found by other means. The test determines whether gross failure has occurred rather than perform a calibration. As far as practicable the whole channel from sensors to logic and final control element is to be tested. (author)

Multi-unit shutdown due to boiler feedwater chemical excursion

International Nuclear Information System (INIS)

Diebel, M.E.

1991-01-01

Ontario Hydro's Bruce Nuclear Generating Station 'B' consists of four 935 W CANDU units located on the east shore of Lake Huron in the province of Ontario, Canada. On July 25 and 26, 1989 three of the four operating units were shutdown due to boiler feedwater chemical excursions initiated by a process upset in the Water Treatment Plant that provides demineralized make-up water to all four units. The chemicals that escaped from an ion exchange vessel during a routine regeneration very quickly spread through the condensate make-up system and into the boiler feedwater systems. This resulted in boiler sulfate levels exceeding shutdown limits. A total of 260 GWH of electrical generation was unexpectedly made unavailable to the grid at a time of peak seasonal demand. This event exposed several unforeseen deficiencies and vulnerabilities in the automatic demineralized water make-up quality protection scheme, system designs, operating procedures and the ability of operating personnel to recognize and appropriately respond to such an event. The combination of these factors contributed towards turning a minor system upset into a major multi-unit shutdown. This paper provides the details of the actual event initiation in the Water Treatment Plant and describes the sequence of events that led to the eventual shutdown of three units and near shutdown of the fourth. The design inadequacies, procedural deficiencies and operating personnel responses and difficulties are described. The process of recovering from this event, the flushing out of system piping, boilers and the feedwater train is covered as well as our experiences with setting up supplemental demineralized water supplies including trucking in water and the use of rental trailer mounted demineralizing systems. System design, procedural and operational changes that have been made and that are still being worked on in response to this event are described. The latest evidence of the effect of this event on boiler tube

Standardization of the time for the execution of HANARO start-up and shutdown procedures

International Nuclear Information System (INIS)

Choi, H. Y.; Lim, I. C.; Hwang, S. R.; Kang, T. J.; Youn, D. B.

2003-01-01

For the standardization of the time to execute HANARO start-up and shutdown procedures, code names were assigned to the individual procedures and the work time were investigated. The data recorded by the operators during start-up and shutdown were statistically analyzed. The analysis results will be used for the standardization of start-up and shutdown procedures and it will be reflected in the procedure document

Shutdown risk management applied at Philadelphia Electric Company

International Nuclear Information System (INIS)

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

2004-01-01

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

Probabilistic safety assessments of nuclear power plants for low power and shutdown modes

International Nuclear Information System (INIS)

2000-03-01

Within the past several years the results of nuclear power plant operating experience and performance of probabilistic safety assessments (PSAs) for low power and shutdown operating modes have revealed that the risk from operating modes other than full power may contribute significantly to the overall risk from plant operations. These early results have led to an increased focus on safety during low power and shutdown operating modes and to an increased interest of many plant operators in performing shutdown and low power PSAs. This publication was developed to provide guidance and insights on the performance of PSA for shutdown and low power operating modes. The preparation of this publication was initiated in 1994. Two technical consultants meetings were conducted in 1994 and one in February 1999 in support of the development of this report

Optimal test intervals for shutdown systems for the Cernavoda nuclear power station

International Nuclear Information System (INIS)

Negut, Gh.; Laslau, F.

1993-01-01

Cernavoda nuclear power station required a complete PSA study. As a part of this study, an important goal to enhance the effectiveness of the plant operation is to establish optimal test intervals for the important engineering safety systems. The paper presents, briefly, the current methods to optimize the test intervals. For this reason it was used Vesely methods to establish optimal test intervals and Frantic code to survey the influence of the test intervals on system availability. The applications were done on the Shutdown System no. 1, a shutdown system provided whit solid rods and on Shutdown System no. 2 provided with injecting poison. The shutdown systems receive nine total independent scram signals that dictate the test interval. Fault trees for the both safety systems were developed. For the fault tree solutions an original code developed in our Institute was used. The results, intended to be implemented in the technical specifications for test and operation of Cernavoda NPS are presented

The shutdown reactor: Optimizing spent fuel storage cost

International Nuclear Information System (INIS)

Pennington, C.W.

1995-01-01

Several studies have indicated that the most prudent way to store fuel at a shutdown reactor site safely and economically is through the use of a dry storage facility licensed under 10CFR72. While such storage is certainly safe, is it true that the dry ISFSI represents the safest and most economical approach for the utility? While no one is really able to answer that question definitely, as yet, Holtec has studied this issue for some time and believes that both an economic and safety case can be made for an optimization strategy that calls for the use of both wet and dry ISFSI storage of spent fuel at some plants. For the sake of brevity, this paper summarizes some of Holtec's findings with respect to the economics of maintaining some fuel in wet storage at a shutdown reactor. The safety issue, or more importantly the perception of safety of spent fuel in wet storage, still varies too much with the eye of the beholder, and until a more rigorous presentation of safety analyses can be made in a regulatory setting, it is not practically useful to argue about how many angels can sit on the head of a safety-related pin. Holtec is prepared to present such analyses, but this does not appear to be the proper venue. Thus, this paper simply looks at certain economic elements of a wet ISFSI at a shutdown reactor to make a prima facie case that wet storage has some attractiveness at a shutdown reactor and should not be rejected out of hand. Indeed, an optimization study at certain plants may well show the economic vitality of keeping some fuel in the pool and converting the NRC licensing coverage from 10CFR50 to 10CFR72. If the economics look attractive, then the safety issue may be confronted with a compelling interest

MCR2S unstructured mesh capabilities for use in shutdown dose rate analysis

International Nuclear Information System (INIS)

Eade, T.; Stonell, D.; Turner, A.

2015-01-01

Highlights: • Advancements in shutdown dose rate calculations will be needed as fusion moves from experimental reactors to full scale demonstration reactors in order to ensure the safety of personnel. • The MCR2S shutdown dose rate tool has been modified to allow shutdown dose rates calculations using an unstructured mesh. • The unstructured mesh capability of MCR2S was used on three shutdown dose rate models, a simple sphere, the ITER computational benchmark and the DEMO computational benchmark. • The results showed a reasonable agreement between an unstructured mesh approach and the CSG approach and highlighted the need to carefully choose the unstructured mesh resolution. - Abstract: As nuclear fusion progresses towards a sustainable energy source and the power of tokamak devices increases, a greater understanding of the radiation fields will be required. As well as on-load radiation fields, off-load or shutdown radiation field are an important consideration for the safety and economic viability of a commercial fusion reactor. Previously codes such as MCR2S have been written in order to predict the shutdown dose rates within, and in regions surrounding, a fusion reactor. MCR2S utilises a constructive solid geometry (CSG) model and a superimposed structured mesh to calculate 3-D maps of the shutdown dose rate. A new approach to MCR2S calculations is proposed and implemented using a single unstructured mesh to replace both the CSG model and the superimposed structured mesh. This new MCR2S approach has been demonstrated on three models of increasing complexity. These models were: a sphere, the ITER computational shutdown dose rate benchmark and the DEMO computational shutdown dose rate benchmark. In each case the results were compared to MCR2S calculations performed using MCR2S with CSG geometry and a superimposed structured mesh. It was concluded that the results from the unstructured mesh implementation of MCR2S compared well to the CSG structured mesh

On line testing of shutdown system

International Nuclear Information System (INIS)

Ramnath, S.; Swaminathan, P.; Sreenivasan, P.

1997-01-01

For ensuring high reliability and availability, safety related Instrumentation channels are triplicated. Solid state electronics can fail in safe or unsafe mode. Hence, it is necessary to supervise the safety related Instrumentation channels from sensor to final shutdown system. Microprocessor/ Microcontroller/ ASIC based online supervision systems are detailed in this paper. (author)

78 FR 38739 - Standard Format and Content for Post-Shutdown Decommissioning Activities Report

Science.gov (United States)

2013-06-27

... NUCLEAR REGULATORY COMMISSION [NRC-2012-0299] Standard Format and Content for Post-Shutdown Decommissioning Activities Report AGENCY: Nuclear Regulatory Commission. ACTION: Regulatory guide; issuance..., ``Standard Format and Content for Post-shutdown Decommissioning Activities Report.'' This guide describes a...

Development of Start-up and Shutdown Procedure for the HANARO Fuel Test Loop

International Nuclear Information System (INIS)

Park, S. K.; Sim, B. S.; Chi, D. Y.; Lee, J. M.; Lee, C. Y.; Ahn, S. H.

2009-06-01

A start-up and shutdown procedure for the HANARO fuel test loop has been developed. This is a facility for fuel and material irradiation tests. The facility provides experimental conditions similar to the normal operational pressures and temperatures of commercial PWR and CANDU plants. The normal operation modes of the HANARO fuel test loop are classified into loop shutdown, cold stand-by 1, cold stand-by 2, hot stand-by, and hot operation. The operation modes depend on the fission power of test fuels and the coolant temperature at the inlet of the in-pile test section. The HANARO must maintain a shutdown mode if the HANARO fuel test loop is loop shutdown, cold stand-by 1, cold stand-by 2, or hot stand-by. As the HANARO becomes power operation mode, the operation mode of the HANARO fuel test loop comes to hot operation from hot stand-by. The procedure for the HANARO fuel test loop consists of four main parts such as check of initial conditions, stat-up operation procedure, shutdown operation procedure, and check lists for operations. Several hot test operations ensure that the procedure is appropriate

Absence of periodic orbits in digital memcomputing machines with solutions

Science.gov (United States)

Di Ventra, Massimiliano; Traversa, Fabio L.

2017-10-01

In Traversa and Di Ventra [Chaos 27, 023107 (2017)] we argued, without proof, that if the non-linear dynamical systems with memory describing the class of digital memcomputing machines (DMMs) have equilibrium points, then no periodic orbits can emerge. In fact, the proof of such a statement is a simple corollary of a theorem already demonstrated in Traversa and Di Ventra [Chaos 27, 023107 (2017)]. Here, we point out how to derive such a conclusion. Incidentally, the same demonstration implies absence of chaos, a result we have already demonstrated in Di Ventra and Traversa [Phys. Lett. A 381, 3255 (2017)] using topology. These results, together with those in Traversa and Di Ventra [Chaos 27, 023107 (2017)], guarantee that if the Boolean problem the DMMs are designed to solve has a solution, the system will always find it, irrespective of the initial conditions.

Non-conventional rule of making a periodically varying different-pole magnetic field in low-power alternating current electrical machines with using ring coils in multiphase armature winding

Science.gov (United States)

Plastun, A. T.; Tikhonova, O. V.; Malygin, I. V.

2018-02-01

The paper presents methods of making a periodically varying different-pole magnetic field in low-power electrical machines. Authors consider classical designs of electrical machines and machines with ring windings in armature, structural features and calculated parameters of magnetic circuit for these machines.

CV activities on the LHC complex during the long shutdown

CERN Document Server

Deleval, S; Body, Y; Obrecht, M; Moccia, S; Peon, G

2011-01-01

The presentation gives an overview of the major projects and work foreseen to be performed during next long shutdown on cooling and ventilation plants. Several projects are needed following the experience of the last years when LHC was running, in particular the modifications in the water cooling circuits presently in overflow. Some other projects are linked to the CV consolidation plan. Finally, most of the work shall be done to respond to additional requests: SR buildings air conditioning, the need to be able to clean and maintain the LHC cooling towers without a complete stop of cooling circuits, the upgrade of the air conditioning of the CCC rack room cooling etc. For all these activities, the author will detail constraints and the impact on the schedule and on the operation of the plants that will however need to run for most of the shutdown duration. The consequence of postponing the long shutdown from 2012 to 2013 will be also covered.

TRACG-CFD analysis of ESBWR reactor water cleanup shutdown cooling system mixing coefficient

International Nuclear Information System (INIS)

Gallardo, J.; Marquino, W.; Mistreanu, A.; Yang, J.

2015-09-01

The ESBWR is a 1520 nominal [M We] Generation III+ natural circulation boiling water reactor designed to high levels of safety utilizing features that have been successfully used before in operating BWRs, as well as standard features common to A BWR. In September of 2014, the US NRC has certified the ESBWR design for use in the USA. The RWCU/Sdc is an auxiliary system for the ESBWR nuclear island. Basic functions it performs include purifying the reactor coolant during normal operation and shutdown and providing shutdown cooling and cooldown to cold shutdown conditions. The performance of the RWCU system during shutdown cooling is directly related to the temperature of the water removed through the outlets, which is coupled with the vessel and F W temperatures through a thermal mixing coefficient. The complex three-dimensional (3-D) geometry of the BWR downcomer and lower plenum has a great impact on the flow mixing. Only a fine mesh technique like CFD can predict the 3-D temperature distribution in the RPV during shutdown and provide the RWCU/Sdc system inlet temperature. Plant shutdown is an unsteady event by nature and was modeled as a succession of CFD steady-state simulations. It is required to establish the mixing coefficient (which is a function of the heat balance and the core flow) during the operation of the RWCU system in the multiple shutdown cooling modes, and therefore a range of core flows needs to be estimated using quasi steady states obtained with TRACG. The lower end of that range is obtained from a system with minimal power decay heat and core flow; while the higher end corresponds to the power at the beginning of RWCU/Sdc operation when the cooldown is transferred to the RWCU/Sdc after the initial depressurization via the turbine bypass valves. Because the ESBWR RWCU/Sdc return and suction designs provide good mixing, the uniform mixing energy balance was found to be an adequate alternative for deriving the mixing coefficient. The CFD mass flow

TRACG-CFD analysis of ESBWR reactor water cleanup shutdown cooling system mixing coefficient

Energy Technology Data Exchange (ETDEWEB)

Gallardo, J. [UNAM, Facultad de Ingenieria, Ciudad Universitaria, 04510 Ciudad de Mexico (Mexico); Marquino, W.; Mistreanu, A.; Yang, J., E-mail: euqrop@hotmail.com [General Electric Hitachi Nuclear Energy, Wilmington, 28401 North Carolina (United States)

2015-09-15

The ESBWR is a 1520 nominal [M We] Generation III+ natural circulation boiling water reactor designed to high levels of safety utilizing features that have been successfully used before in operating BWRs, as well as standard features common to A BWR. In September of 2014, the US NRC has certified the ESBWR design for use in the USA. The RWCU/Sdc is an auxiliary system for the ESBWR nuclear island. Basic functions it performs include purifying the reactor coolant during normal operation and shutdown and providing shutdown cooling and cooldown to cold shutdown conditions. The performance of the RWCU system during shutdown cooling is directly related to the temperature of the water removed through the outlets, which is coupled with the vessel and F W temperatures through a thermal mixing coefficient. The complex three-dimensional (3-D) geometry of the BWR downcomer and lower plenum has a great impact on the flow mixing. Only a fine mesh technique like CFD can predict the 3-D temperature distribution in the RPV during shutdown and provide the RWCU/Sdc system inlet temperature. Plant shutdown is an unsteady event by nature and was modeled as a succession of CFD steady-state simulations. It is required to establish the mixing coefficient (which is a function of the heat balance and the core flow) during the operation of the RWCU system in the multiple shutdown cooling modes, and therefore a range of core flows needs to be estimated using quasi steady states obtained with TRACG. The lower end of that range is obtained from a system with minimal power decay heat and core flow; while the higher end corresponds to the power at the beginning of RWCU/Sdc operation when the cooldown is transferred to the RWCU/Sdc after the initial depressurization via the turbine bypass valves. Because the ESBWR RWCU/Sdc return and suction designs provide good mixing, the uniform mixing energy balance was found to be an adequate alternative for deriving the mixing coefficient. The CFD mass flow

Republic of Korea: Design Study for Passive Shutdown System of the PGSFR

International Nuclear Information System (INIS)

Lee, J.H.

2015-01-01

There have been no experiences of implementing a passive shutdown system in operating or operated SFRs around the world. However, new SFRs are considered to adopt a self-actuated shutdown system (SASS) in the future to provide an alternate means of passively shutting down the reactor. The Prototype Gen-IV SFR (PGSFR) developed by KAERI also adopts this system for the same reason. This passive shutdown design concept is combined with a group of secondary control rod drive mechanisms (SCRDM). The system automatically releases the control rod assembly (CRA) around the set temperature, and then drops the CRA by gravity without any external control signals and any actuating power in an emergency of the reactor. This paper describes the parametric design study of a passive shutdown system, which consists of a thermal expansion device, an electromagnet, and a secondary control rod assembly head. The conceptual design values of each component are also suggested. Parametric calculations are performed to check the suitability of the performance requirements of the thermal expansion device and electromagnets

Fuel Supply Shutdown Facility Interim Operational Safety Requirements

International Nuclear Information System (INIS)

BENECKE, M.W.

2000-01-01

The Interim Operational Safety Requirements for the Fuel Supply Shutdown (FSS) Facility define acceptable conditions, safe boundaries, bases thereof, and management of administrative controls to ensure safe operation of the facility

Reliability analysis of self-actuated shutdown system

International Nuclear Information System (INIS)

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

1991-01-01

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

78 FR 49553 - Three Mile Island, Unit 2; Post Shutdown Decommissioning Activities Report

Science.gov (United States)

2013-08-14

... NUCLEAR REGULATORY COMMISSION [Docket No. 50-320; NRC-2013-0183] Three Mile Island, Unit 2; Post Shutdown Decommissioning Activities Report AGENCY: Nuclear Regulatory Commission. ACTION: Notice of receipt... Shutdown Decommissioning Activity Report (PSDAR) for Three Mile Island, Unit 2 (TMI-2). The PSDAR provides...

Startup, Shutdown, & Malfunction (SSM) Emissions at Industrial Facilities

Science.gov (United States)

EPA issued a final action to ensure states have plans in place that are fully consistent with the Clean Air Act and recent court decisions concerning startup, shutdown and malfunction (SSM) operations.

Elementary calculation of the shutdown delay of a pile

International Nuclear Information System (INIS)

Yvon, J.

1949-04-01

This study analyzes theoretically the progress of the shutdown of a nuclear pile (reactor) when a cadmium rod is introduced instantaneously. For simplification reasons, the environment of the pile is considered as homogenous and only thermal neutrons are considered (delayed neutrons are neglected). Calculation is made first for a plane configuration (plane vessel, plane multiplier without reflector, and plane multiplier with reflector), and then for a cylindrical configuration (multiplier without reflector, multiplier with infinitely thick reflector, finite cylindrical piles without reflector and with reflector). The self-sustain conditions are calculated for each case and the multiplication length and the shutdown delay are deduced. (J.S.)

Fast plasma shutdown by killer pellet injection in JT-60U with reduced heat flux on the divertor plate and avoiding runaway electron generation

International Nuclear Information System (INIS)

Yoshino, R.; Kondoh, T.; Neyatani, Y.; Itami, K.; Kawano, Y.; Isei, N.

1997-01-01

A killer pellet is an impurity pellet that is injected into a tokamak plasma in order to terminate a discharge without causing serious damage to the tokamak machine. In JT-60U neon ice pellets have been injected into OH and NB heated plasmas and fast plasma shutdowns have been demonstrated without large vertical displacement. The heat pulse on the divertor plate has been greatly reduced by killer pellet injections (KPI), but a low-power heat flux tail with a long time duration is observed. The total energy on the divertor plate increases with longer heat flux tail, so it has been reduced by shortening the tail. Runaway electron (RE) generation has been observed just after KPI and/or in the later phase of the plasma current quench. However, RE generation has been avoided when large magnetic perturbations are excited. These experimental results clearly show that KPI is a credible fast shutdown method avoiding large vertical displacement, reducing heat flux on the divertor plate, and avoiding (or minimizing) RE generation. (Author)

Reload safety evaluation of boron dilution accident related to shutdown margin proportional to boron concentration

International Nuclear Information System (INIS)

Zee, Sung Kyun; Lee, Ki Bog; Song, Jae Woong

1993-06-01

This report investigates the efficient safety evaluation method and analysis procedure on Boron Dilution Accident(BDA) under the proportional shutdown margin to boron concentration. Also investigated are problems caused by applying this shutdown margin limit. Through this investigation, the safety of Kori-3 Cycle-8, Yonggwang-2 Cycle-7, Kori-4 Cycle-8 and Yonggwang-1 Cycle-8 with respect to BDA is verified. In order to satisfy the shutdown margin requirement in the Technical Specifications, it is shown that the High Flux Alarm at Shutdown Setting for Kori-4 Cycle-8 and Yonggwang-1 Cycle-8 at Mode 5 should be set at 2 or the Technical Specification should be revised. (Author)

Preliminary Evaluation of Removing Used Nuclear Fuel from Shutdown Sites

Energy Technology Data Exchange (ETDEWEB)

Maheras, Steven J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Best, Ralph E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Ross, Steven B. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Buxton, Kenneth A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); England, Jeffery L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); McConnell, Paul E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Massaro, Lawrence M. [Federal Railroad Administration (FRA) (United States); Jensen, Philip J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2014-10-01

This report presents a preliminary evaluation of removing used nuclear fuel (UNF) from 12 shutdown nuclear power plant sites. At these shutdown sites the nuclear power reactors have been permanently shut down and the sites have been decommissioned or are undergoing decommissioning. The shutdown sites are Maine Yankee, Yankee Rowe, Connecticut Yankee, Humboldt Bay, Big Rock Point, Rancho Seco, Trojan, La Crosse, Zion, Crystal River, Kewaunee, and San Onofre. The evaluation was divided into four components: characterization of the UNF and greater-than-Class C low-level radioactive waste (GTCC waste) inventory; a description of the on-site infrastructure and conditions relevant to transportation of UNF and GTCC waste; an evaluation of the near-site transportation infrastructure and experience relevant to shipping transportation casks containing UNF and GTCC waste, including identification of gaps in information; and, an evaluation of the actions necessary to prepare for and remove UNF and GTCC waste. The primary sources for the inventory of UNF and GTCC waste are the U.S. Department of Energy (DOE) RW-859 used nuclear fuel inventory database, industry sources such as StoreFUEL and SpentFUEL, and government sources such as the U.S. Nuclear Regulatory Commission. The primary sources for information on the conditions of site and near-site transportation infrastructure and experience included observations and information collected during visits to the Maine Yankee, Yankee Rowe, Connecticut Yankee, Humboldt Bay, Big Rock Point, Rancho Seco, Trojan, La Crosse, and Zion sites; information provided by managers at the shutdown sites; Facility Interface Data Sheets compiled for DOE in 2005; Services Planning Documents prepared for DOE in 1993 and 1994; industry publications such as Radwaste Solutions; and Google Earth. State and Regional Group representatives, a Tribal representative, and a Federal Railroad Administration representative participated in six of the shutdown site

Extending reactor time-to-poison and reducing poison shutdown time by pre-shutdown power alterations

Energy Technology Data Exchange (ETDEWEB)

Kerr, Edward

1963-10-15

Manipulation of reactor power prior to shutdown and increasing the time- to-poison a sufficient amount to enable the required maintenance work to be completed and the reactor immediately restarted are discussed. The method employed in the NRU Reactor to gain the maximum timeto-poison with the least production loss is outlined. The method is based on intuition and is described by means of an analog of the iodine--xenon equations rather than the equations themselves. (C.E.S.)

Trends vs. reactor size of passive reactivity shutdown and control performance

International Nuclear Information System (INIS)

Wade, D.C.; Fujita, E.K.

1988-01-01

The focus of the US advanced reactor program since the cancellation of CRBR has been on inherent safety and cost reduction. The notion is to so design the reactor that in the event of an off normal condition, it brings itself to a safe shutdown condition and removes decay heat by reliance on ''inherent processes'' i.e., without reliance on devices requiring switching and outside sources of power. Such a reactor design would offer the potential to eliminate costly ''Engineered Safety Features,'' to lower capital costs, and to assuage public unease concerning reactor safety. For LMR concepts, the goal of passive reactivity shutdown has been approached in the US by designing the reactors for favorable relationships among the power, power/flow, and inlet temperature coefficients of reactivity, for high internal conversion ratio (yielding small burnup control swing), and for a primary pump coastdown time appropriately matched to the delayed neutron hold back of power decay upon negative reactivity input. The use of sodium bonded metallic fuel pins has facilitated the achievement of the passive shutdown design goals as a consequence of their high thermal conductivity and high effective heavy metal density. Alternately, core designs based on derated oxide pins may be able to achieve the passive shutdown features at the cost of larger core volume and increased initial fissile inventory. 8 refs., 12 figs., 1 tab

Seismic qualification of SPX1 shutdown systems - tests and calculations

International Nuclear Information System (INIS)

Brochard, D.; Buland, P.

1988-01-01

The SUPERPHENIX 1 shutdown system is composed of two main systems: the Complementary Shutdown System SAC (Systeme d'Arret Complementaire) and the Primary Shutdown System (SCP) (Systeme de Commande Principal). In case of a seismic event, the insertability of the different shutdown systems has to be demonstrated. Tests have been performed on the SAC and have shown that this system was not sensitive to the seismic excitation (the drop time increases of 10% at SSE level). For the SCP, as an analytical demonstration was felt difficult to achieve, it was decided to perform a full scale testing program. These tests have been performed for the two types of SCP which are present in Superphenix: SCP 1 (Creusot Loire design), SCP 2 (Novatome design). As there was no existing facility in France to test this kind of slender structure (21 metres high) a new facility named VESUBIE was designed and installed in an existing pit located at the Saclay nuclear research center. The objectives of the tests were the following: to demonstrate insertability of control rod; to demonstrate absence of seismic induced damage to the SCP; to measure increase of scram time; to measure seismic induced stresses; to obtain data for code correlation. After completion of the tests, measurements have been correlated with results obtained from a non-linear finite element model. Time history correlations were achieved for SCP 1. Afterwards a calculation was performed in hot condition to find if there was some effect of temperature on SCP seismic response. 2 refs, 8 figs

Evaluation of reactivity shutdown margin for nuclear fuel reload optimization

International Nuclear Information System (INIS)

Wong, Hing-Ip; Maldonado, G.I.

1995-01-01

The FORMOSA-P code is a nuclear fuel management optimization package that combines simulated annealing (SA) and nodal generalized perturbation theory (GPT). Recent studies at Electricite de France (EdF-Clamart) have produced good results for power-peaking minimizations under multiple limiting control rod configurations. However, since the reactivity shutdown margin is not explicitly treated as an objective or constraint function, then any optimal loading patterns (LPs) are not guaranteed to yield an adequate shutdown margin (SDM). This study describes the implementation of the SDM calculation within a FORMOSA-P optimization. Maintaining all additional computational requirements to a minimum was a key consideration

Component failures that lead to manual shutdowns

International Nuclear Information System (INIS)

1979-01-01

The data for this report are taken from a population of thirty-five LWRs, al of which differ appreciably in size, design, and age. Appendix A provides a graphical display of the number of manual shutdowns per operating year as a function of plant age, with the frequency adjusted to reflect plant availability

Impacts of reactivity feedback uncertainties on inherent shutdown in innovative designs

International Nuclear Information System (INIS)

Mueller, C.J.

1986-01-01

The concept of inherent shutdown is emphasized in the approach to the design of innovative, small pool-type liquid-metal reactors (LMRs). This paper reports an evaluation of reactivity feedback uncertainties used in the analyses of anticipated transients without scram for innovative LMRs, and the associated impacts on safety margins and inherent shutdown success probabilities on unprotected loss-of-flow (LOF) events. It then assesses the ultimate importance of these uncertainties on LOF and transient overpower events in evolving metal and oxide innovative designs

Impacts of reactivity feedback uncertainties on inherent shutdown in innovative designs

International Nuclear Information System (INIS)

Mueller, C.J.

1986-01-01

The concept of ''inherent shutdown'' is emphasized in the approach to the design of innovative, small pool-type liquid metal reactors (LMRs). This paper reports an evaluation of reactivity feedback uncertainties used in the analyses of anticipated transients without scram (ATWS) for innovative LMRs, and the associated impacts on safety margins and inherent shutdown success probabilities on unprotected loss-of-flow (LOF) events. It then assesses the ultimate importance of these uncertainties on LOF and transient overpower (TOP) events in evolving metal and oxide innovative designs

Computerized operator support system with new man-machine interface for BWR power plants

International Nuclear Information System (INIS)

Monta, K.; Naito, N.; Sugawara, M.; Sato, N.; Mori, N.; Tai, I.; Fukumoto, A.; Tsuchida, M.

1984-01-01

Improvement of the man-machine interface of nuclear power plants is an important contribution to the further enhancement of operational safety. In addition, recent advances in computer technology seem to offer the greatest opportunity to date for achieving improvement in the man-machine interface. The development of a computerized operator support system for BWRs has been undertaken since 1980 with the support of the Japanese Government. The conceptual design of this system is based on the role of the operators. The main functions are standby system management, disturbance analysis and post-trip operational guidance. The objective of the standby system management is to monitor the standby status of the engineered safety feature during normal operation to assure its proper functioning at the onset of emergency situations. The disturbance analysis system detects disturbances in the plant in their early stages and informs the plant operators about, for example, the cause of the disturbances, the plant status and possible propagations. Consequently, operators can take corrective actions to prevent unnecessary plant shutdown. The objective of the post trip operational guide is to support operators in diagnosis and corrective action after a plant trip. Its functions are to monitor the performance of the engineered safety feature, to identify the plant status and to guide the appropriate corrective action to achieve safe plant shutdown. The information from the computerized operator support system is supplied to operators through a colour CRT operator console. The authors have evaluated the performance of various new man-machine interfacing tools and proposed a new operator console design. A prototype system has been developed and verification/validation is proceeding with a BWR plant simulator. (author)

Evaluation of power behavior during startup and shutdown procedures of the IPR-R1 Triga Reactor

International Nuclear Information System (INIS)

Zangirolami, Dante M.; Mesquita, Amir Z.; Ferreira, Andrea V.

2009-01-01

The IPR-R1 nuclear reactor of Centro de Desenvolvimento da Tecnologia Nuclear - CDTN/CNEN is a TRIGA Mark I pool type reactor cooled by natural circulation of light water. In the IPR-R1, the power is measured by four nuclear channels, neutron-sensitive chambers, which are mounted around the reactor core: the Startup Channel for power indication during reactor startup; the Logarithmic Wide Range Power Monitoring Channel; the Linear Multi-Range Power Monitoring Channel and the Percent Power Safety Channel. A data acquisition system automatically does the monitoring and storage of all the reactor operational parameters including the reactor power. The startup procedure is manual and the time to reach the desired reactor power level is different on each irradiation which may introduces differences in induced activity of samples irradiated in different irradiations. In this work, the power evolution during startup and shutdown periods of IPR-R1 operation was evaluated and the mean values of reactor energy production in these operational phases were obtained. The analyses were performed on basis of the Linear Multi-Range Channel data. The results show that the sum of startup and shutdown periods corresponds to 1% of released energy for irradiations during 1h at 100kW. This value may be useful to correct experimental data in neutron activation experiments. (author)

Transient fission-product release during reactor shutdown and startup

International Nuclear Information System (INIS)

Hunt, C.E.L.; Lewis, B.J.; Dickson, L.W.

1997-12-01

Sweep-gas experiments performed at AECL's Chalk River Laboratories from 1979 to 1985 have been further analysed to determine the fraction of the gaseous fission-product inventory that is released on reactor shutdown and startup. Empirical equations were derived and applied to calculate the stable xenon release from companion fuel elements and from a well-documented experimental fuel bundle irradiated in the NRU reactor. The calculated gas release could be matched to the measured values within about a factor of two for an experimental irradiation with a burnup of 217 MWh/kgU. There was also limited information on the fraction of the radioactive iodine that was exposed, but not released, on reactor shutdown. An empirical equation is proposed for calculating this fraction. (author)

Accident sequence analysis for a BWR [Boiling Water Reactor] during low power and shutdown operations

International Nuclear Information System (INIS)

Whitehead, D.W.; Hake, T.M.

1990-01-01

Most previous Probabilistic Risk Assessments have excluded consideration of accidents initiated in low power and shutdown modes of operation. A study of the risk associated with operation in low power and shutdown is being performed at Sandia National Laboratories for a US Boiling Water Reactor (BWR). This paper describes the proposed methodology for the analysis of the risk associated with the operation of a BWR during low power and shutdown modes and presents preliminary information resulting from the application of the methodology. 2 refs., 2 tabs

Loss of shutdown cooling during degassing in Doel 1

International Nuclear Information System (INIS)

1996-01-01

The presentation describes loss of shutdown cooling event during degassing in Doel 1 reactor, including description of Doel 1 features,status of plant prior to incident, event sequence and incident causes

Comparison of Qualitative and Quantitative Risk Results for Shutdown Operation

International Nuclear Information System (INIS)

Oh, Hae Cheol; Kim, Myung Ki; Chung, Bag Soon; Seo, Mi Ro; Hong, Sung Yull

2006-01-01

The Defense-In-Depth philosophy is a fundamental concept of nuclear safety. The objective of Defense-In- Depth (DID) evaluation is to assess the level of Defense- In-Depth maintained during the various plant maintenance activities. Especially for shutdown and outage operations, the Defense-In-Depth might be challenged due to the reduction in redundancy and diversity resulting from the maintenance. The qualitative defense-in-depth evaluation using deterministic trees such as SFAT (Safety Function Assessment Tree), can provide 'Safety' related information on the levels of defense-in-depth according to the plant configuration including the levels of redundancy and diversity. For the more reasonable color decision of SFAT, it is necessary to identify the risk impact of degradation of redundancy and diversity of mitigation systems. The probabilistic safety analysis for the shutdown status can provide risk information related on the degradation of redundancy and diversity level for the safety functions during outage. Insights from the both methods for the plant status can be the same or different. The results of DID approach and PSA for the shutdown state are compared in this paper

Evaluation of reactivity shutdown margin for nuclear fuel reload optimization

International Nuclear Information System (INIS)

Engrand, P.; Wong, H. I.; Maldonado, G.I.

1996-01-01

The FORMOSA-P code is a nuclear fuel management optimization package which combines simulated annealing (SA) and nodal generalized perturbation theory (GPT). Recent studies at Electricite de France have produced good results for power peaking minimizations under multiple limiting control rod configurations. However, since the reactivity shutdown margin is not explicitly treated as an objective or constraint function, then any optimal loading patterns (LPs) are not guaranteed to yield an adequate shutdown margin (SDM). This study describes the implementation of the SDM calculation within a FORMOSA-P optimization. Maintaining all additional computational requirements to a minimum was a key consideration. (authors). 4 refs., 2 figs

Impact of shutdown risk on risk-based assessment of technical specifications

International Nuclear Information System (INIS)

Deriot, S.

1992-10-01

This paper describes the current work performed by the Research and Development Division of EDF concerning risk-based assessment of Operating Technical Specifications (OTS). The current risk-based assessment of OTS at EDF is presented. Then, the level 1 Probabilistic Safety Assessment of unit 3 of the Paluel nuclear power station (called PSA 1300) is described. It is fully computerized and takes into account the risk in shutdown states. A case study is presented. It shows that the fact of considering shutdown risk suggests that the current OTS should be modified

Tricon hardware controller implementation of CANDU nuclear power plant shutdown system

International Nuclear Information System (INIS)

Zahedi, P.

2007-01-01

This paper introduces the implementation of logic functions associated with the shutdown systems of CANDU nuclear power plants. The experimental aspects of this work include development of control program embedded in shutdown systems of CANDU based NPPs. A physical test environment is designed to simulate the measurements of in-core flux detector (ICFD) and ion chamber (I/C) signals. The programmable logic used in this experimentation provides Triple Modular Redundant (TMR) architecture as well as a voting mechanism used upon execution of control program on each independent channel. (author)

Reserves for shutdown/dismantling and disposal in nuclear technology. Theses and recommendations on reform options

International Nuclear Information System (INIS)

Meyer, Bettina

2012-01-01

The study on reserves for shutdown, dismantling and disposal of nuclear facilities covers the following topics: cost for shutdown, dismantling and disposal and amount and transparency of nuclear reserves, solution by y stock regulated by public law for long-term liabilities, and improvement of the protection in the event of insolvency for the remaining EVU reserves for short- and intermediate-term liabilities. The appendix includes estimations and empirical values for the cost of shutdown and dismantling, estimation of disposal costs, and a summary of Swiss studies on dismantling and disposal and transfer to Germany.

Fuel supply shutdown facility interim operational safety requirements

International Nuclear Information System (INIS)

Besser, R.L.; Brehm, J.R.; Benecke, M.W.; Remaize, J.A.

1995-01-01

These Interim Operational Safety Requirements (IOSR) for the Fuel Supply Shutdown (FSS) facility define acceptable conditions, safe boundaries, bases thereof, and management or administrative controls to ensure safe operation. The IOSRs apply to the fuel material storage buildings in various modes (operation, storage, surveillance)

300 Area fuel supply shutdown facility hazards assessment

International Nuclear Information System (INIS)

Campbell, L.R.

1998-01-01

This document establishes the technical basis in support of Emergency Planning activities for the 300 Area Fuel Supply Shutdown Facilities on the Hanford Site. Through this document, the technical basis for the development of facility specific Emergency Action Levels and Emergency Planning Zone, is demonstrated

Controlled shutdown of a fuel cell

Science.gov (United States)

Clingerman, Bruce J.; Keskula, Donald H.

2002-01-01

A method is provided for the shutdown of a fuel cell system to relieve system overpressure while maintaining air compressor operation, and corresponding vent valving and control arrangement. The method and venting arrangement are employed in a fuel cell system, for instance a vehicle propulsion system, comprising, in fluid communication, an air compressor having an outlet for providing air to the system, a combustor operative to provide combustor exhaust to the fuel processor.

Self-actuated shutdown system for a commercial size LMFBR. Final report

Energy Technology Data Exchange (ETDEWEB)

Dupen, C.F.G.

1978-08-01

A Self-Actuated Shutdown System (SASS) is defined as a reactor shutdown system in which sensors, release mechanisms and neutron absorbers are contained entirely within the reactor core structure, where they respond inherently to abnormal local process conditions, by shutting down the reactor, independently of the plant protection system (PPS). It is argued that a SASS, having a response time similar to that of the PPS, would so reduce the already very low probability of a failure-to-scram event that costly design features, derived from core disruptive accident analysis, could be eliminated. However, the thrust of the report is the feasibility and reliability of the in-core SASS hardware to achieve sufficiently rapid shutdown. A number of transient overpower and transient undercooling-responsive systems were investigated leading to the selection of a primary candidate and a backup concept. During a transient undercooling event, the recommended device is triggered by the associated rate of change of pressure, whereas the alternate concept responds to the reduction in core pressure drop and requires calibration and adjustment by the operators to accommodate changes in reactor power.

Prevention device for rapid reactor core shutdown in BWR type reactors

International Nuclear Information System (INIS)

Koshi, Yuji; Karatsu, Hiroyuki.

1986-01-01

Purpose: To surely prevent rapid shutdown of a nuclear reactor upon partial load interruption due to rapid increase in the system frequency. Constitution: If a partial load interruption greater than the sum of the turbine by-pass valve capacity and the load setting bias portion is applied in a BWR type power plant, the amount of main steams issued from the reactor is decreased, the thermal input/output balance of the reactor is lost, the reactor pressure is increased, the void is collapsed, the neutron fluxes are increased and the reactor power rises to generate rapid reactor shutdown. In view of the above, the turbine speed signal is compared with a speed setting value in a recycling flowrate control device and the recycling pump is controlled to decrease the recycling flowrate in order to compensate the increase in the neutron fluxes accompanying the reactor power up. In this way, transient changes in the reactor core pressure and the neutron fluxes are kept within a setting point for the rapid reactor shutdown operation thereby enabling to continue the plant operation. (Horiuchi, T.)

Self-actuated shutdown system for a commercial size LMFBR. Final report

International Nuclear Information System (INIS)

Dupen, C.F.G.

1978-08-01

A Self-Actuated Shutdown System (SASS) is defined as a reactor shutdown system in which sensors, release mechanisms and neutron absorbers are contained entirely within the reactor core structure, where they respond inherently to abnormal local process conditions, by shutting down the reactor, independently of the plant protection system (PPS). It is argued that a SASS, having a response time similar to that of the PPS, would so reduce the already very low probability of a failure-to-scram event that costly design features, derived from core disruptive accident analysis, could be eliminated. However, the thrust of the report is the feasibility and reliability of the in-core SASS hardware to achieve sufficiently rapid shutdown. A number of transient overpower and transient undercooling-responsive systems were investigated leading to the selection of a primary candidate and a backup concept. During a transient undercooling event, the recommended device is triggered by the associated rate of change of pressure, whereas the alternate concept responds to the reduction in core pressure drop and requires calibration and adjustment by the operators to accommodate changes in reactor power

Site investigations, design, construction, operation, shutdown and surveillance of repositories for low- and intermediate-level radioactive wastes in rock cavities

International Nuclear Information System (INIS)

1984-01-01

The report provides an overview and technical guidelines for considerations and for activities to be undertaken for safety assessment, site investigations, design, construction, operation, shutdown and surveillance of repositories for the disposal of low- and intermediate-level radioactive wastes in rock cavities. A generalized sequence of investigations is introduced which proceeds through region and site selection to the stage where the site is confirmed by detailed geoscientific investigations as being suitable for a waste repository. The different procedures and somewhat specific investigative needs with respect to existing mines are dealt with separately. General design, as well as specific requirements with respect to the different stages of design and construction, are dealt with. A review of activities related to the operational and post-operational stages of repositories in rock cavities is presented. The report describes in general terms the procedures related to different stages of disposal operation; also the conditions for shutdown together with essential shutdown and sealing activities and the related safety assessment requirements. Guidance is also given on the surveillance programme which will allow for inspection, testing, maintenance and security of a disposal facility during the operational phase, as well as for the post-operational stage for periods determined as necessary by the national authorities

Kinetic analyses on startup and shutdown chemistry of BWR plant

International Nuclear Information System (INIS)

Domae, Masafumi; Fujiwara, Kazutoshi; Inagaki, Hiromitsu

2012-09-01

During startup and shutdown of Boiling Water Reactor (BWR) plants, temperature and dissolved oxygen (DO) concentration of reactor water change in a wide range. The changes result in variation of conductivity and pH of the reactor water. It has been speculated that the water chemistry change is due to dissolution of the oxides on fuel claddings and structural materials. However, detailed mechanism is not known. In the present paper, trend of recent water chemistry in several BWR plants during startup and shutdown is presented. Conductivity and pH are convenient indication of coolant purity. We tried to clarify the mechanism of the change in the conductivity and the pH value during startup and shutdown, based on the water chemistry data measured. In the water chemistry data, change in chromate concentration and Ni 2+ concentration is rather large. It is assumed that change in the chromate concentration and the Ni 2+ concentration results in the time variation of the conductivity and the pH value. It is reasonable to consider that the increase in the chromate concentration and the Ni 2+ concentration is ascribed to dissolution of Cr oxides and Ni oxides, respectively. A model of dissolution of the Cr oxides and the Ni oxides is proposed. A concept of finite inventory of the Cr oxides and the Ni oxides in the coolant system is introduced. The model is as follows. Chromate is generated by oxidation of the Cr oxides and the Cr dissolution rate depends on the DO concentration. The dissolution rate of chromate is in proportion to DO concentration, the inventory of Cr and difference between solubility limit and the chromate concentration. On the other hand, Ni 2+ is formed by dissolution of the Ni oxides, and DO is not necessary in this process. The dissolution rate of Ni 2+ is in proportion to the inventory of Ni and difference between solubility limit and the Ni 2+ concentration. Coolant is continuously purified, and the chromate concentration and the Ni 2+ concentration

Plant operational states analysis in low power and shutdown PSA

International Nuclear Information System (INIS)

He Jiandong; Qiu Yongping; Zhang Qinfang; An Hongzhen; Li Maolin

2013-01-01

The purpose of Plant Operational States (POS) analysis is to disperse the continuous and dynamic process of low power and shutdown operation, which is the basis of developing event tree models for accident sequence analysis. According to the design of a 300 MW Nuclear Power Plant Project, operating experience and procedures of the reference plant, a detailed POS analysis is carried out based on relative criteria. Then, several kinds of POS are obtained, and the duration of each POS is calculated according to the operation records of the reference plant. The POS analysis is an important element in low power and shutdown PSA. The methodology and contents provide reference for POS analysis. (authors)

Reactor shutdown device

Energy Technology Data Exchange (ETDEWEB)

Harada, Kiyoshi; Aono, Hidehiro [Hitachi Ltd., Tokyo (Japan); Fujita, Kaoru; Ishikawa, Tsuyoshi

1996-02-20

The present invention concerns a reactor shutdown device of a LMFBR type reactor, and provides a magnetic circuit having a sharp changing property of holding force relative to temperature change. Namely, a magnetic bridge is attached to a portion of the magnetic circuit. Then, required conditions are satisfied. Alternatively, even if the temperature dependent change of magnetic saturation of a temperature sensing alloy itself is somewhat moderated, the holding force from an erroneous dropping preventive temperature to a separating temperature can be abruptly reduced while keeping the holding force at a temperature lower than the erroneous dropping preventive temperature. Provision of the magnetic bridge increases the temperature dependent change of the holding force of the entire magnetic circuit. As a result, margin for the design of the temperature sensing alloy is extended. Actual design is enabled, and the range for selecting the temperature sensing alloy can be enlarged. (I.S.).

Reactor shutdown device

International Nuclear Information System (INIS)

Harada, Kiyoshi; Aono, Hidehiro; Fujita, Kaoru; Ishikawa, Tsuyoshi.

1996-01-01

The present invention concerns a reactor shutdown device of a LMFBR type reactor, and provides a magnetic circuit having a sharp changing property of holding force relative to temperature change. Namely, a magnetic bridge is attached to a portion of the magnetic circuit. Then, required conditions are satisfied. Alternatively, even if the temperature dependent change of magnetic saturation of a temperature sensing alloy itself is somewhat moderated, the holding force from an erroneous dropping preventive temperature to a separating temperature can be abruptly reduced while keeping the holding force at a temperature lower than the erroneous dropping preventive temperature. Provision of the magnetic bridge increases the temperature dependent change of the holding force of the entire magnetic circuit. As a result, margin for the design of the temperature sensing alloy is extended. Actual design is enabled, and the range for selecting the temperature sensing alloy can be enlarged. (I.S.)

Safe shutdown analysis for submerged equipment inside containment

International Nuclear Information System (INIS)

Song, Dong Soo; Lee, Seung Chan; Yoon, Duk Joo; Ha, Sang Jun

2017-01-01

The purpose of the paper is to analyze internal flooding effects on the submerged safety-related components inside containment building. Safe shutdown analysis has been performed based on the criteria, assumptions and guideline provided in ANSI/ANS-56.11-1988 and ANSI/ANS-58.11-1988. Flooding can be postulated from a failure of several systems located inside the containment. Loss of coolant accident (LOCA), Feed water line break (FWLB), and other pipe breaks/cracks are assumed. The worst case flooding scenario is a large break LOCA. The maximum flood level for a large break LOCA is calculated based on the combined inventory of the reactor coolant system, the three accumulators, the boron injection tank (BIT), the chemical additive tank (CAT), and the refueling water storage tank (RWST) flooding the containment. The maximum flood level that could occur from all of the water which is available in containment is 2.3 m from the base elevation. A detailed flooding analysis for the components has been performed to demonstrate that internal flooding resulting from a postulated initiating event does not cause the loss of equipment required to achieve and maintain safe shutdown of the plant, emergency core cooling capability, or equipment whose failure could result in unacceptable offsite radiological consequences. The flood height can be calculated as h = (dh/dt) x (t-t 0 ) + h 0 , where h = time dependent flood height and subscript 0 means the initial value and height slope dh/dt. In summary, the submerged components inside containment are acceptable because they complete the mission of safety injection (SI) prior to submeregency or have no safe shutdown function including containment isolation during an accident. (author)

Analysis of activation and shutdown contact dose rate for EAST neutral beam port

Science.gov (United States)

Chen, Yuqing; Wang, Ji; Zhong, Guoqiang; Li, Jun; Wang, Jinfang; Xie, Yahong; Wu, Bin; Hu, Chundong

2017-12-01

For the safe operation and maintenance of neutral beam injector (NBI), specific activity and shutdown contact dose rate of the sample material SS316 are estimated around the experimental advanced superconducting tokamak (EAST) neutral beam port. Firstly, the neutron emission intensity is calculated by TRANSP code while the neutral beam is co-injected to EAST. Secondly, the neutron activation and shutdown contact dose rates for the neutral beam sample materials SS316 are derived by the Monte Carlo code MCNP and the inventory code FISPACT-2007. The simulations indicate that the primary radioactive nuclides of SS316 are 58Co and 54Mn. The peak contact dose rate is 8.52 × 10-6 Sv/h after EAST shutdown one second. That is under the International Thermonuclear Experimental Reactor (ITER) design values 1 × 10-5 Sv/h.

Effects of shutdown chemistry on steam generator radiation levels at Point Beach Unit 2. Interim report

International Nuclear Information System (INIS)

Kormuth, J.W.

1982-05-01

A refueling shutdown chemistry test was conducted at a PWR, Point Beach Unit 2. The objective was to yield reactor coolant chemistry data during the cooldown/shutdown process which might establish a relationship between shutdown chemistry and its effects on steam generator radiation fields. Of particular concern were the effects of the presence of hydrogen in the coolant as contrasted to an oxygenated coolant. Analysis of reactor coolant samples showed a rapid soluble release (spike) in Co-58, Co-60, and nickel caused by oxygenation of the coolant. The measurement of radioisotope specific activities indicates that the material undergoing dissolution during the shutdown originated from different sources which had varying histories of activation. The test program developed no data which would support theories that oxygenation of the coolant while the steam generators are full of water contributes to increased steam generator radiation levels

Preliminary review of critical shutdown heat removal items for common cause failure susceptibility on LMFBR's. [LMFBR

Energy Technology Data Exchange (ETDEWEB)

Allard, L.T.; Elerath, J.G.

1976-02-01

This document presents a common cause failure analysis for Critical LMFBR Shutdown Heat Removal Systems. The report is intended to outline a systematic approach to defining areas with significant potential for common causes of failure, and ultimately provide inputs to the reliability prediction model. A preliminary evaluation of postulatd single initiating causes resulting in multiple failures of LMFBR-SHRS items is presented in Appendix C. This document will be periodically updated to reflect new information and activity.

A Mobile Robot for Emergency Operation of Fuel Exchange Machine

Energy Technology Data Exchange (ETDEWEB)

Seo, Yongchil; Lee, Sunguk; Kim, Changhoi; Shin, Hochul; Jung, Seungho; Choi, Changhwan [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2007-07-01

A Pressurized Heavy Water Reactor (PHWR) uses a heavy water as the coolant and moderator because it does not attenuate the neutron inside the reactor, which makes it possible to use natural uranium for nuclear fuels. However, since the uranium ratio is too low within the natural uranium, the reactor should be refueled everyday while the reactor is working. For that purpose, there is a fuel exchange machine. However as the time passes by, the durability and reliability become a problem. While the fuel handling machine exchanges the reactor fuel, it can be stuck to the pressure tube attached in the Calandra. Although this kind of situation is rarely happen, it can make the reactor be shutdown for normalizing the operation. Since the refueling is performed while the reactor is working, the radiation level is extremely high and the machine can be located at a high position up to nine meters from the floor, that is, the human worker can not approach the machine, so the fuel handling machine should be released remotely. To cope with this situation, the fuel handling machine has a manual drive mechanism at the rear side of it as shown in the circled images. If the worker can handle these manual drive mechanisms, the fuel handling machine can be released form the pressure tube. The KAERI had developed a long-reach manipulator system with a telescophic mast mechanism which can be deployed in the basement of the reactor room and manipulate the manual lever of the fuel exchange machine. Since the manipulator is located in the basement, there are several problems for its application such that the plug hole should be removed before the operation and the vibration of the mast mechanism make it difficult to locate the end effecter of the manipulator.

A Mobile Robot for Emergency Operation of Fuel Exchange Machine

International Nuclear Information System (INIS)

Seo, Yongchil; Lee, Sunguk; Kim, Changhoi; Shin, Hochul; Jung, Seungho; Choi, Changhwan

2007-01-01

A Pressurized Heavy Water Reactor (PHWR) uses a heavy water as the coolant and moderator because it does not attenuate the neutron inside the reactor, which makes it possible to use natural uranium for nuclear fuels. However, since the uranium ratio is too low within the natural uranium, the reactor should be refueled everyday while the reactor is working. For that purpose, there is a fuel exchange machine. However as the time passes by, the durability and reliability become a problem. While the fuel handling machine exchanges the reactor fuel, it can be stuck to the pressure tube attached in the Calandra. Although this kind of situation is rarely happen, it can make the reactor be shutdown for normalizing the operation. Since the refueling is performed while the reactor is working, the radiation level is extremely high and the machine can be located at a high position up to nine meters from the floor, that is, the human worker can not approach the machine, so the fuel handling machine should be released remotely. To cope with this situation, the fuel handling machine has a manual drive mechanism at the rear side of it as shown in the circled images. If the worker can handle these manual drive mechanisms, the fuel handling machine can be released form the pressure tube. The KAERI had developed a long-reach manipulator system with a telescophic mast mechanism which can be deployed in the basement of the reactor room and manipulate the manual lever of the fuel exchange machine. Since the manipulator is located in the basement, there are several problems for its application such that the plug hole should be removed before the operation and the vibration of the mast mechanism make it difficult to locate the end effecter of the manipulator

Inherently safe SNR shutdown system with Curie point controlled sensor/switch unit

International Nuclear Information System (INIS)

Mueller, K.; Norajitra, P.; Reiser, H.

1987-02-01

Inherent shutdown due to increase in the sodium temperature at the core outlet is triggered by interruption of the current supply to the electromagnet coupling of absorber elements via curie point controlled sensor/switch units. These switches are arranged above suitable fuel element positions and spatially independent of the shutdown elements. Compared with other similar systems very short response times are achieved. A prototype switch unit has already undergone extensive testing. These tests have confirmed that switching takes place in a very narrow temperature range. (orig./HP) [de

Seismic design margin evaluation of systems and equipment required for safe shutdown of North Anna, Units 1 and 2, following an SSE (safe-shutdown earthquake) event. Technical report

International Nuclear Information System (INIS)

Desai, K.D.

1981-06-01

The Advisory Committee on Reactor Safeguards recommended that the NRC staff review in detail the capability and available seismic design margin of fluid systems and equipment used in North Anna, Units 1 and 2 to achieve safe shutdown following a site-design safe-shutdown earthquake (SSE). The staff conducted a series of plant visits and meetings with the licensee to view and discuss the seismic design methodology used for systems, equipment and their supports. The report is a description and evaluation of the seismic design criteria, design conservatisms and seismic design margin for North Anna, Units 1 and 2

A public school district's vending machine policy and changes over a 4-year period: implementation of a national wellness policy.

Science.gov (United States)

Han-Markey, T L; Wang, L; Schlotterbeck, S; Jackson, E A; Gurm, R; Leidal, A; Eagle, K

2012-04-01

The school environment has been the focus of many health initiatives over the years as a means to address the childhood obesity crisis. The availability of low-nutrient, high-calorie foods and beverages to students via vending machines further exacerbates the issue of childhood obesity. However, a healthy overhaul of vending machines may also affect revenue on which schools have come to depend. This article describes the experience of one school district in changing the school environment, and the resulting impact on food and beverage vending machines. Observational study in Ann Arbor public schools. The contents and locations of vending machines were identified in 2003 and surveyed repeatedly in 2007. Overall revenues were also documented during this time period. Changes were observed in the contents of both food and beverage vending machines. Revenue in the form of commissions to the contracted companies and the school district decreased. Local and national wellness policy changes may have financial ramifications for school districts. In order to facilitate and sustain school environment change, all stakeholders, including teachers, administrators, students and healthcare providers, should collaborate and communicate on policy implementation, recognizing that change can have negative financial consequences as well as positive, healthier outcomes. Copyright © 2012 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.

Method of disposing of shut-down nuclear power plants

International Nuclear Information System (INIS)

Gaiser, H.

1984-01-01

A shut-down atomic power plant or a section thereof, particularly the nuclear reactor, is disposed of by sinking it to below ground level by constructing a caisson with cutting edges from the foundations of said plant or section or by excavating a pit therebelow

The Chernobyl plant shutdown

International Nuclear Information System (INIS)

2000-12-01

The Chernobylsk-1 reactor, operational in september 1977 has been stopped in november 1996; the Chernobylsk-2 reactor started in november 1978 is out of order since 1991 following a fire. The Chernobylsk-3 reactor began in 1981. During the last three years it occurs several maintenance operations that stop it. In june 2000, the Ukrainian authorities decided to stop it definitively on the 15. of december (2000). This file handles the subject. it is divided in four chapters: the first one gives the general context of the plant shutdown, the second chapter studies the supporting projects to stop definitively the nuclear plant, the third chapter treats the question of the sarcophagus, and the fourth and final chapter studies the consequences of the accident and the contaminated territories. (N.C.)

On the startup and shutdown of a tandem mirror reactor

International Nuclear Information System (INIS)

Chang, F.R.; DeCanio, F.T.; Fisher, J.L.; Madden, P.A.

1979-01-01

The startup and shutdown of a fusion reactor must be performed in such a way that the plasma remains MHD stable. In a tandem mirror the stability depends on a sufficiently high pressure ratio between the plugs and the central cell, of the order of 100. Control of the neutral beam input to the plugs by means of active feedback has been investigated to achieve an acceptable pressure ratio throughout the entire startup/shutdown transient. An algorithm to control the beam input power has been developed. The control law was subsequently tested in a tandem mirror simulation code. This paper describes the basic models incorporated in the simulation, as well as the derivation of the control algorithm. The simulation results are presented and the practicality of implementing the algorithm is discussed. 4 refs

Probability distribution of machining center failures

International Nuclear Information System (INIS)

Jia Yazhou; Wang Molin; Jia Zhixin

1995-01-01

Through field tracing research for 24 Chinese cutter-changeable CNC machine tools (machining centers) over a period of one year, a database of operation and maintenance for machining centers was built, the failure data was fitted to the Weibull distribution and the exponential distribution, the effectiveness was tested, and the failure distribution pattern of machining centers was found. Finally, the reliability characterizations for machining centers are proposed

Technical Meeting on Passive Shutdown Systems for Liquid Metal-Cooled Fast Reactors. Working Material

International Nuclear Information System (INIS)

2015-01-01

A major focus of the design of modern fast reactor systems is on inherent and passive safety. Specific systems to improve reactor safety performance during accidental transients have been developed in nearly all fast reactor programs, and a large number of proposed systems have reached various stages of maturity. This Technical Meeting on Passive Shutdown Systems for Fast Reactors, which was recommended by the Technical Working Group on Fast Reactors (TWG-FR), addressed Member States’ expressed need for information exchange on projects and programs in the field, as well as for the identification of priorities based on the analysis of technology gaps to be covered through R&D activities. This meeting was limited to shutdown systems only, and did not include other passive features such as natural circulation decay heat removal systems etc.; however the meeting catered to passive shutdown safety devices applicable to all types of fast neutron systems. It was agreed to initiate a new study and produce a Nuclear Energy Series (NES) Technical Report to collect information about the existing operational systems as well as innovative concepts under development. This will be a useful source for member states interested in gaining technical expertise to develop passive shutdown systems as well as to highlight the importance and development in this area

Development and study of a control and reactor shutdown device for FBR-type reactors with a modified open core

International Nuclear Information System (INIS)

Goswami, S.

1983-01-01

The doctoral thesis at hand presents a newly designed control and shutdown device to be used for output control and fast shutdown of modified open core FBR-type reactors. The task was the design of a new control and shutdown device having economic and operation advantages, using reactor components time-tested under reactor conditions. This control and shutdown device was adapted to the specific needs concerning dimensions and design. The actuation is based on the magnetic-jack principle, which has been upgraded for the purpose. The principle is now combined with pneumatic acceleration. The improvements mainly concern a smaller number of piece parts and system simplification. (orig./RW) [de

Trends vs. reactor size of passive reactivity shutdown and control performance

International Nuclear Information System (INIS)

Wade, D.C.; Fujita, E.K.

1987-01-01

For LMR concepts, the goal of passive reactivity shutdown has been approached in the US by designing the reactors for favorable relationships among the power, power/flow, and inlet temperature coefficients of reactivity, for high internal conversion ratio (yielding small burnup control swing), and for a primary pump coastdown time appropriately matched to the delayed neutron hold back of power decay upon negative reactivity input. The use of sodium bonded metallic fuel pins has facilitated the achievement of the massive shutdown design goals as a consequence of their high thermal conductivity and high effective heavy metal density. Alternately, core designs based on derated oxide pins may be able to achieve the passive shutdown features at the cost of larger core volume and increased initial fissile inventory. For LMR concepts, the passive decay heat removal goal of inherent safety has been approached in US designs by use of pool layouts, larger surface to volume ratio of the reactor vessel with natural draft air cooling of the vessel surface, elevations and redans which promote natural circulation through the core, and thermal mass of the pool contents sufficient to absorb that initial transient decay heat which exceeds the natural draft air cooling capacity. This paper describes current US ''inherently safe'' reactor design

APPLE-II type quasi-periodic variably polarizing undulator at HiSOR

International Nuclear Information System (INIS)

Sasaki, Shigemi; Miyamoto, Atsushi; Goto, Kiminori

2012-01-01

A newly constructed quasi-periodic APPLE-II undulator was installed in the HiSOR ring at Hiroshima Synchrotron Radiation Center, Hiroshima University during the summer shutdown period in 2011. This 1.8 m-long undulator has a period length of 78 mm. In this article, the mechanism of magnetic field generation for various polarization modes of APPLE undulator, the principle of quasi-periodic undulator and the performance of HiSOR QP-APPLE-II undulator are described. (author)

SNR 2 core dynamics and shut-down signals in a protected loss-of-flow incident

International Nuclear Information System (INIS)

Kleefeldt, K.

1982-01-01

The dynamic behavior of a 1300 MWe Core during a loss-of-flow incident has been analyzed by use of the SAS3D code for a given pump coast down characteristic and constant core inlet temperature. Emphasis was placed on the questions: How fast and via which monitored parameters can the incident be recognized by the reactor protection system. What is the tolerable time span for the shut-down action without exceeding safety limits. Key prameters and limit values as well as conceivable reactivity feed-back effects are discussed. The result is, that three out of four choosen monitored parameters are capable of initiating a shut-down action in time. In addition, the amount of shut-down reactivity required for a successful scram was briefly investigated

Safety and regulation aspects of nuclear facilities shutdown

International Nuclear Information System (INIS)

Clement, B.

1977-01-01

Technical dispositions that safety authorities will accept after shutdown of a nuclear installation and reglementation to use are examined. The different solutions from surveillance and maintenance, after removal of fissile materials and radioactive fluids, to dismantling are discussed especially for reactors. In each case the best solution has to be studied to ensure protection of public health and environment [fr

Oak Ridge Research reactor shutdown maintenance and surveillance

International Nuclear Information System (INIS)

Coleman, G.H.; Laughlin, D.L.

1991-05-01

The Department of Energy ordered the Oak Ridge Research Reactor to be placed in permanent shutdown on July 14, 1987. The paper outlines routine maintenance activities and surveillance tests performed April through September, 1990, on the reactor instrumentation and controls, process system, and the gaseous waste filter system. Preparations are being made to transfer the facility to the Remedial Action Program. 6 tabs

Development of Abnormal Operating Strategies for Station Blackout in Shutdown Operating Mode in Pressurized Water Reactor

Energy Technology Data Exchange (ETDEWEB)

Yoon, Duk-Joo; Lee, Seung-Chan; Sung, Je-Joong; Ha, Sang-Jun [KHNP CRI, Daejeon (Korea, Republic of); Hwang, Su-Hyun [FNC Tech. Co., Yongin (Korea, Republic of)

2016-10-15

Loss of all AC power is classified as one of multiple failure accident by regulatory guide of Korean accident management program. Therefore we need develop strategies for the abnormal operating procedure both of power operating and shutdown mode. This paper developed abnormal operating guideline for loss of all AC power by analysis of accident scenario in pressurized water reactor. This paper analyzed the loss of ultimate heat sink (LOUHS) in shutdown operating mode and developed the operating strategy of the abnormal procedure. Also we performed the analysis of limiting scenarios that operator actions are not taken in shutdown LOUHS. Therefore, we verified the plant behavior and decided operator action to taken in time in order to protect the fuel of core with safety. From the analysis results of LOUHS, the fuel of core maintained without core uncovery for 73 minutes respectively for opened RCS states after the SBO occurred. Therefore, operator action for the emergency are required to take in 73 minutes for opened RCS state. Strategy is to cooldown by using spent fuel pool cooling system. This method required to change the plant design in some plant. In RCS boundary closed state, first abnormal operating strategy in shutdown LOUHS is first abnormal operating strategy in shutdown LOUHS is to remove the residual heat of core by steam dump flow and auxiliary feedwater of SG.

Evaluation of the safety margins during shutdown for NPP Krsko

International Nuclear Information System (INIS)

Bencik, V.; Sadek, S.; Bajs, T.

2004-01-01

In the paper the results of RELAP5/mod3.3 calculations of critical parameters during shutdown for NPP Krsko are presented. Conservative evaluations have been performed at NPP Krsko to determine the minimum configuration of systems required for the safe shutdown operation. Critical parameters in these evaluations are defined as the time to start of the boiling and the time of the core dry-out. In order to have better insight into the available margins, the best estimate code RELAP5/mod3.3 has been used to calculate the same parameters. The analyzed transient is the loss of the Residual Heat Removal (RHR) system, which is used to remove decay heat during shutdown conditions. Several configurations that include open and closed Reactor Coolant System (RCS) were considered in the evaluation. The RELAP5/mod3.3 analysis of the loss of the RHR system has been performed for the following cases: 1) RCS closed and water solid, 2) RCS closed and partially drained, 3) Pressurizer manway open, Steam Generator (SG) U tubes partially drained, 4) Pressurizer and SG manways open, SG U tubes completely drained, 5) Pressurizer manway open, SGs drained, SG nozzle dams installed and 6) SG nozzle dams installed, pressurizer manway open, 1 inch break at RHR pump discharge in the loop with pressurizer. Both RHR trains were assumed in operation prior to start of the transient. The maximum average steady state temperature for all analyzed cases was limited to 333 K. (author)

Role of tumor necrosis factor in flavone acetic acid-induced tumor vasculature shutdown

International Nuclear Information System (INIS)

Mahadevan, V.; Malik, S.T.; Meager, A.; Fiers, W.; Lewis, G.P.; Hart, I.R.

1990-01-01

Flavone acetic acid (FAA), a novel investigational antitumor agent, has been shown to cause early vascular shutdown in several experimental murine tumors, and this phenomenon is believed to be crucial to FAA's antitumor effects. However, the basis of this FAA-induced tumor vascular shutdown is unknown. In this study a radioactive tracer-clearance technique has been used as an objective indication of tumor blood flow to show that i.p. administered FAA induces a progressive and sustained reduction in blood flow in a colon 26 tumor growing s.c. in syngeneic mice. As early as 1 h after administration, there was a significant increase in the t1/2 clearance value for intratumorally injected 133Xe, reaching a peak at 3 h (117.3 +/- 36.4 versus 7.8 +/- 0.85 min for controls). Significant inhibition of blood flow was still apparent 48 h after a single injection of drug. This FAA-induced vascular shutdown was virtually abolished in tumor-bearing mice pretreated with an antiserum against tumor necrosis factor, while no such effect was observed in controls pretreated with nonimmune serum (t1/2 of 10.8 +/- 1.2 versus 65.6 +/- 8.0 min for controls). Furthermore, in vitro FAA was seen to induce tumor necrosis factor secretion from murine peritoneal cells and splenocytes. These studies suggest that FAA-induced tumor vascular shutdown in the colon 26 tumor is mediated by tumor necrosis factor

235U Holdup Measurement Program in support of facility shutdown

International Nuclear Information System (INIS)

Thomason, R.S.; Griffin, J.C.; Lien, O.G.; McElroy, R.D.

1991-01-01

In 1989, the Department of Energy directed shutdown of an enriched uranium processing facility at Savannah River Site. As part of the shutdown requirements, deinventory and cleanout of process equipment and nondestructive measurement of the remaining 235 U holdup were required. The holdup measurements had safeguards, accountability, and nuclear criticality safety significance; therefore, a technically defensible and well-documented holdup measurement program was needed. Appropriate standards were fabricated, measurement techniques were selected, and an aggressive schedule was followed. Early in the program, offsite experts reviewed the measurement program, and their recommendations were adopted. Contact and far-field methods were used for most measurements, but some process equipment required special attention. All holdup measurements were documented, and each report was subjected to internal peer review. Some measured values were checked against values obtained by other methods; agreement was generally good

ATLAS distributed computing operation shift teams experience during the discovery year and beginning of the long shutdown 1

International Nuclear Information System (INIS)

Sedov, Alexey; Girolamo, Alessandro Di; Negri, Guidone; Sakamoto, Hiroshi; Schovancová, Jaroslava; Smirnov, Iouri; Vartapetian, Armen; Yu, Jaehoon

2014-01-01

ATLAS Distributed Computing Operation Shifts evolve to meet new requirements. New monitoring tools as well as operational changes lead to modifications in organization of shifts. In this paper we describe the structure of shifts, the roles of different shifts in ATLAS computing grid operation, the influence of a Higgs-like particle discovery on shift operation, the achievements in monitoring and automation that allowed extra focus on the experiment priority tasks, and the influence of the Long Shutdown 1 and operational changes related to the no beam period.

National Machine Guarding Program: Part 1. Machine safeguarding practices in small metal fabrication businesses.

Science.gov (United States)

Parker, David L; Yamin, Samuel C; Brosseau, Lisa M; Xi, Min; Gordon, Robert; Most, Ivan G; Stanley, Rodney

2015-11-01

Metal fabrication workers experience high rates of traumatic occupational injuries. Machine operators in particular face high risks, often stemming from the absence or improper use of machine safeguarding or the failure to implement lockout procedures. The National Machine Guarding Program (NMGP) was a translational research initiative implemented in conjunction with two workers' compensation insures. Insurance safety consultants trained in machine guarding used standardized checklists to conduct a baseline inspection of machine-related hazards in 221 business. Safeguards at the point of operation were missing or inadequate on 33% of machines. Safeguards for other mechanical hazards were missing on 28% of machines. Older machines were both widely used and less likely than newer machines to be properly guarded. Lockout/tagout procedures were posted at only 9% of machine workstations. The NMGP demonstrates a need for improvement in many aspects of machine safety and lockout in small metal fabrication businesses. © 2015 The Authors. American Journal of Industrial Medicine published by Wiley Periodicals, Inc.

Design and analysis of shutdown mechanisms of PFBR

International Nuclear Information System (INIS)

Vijayashree, R.; Rajan Babu, V.; Puthiyavinayagam, P.; Chellapandi, P.; Chetal, S.C.

2009-01-01

Prototype Fast Breeder Reactor (PFBR) is equipped with two independent, fast acting and diverse shutdown systems. The absorber rod of the first system is called Control and Safety Rod (CSR) and that of the second system is called Diverse Safety Rod (DSR). The respective drive mechanisms are called Control and Safety Rod Drive Mechanism (CSRDM) and Diverse Safety Rod Drive Mechanism (DSRDM). The conceptual features of the Absorber Rods (ARs) and Absorber Rod Drive Mechanisms (ARDMs) are given in the figures. The functions and design specifications of the ARDMs are listed. The theoretical results of the performance of the shutdown systems during scram are presented. The design was always backed up with testing and design validation. The individual subassemblies testing and the design have proceeded side by side, the efforts finally culminated into the manufacturing of 1:1 scale prototype ARDMs and ARs. The prototypes were extensively tested in air, water and sodium to qualify them for reactor application. A companion paper in this conference gives the details of design validation by testing. This paper gives a brief account of the design of ARDMs and ARs. (author)

Analysis of shutdown and aftercooling cycles of the A-1 nuclear power plant

International Nuclear Information System (INIS)

Mueller, V.; Vopatril, M.

1977-01-01

A new concept is described of the emergency shut-down and after-cooling of the A-1 reactor based on the elimination of pressure shock and minimization of thermal shock. After-cooling is effected by all circulators which had not been defective before shut-down. During shut-down the pumps run at reduced speed. A diesel generator is used as a self-contained power supply. The after-cooling is classified into three types depending on the machinery power consumption, i.e., normal, emergency and super-emergency. The selection of the power supply and the after-cooling conditions proceeds automatically. A mathematical model is described of A-1 reactor behaviour during different accidents requiring the shut-down and after-cooling. Computer programmes are briefly indicated for the analysis of transients in the primary coolant circuit (ZVJE-73-23, SHOCK A-1), for the analysis of transients resulting from a neutron power controller failure or from a circulator failure (HAZARD), for the analysis of after-cooling processes (DENDEL), and programme SAULIS as an auxiliary programme for processing the results and for the print-out of the DENDEL programme. Steady-state parameters before the failure were found as initial conditions for the calculation of transients. The mathematical model was solved using a system of three computer programmes linked by interprogramme communication. The analysis is described of the cooperation of reactor safety circuits and of the automatic equipment for the reduction of thermal shock in the primary coolant circuit, as is the analysis of reactor accidents related to reactor control and to the safety circuits. Theoretical results are compared with experimental values obtained during the experimental A-1 reactor shut-down and after-cooling. The accuracy of the calculated value for the cooling gas temperature at the central and marginal channel outputs is -10 to +15% during the first 30 s of after-cooling. (J.P.)

Document status for 1 and 2 Kozloduy NPP decommissioning activities -Phase 'Final Shutdown'

International Nuclear Information System (INIS)

Vangev, A.; Boyadjiev, Z.

1997-01-01

Decommissioning process (D and D) is the final phase of each nuclear reactor life cycle. The first nuclear reactor generation has reached his expiration life date. Decommissioning working documentation had not been taken into account at the project and construction stage. The decommissioning activities, planning and legislation has to develop along their operation. Most of developed nuclear energetic countries have gathered good experience and have create their own decommissioning strategy. This report represents in brief an overview of different country's approaches and the Kozloduy NPP decommissioning activity intention in near future and reviews the D and D working document status for 1 and 2 Kozloduy NPP Units decommissioning. Kozloduy NPP D and D task to the moment is to plan the first stage of the decommissioning process - 'The Final Shutdown' and to prepare the working documents for the phase execution. The Final Shutdown of Kozloduy NPP - 1 is the termination of operation of the Units 1 and 2 and the electricity production cessation after their useful life exhaust. In accordance with the legal legislation in Bulgaria only the normal planned termination of operation on units 1 and 2 should be prescribed. The project results concern the initial condition of the equipment and systems, their preparation and sequence for defueling, decontamination and dismantling. A plan for activities' organization for D and D and Complex Characterization of the Site under consideration will contain the following documents: 1. Time-schedule for the sequence of activities during the stages of the Final Shutdown and Safe Enclosure preparation. Technical project for organization of work related to Final Shutdown; 2. Complex Characterization Programme for a condition investigation of the Units 1 and 2 equipment and systems. 3. Technical project for design modifications and dismantling of equipment and systems which violate the radiation and nuclear safety during the Final Shutdown

Causes of extended shutdown state of 'RA' research reactor in Vinca Institute

International Nuclear Information System (INIS)

Pesic, M.; Kolundzija, V.; Ljubenov, V.; Cupac, S.

2001-01-01

This paper describes the causes and reasons for extended shutdown state of RA research reactor in the 'Vinca' Institute of Nuclear Sciences. Technical and legal matters that led to decision to stop RA reactor operation in 1984 and further problems related to maintenance and preparation for continuation of operation are given. Influence of nuclear policy of Yugoslav government and the 'Vinca' Institute at prolongation of the reactor shutdown state, as consequence of changing of nuclear programme in the country and the world are discussed and underlined. An overview of the legislation in the field of nuclear safety and regulatory control of radiation sources and radioactive materials in Yugoslavia is presented. (author)

Probabilities of inherent shutdown of unprotected events in innovative liquid metal reactors

International Nuclear Information System (INIS)

Mueller, C.J.

1987-01-01

The uncertainty in predicting the effectiveness of inherent shutdown (ISD) in innovative designs results from three broad contributing areas of uncertainty: (1) the inability to exactly predict the frequency of ATWS events with potential to challenge the safety systems and require ISD; (2) the approximation of representing all such ATWS events by a selected set of ''generic scenarios''; and (3) the inability to exactly calculate the core response to the selected generic scenarios. In this summary, the methodology and associated results of work used to establish probabilities of failure of inherent shutdown of innovative LMRs to the unprotected loss-of-flow (LOF) accident are discussed

Post LS1 schedule

CERN Document Server

Lamont, M

2014-01-01

The scheduling limits for a typical long year taking into account technical stops, machine development, spe- cial physics runs are presented. An attempt is then made to outline a ten year post LS1 schedule taking into account the disparate requirements outlined in the previous talks in this session. The demands on the planned long shutdowns and the impact of these demands on their proposed length will be discussed. The option of using ion running as a pre-shutdown cool-down period will be addressed.

Emergency reactor shutdown device

International Nuclear Information System (INIS)

Ikehara, Morihiko.

1982-01-01

Purpose: To smoothen the emergency operation of the control rod in a BWR type reactor and to eliminate the external discharge of radioactively contaminated water. Constitution: A drain receiving tank is connected through a scram valve to the top of a cylinder which is containing a hydraulic piston connected to a trombone-shaped control rod and an accumulator is connected through another scram valve to the bottom of the cylinder. The respective scram valves are constructed to be opened by the reactor emergency shutdown signal from a reactor control system in such a manner that drain valve and a vent valve of the tank normally opened at the standby time are closed after approx. 10 seconds from the opening of the scram valves. In this manner, back pressure is not applied to the hydraulic piston at the emergency time, thereby smoothly operating the control rod. (Sikiya, K.)

Assessment of shutdown management

International Nuclear Information System (INIS)

Marion, A.

1992-01-01

Over the past several years, there has been a number of events that have occurred during nuclear plant outages. These events included losses of AC power, losses of decay heat removal capability, reductions in shutdown margin, and losses of reactor coolant system inventory. Individually, these events have not posed nor indicated an undue risk to public health and safety. Collectively however, they contributed to a perception that outage activities are not being controlled effectively. This paper reports that for many of these same reasons, events that occur during outages have also been of concern to the industry. These events can have a significant economic impact on a company in addition to their being disruptive to the conduct of an efficient outage. And while we have expended industry resources reviewing these events, we have not been fully effective at addressing the root cause of the problem

Summary of Session 5 and 6 'Long Shutdown 1'

Energy Technology Data Exchange (ETDEWEB)

Bordry, F; Foraz, K [European Organization for Nuclear Research, Geneva (Switzerland)

2012-07-01

This paper summarizes the sessions devoted to Long Shutdown 1 (LS1) in the LHC, injectors and experiments. The time frame and start date were discussed, with the main activities from powering tests prior to warm-up up to physics were presented. The session finished with a discussion on the maximum reasonable energy. (author)

Thermosyphon Phenomenon as an alternate heat sink of Shutdown Cooling System for the CANDU reactor

Energy Technology Data Exchange (ETDEWEB)

Kim, Jonghyun [GNEST, Seoul (Korea, Republic of); Lee, Kwangho; Oh, Haechol; Jun, Hwangyong [KEPRI, Taejon (Korea, Republic of)

2006-07-01

During the outage(overhaul) of the CANDU plant, there is a period when the coolant is partially drained to the reactor header level and the coolant is cooled and depressurized by Shutdown Cooling System(SDCS) other than PHTS pump. In the postulated accident of the loss of SDCS-the PHTS pump failure, the primary coolant system should be cooled by the alternate heat sink using the thermosyphon pheonomenon(TS) through the steam generator(SG) This study was aimed at verification and analyzing the core cooling ability of the TS. And the sensitivity analysis was done for the number of SGs used in the TS. As an analysis tool, RELAP5/CANDU was used.

The Shutdown Dissociation Scale (Shut-D)

Science.gov (United States)

Schalinski, Inga; Schauer, Maggie; Elbert, Thomas

2015-01-01

The evolutionary model of the defense cascade by Schauer and Elbert (2010) provides a theoretical frame for a short interview to assess problems underlying and leading to the dissociative subtype of posttraumatic stress disorder. Based on known characteristics of the defense stages “fright,” “flag,” and “faint,” we designed a structured interview to assess the vulnerability for the respective types of dissociation. Most of the scales that assess dissociative phenomena are designed as self-report questionnaires. Their items are usually selected based on more heuristic considerations rather than a theoretical model and thus include anything from minor dissociative experiences to major pathological dissociation. The shutdown dissociation scale (Shut-D) was applied in several studies in patients with a history of multiple traumatic events and different disorders that have been shown previously to be prone to symptoms of dissociation. The goal of the present investigation was to obtain psychometric characteristics of the Shut-D (including factor structure, internal consistency, retest reliability, predictive, convergent and criterion-related concurrent validity). A total population of 225 patients and 68 healthy controls were accessed. Shut-D appears to have sufficient internal reliability, excellent retest reliability, high convergent validity, and satisfactory predictive validity, while the summed score of the scale reliably separates patients with exposure to trauma (in different diagnostic groups) from healthy controls. The Shut-D is a brief structured interview for assessing the vulnerability to dissociate as a consequence of exposure to traumatic stressors. The scale demonstrates high-quality psychometric properties and may be useful for researchers and clinicians in assessing shutdown dissociation as well as in predicting the risk of dissociative responding. PMID:25976478

The Shutdown Dissociation Scale (Shut-D

Directory of Open Access Journals (Sweden)

Inga Schalinski

2015-05-01

Full Text Available The evolutionary model of the defense cascade by Schauer and Elbert (2010 provides a theoretical frame for a short interview to assess problems underlying and leading to the dissociative subtype of posttraumatic stress disorder. Based on known characteristics of the defense stages “fright,” “flag,” and “faint,” we designed a structured interview to assess the vulnerability for the respective types of dissociation. Most of the scales that assess dissociative phenomena are designed as self-report questionnaires. Their items are usually selected based on more heuristic considerations rather than a theoretical model and thus include anything from minor dissociative experiences to major pathological dissociation. The shutdown dissociation scale (Shut-D was applied in several studies in patients with a history of multiple traumatic events and different disorders that have been shown previously to be prone to symptoms of dissociation. The goal of the present investigation was to obtain psychometric characteristics of the Shut-D (including factor structure, internal consistency, retest reliability, predictive, convergent and criterion-related concurrent validity.A total population of 225 patients and 68 healthy controls were accessed. Shut-D appears to have sufficient internal reliability, excellent retest reliability, high convergent validity, and satisfactory predictive validity, while the summed score of the scale reliably separates patients with exposure to trauma (in different diagnostic groups from healthy controls.The Shut-D is a brief structured interview for assessing the vulnerability to dissociate as a consequence of exposure to traumatic stressors. The scale demonstrates high-quality psychometric properties and may be useful for researchers and clinicians in assessing shutdown dissociation as well as in predicting the risk of dissociative responding.

LHC Operation: Past and Future (1/3)

CERN Multimedia

CERN. Geneva

2013-01-01

After a successful first running period, LHC is now well into a two year shutdown for extensive consolidation. A pedagogical overview of the machine, its operating principles, its systems and underlying accelerator physics is presented. Performance past and future is discussed. (These lectures will be presented in three parts.)

Reactor shutdown device

International Nuclear Information System (INIS)

Ito, Masahiko

1990-01-01

The object of the present invention is to reliably shutdown an LMFBR type reactor upon accident of the reactor. That is, curie point magnetic member is made annular so that it can be moved between the outer circumference of an electromagnet and the position above the electromagnet. This enables to enlarge the curie point magnetic member since it is no more necessary to be inserted it in a guide tube. Accordingly, attracting force upon normal operation is increased to remarkably improve the reliability against erronerous scram, etc. Further, since a required gap is formed between the curie point magnetic member and the electromagnet and the heat of coolants is efficiently transmitted to the curie point magnetic member, rapid scram is possible. Further, a position support mechanism is disposed to a part of a control element or at the inner side of the guiding tube for urging and actuating the armature to make it protrude above the top of the guiding tube. With such a constitution, since the armature can be adsorbed without inserting the curie point magnetic member and the electromagnet guide tube, the same effect as in the case of inserting them can be obtained. (I.S.)

National machine guarding program: Part 1. Machine safeguarding practices in small metal fabrication businesses

Science.gov (United States)

Yamin, Samuel C.; Brosseau, Lisa M.; Xi, Min; Gordon, Robert; Most, Ivan G.; Stanley, Rodney

2015-01-01

Background Metal fabrication workers experience high rates of traumatic occupational injuries. Machine operators in particular face high risks, often stemming from the absence or improper use of machine safeguarding or the failure to implement lockout procedures. Methods The National Machine Guarding Program (NMGP) was a translational research initiative implemented in conjunction with two workers' compensation insures. Insurance safety consultants trained in machine guarding used standardized checklists to conduct a baseline inspection of machine‐related hazards in 221 business. Results Safeguards at the point of operation were missing or inadequate on 33% of machines. Safeguards for other mechanical hazards were missing on 28% of machines. Older machines were both widely used and less likely than newer machines to be properly guarded. Lockout/tagout procedures were posted at only 9% of machine workstations. Conclusions The NMGP demonstrates a need for improvement in many aspects of machine safety and lockout in small metal fabrication businesses. Am. J. Ind. Med. 58:1174–1183, 2015. © 2015 The Authors. American Journal of Industrial Medicine published by Wiley Periodicals, Inc. PMID:26332060

Radiochemical guidelines and process specifications for reactor shutdown: the EDF strategy

International Nuclear Information System (INIS)

Mole, D.; Wintergerst, M.; Meylogan, Th.; Rocher, A.; Sagot, M.J.; Bonelli, V.; Bonnefon, J.; Dupont, B.

2012-09-01

Changes to French nuclear regulations made in June 2006 [1.] have made it necessary for EDF to modify its ruling principles. These modifications required the restructuring of radiochemical guidelines to better reflect their impact on nuclear safety, the environment and radioprotection. In accordance with these aims, a new authoritative document has been produced. This ruling document identifies all parameters with a potential impact on nuclear safety, radiological releases to the environment and personnel dose rates. These diagnostic and control parameters have been identified for a reactor in production and for a reactor during shutdown. For parameters related to a reactor in production, some indicators are used to evaluate impacts on availability, radioprotection and the environment during shutdown and on outage and to anticipate mitigation ways. On the other side, several parameters related to the stages of shutdown were also directly evaluated in order to minimize the impacts. This paper describes the EDF methodology used to establish operational documents: radiochemical guidelines and process specifications, and includes the following: - description of monitored parameters and their associated areas of risk; - justification of target values, frequencies of inspection and the required actions for the monitored parameters. The sizing methodology is based on theoretical studies and on EDF operational experience analysis. By implementing in the operational and technical specifications requirements linked to nuclear safety, radioprotection and environment respect, EDF will benefit from an improved compromise between these areas as well as an increased focus. (authors)

Guidance of reactor operators and TSC personnel with the severe accident management guidance under shutdown and low power conditions

International Nuclear Information System (INIS)

Van Haesendonck, M.F.; Prior, R.P.

2000-01-01

The Westinghouse Owners Group Severe Accident Management Guidance (WOG SAMG) was developed between 1991 and 1994. The primary goals for severe accident management that form the basis of the WOG SAMG are to terminate any radioactive releases to the environment; to prevent failure of any containment fission product boundary and to return the plant to a controlled stable condition. The WOG SAMG is primarily a TSC tool for mitigation of low probability core damage events. The philosophy is that control room operators should remain focused on the prevention of core damage, whereas the TSC personnel should concentrate on the mitigation of the severe accident. The symptom based package is built up as a structured process for choosing appropriate actions based on actual plant conditions. No detailed knowledge of severe accident phenomena is required. The scope of the WOG SAMG is limited to severe accidents resulting from initiating events occurring during full power operation. However, a number of studies such as the EdF EPS 1300 Probabilistic Safety Assessment (PSA), the shutdown Probabilistic Risk Assessment (PRA) for Surry, the BERA shutdown PRA for Beznau, the EPRI/ Westinghouse ORAM methodology etc. have shown that the frequency of core damage (a severe accident) during shutdown and low power operation can be of the same order of magnitude as for full power operation. The at-power SAMG is viewed as the resolution of the severe accident issue. Similarly, it is expected that as shutdown PRAs mature, the final resolution of the severe accident issue will lie in SAMG for low power and shutdown operation. Therefore in resolution of this issue, Westinghouse has developed the Shutdown Severe Accident Management Guidance (SSAMG) which gives guidance for both control room and TSC personnel to mitigate a severe accident under shutdown or low power conditions. In the last few years, many LWR plants have been implementing SAMG. In the US, all plants have developed SAMG, and many

Study on the Post-Fire Safe-Shutdown Analysis for CANDU NPPs

Energy Technology Data Exchange (ETDEWEB)

Kim, In Hwan; Kim, Yun Jung; Park, Mun Hee [KHNP Central Research Institute, Daejeon (Korea, Republic of)

2015-10-15

The purpose of this paper is to study a method of the Post-Fire Safe-Shutdown Analysis in order to apply to CANDU NPPs when one group of the Safety Structures, Systems and Components(SCCs) is failed by Fire. The purpose of Fire Protection is prevention, suppression of the fire and mitigation of the effect on the Nuclear Safety. When fire takes place at the Nuclear Power Plants(NPPs), the reactor should achieve and maintain safe shut-down condition and minimize radioactive material release to an environment. The purpose of the Post-Fire SSA process is an evaluation process during a fire at NPPs. At this study, the process was conceptually adopted for control room complex of CANDU NPPs. The Core Damage Frequency of the Reactor will be evaluated more accurately if the SSA is adopted adequately at a fire.

Preliminary Evaluation of Removing Used Nuclear Fuel from Shutdown Sites

Energy Technology Data Exchange (ETDEWEB)

Maheras, Steven J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Best, Ralph E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Ross, Steven B. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Buxton, Kenneth A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); England, Jeffery L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); McConnell, Paul E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Massaro, Lawrence M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Jensen, Philip J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2015-09-30

A preliminary evaluation of removing spent nuclear fuel (SNF) from 13 shutdown nuclear power reactor sites was conducted. At these shutdown sites the nuclear power reactors have been permanently shut down and the sites have been decommissioned or are undergoing decommissioning. The shutdown sites were Maine Yankee, Yankee Rowe, Connecticut Yankee, Humboldt Bay, Big Rock Point, Rancho Seco, Trojan, La Crosse, Zion, Crystal River, Kewaunee, San Onofre, and Vermont Yankee. The evaluation was divided into four components: (1) characterization of the SNF and greater-than-Class C low-level radioactive waste (GTCC waste) inventory, (2) a description of the on-site infrastructure and conditions relevant to transportation of SNF and GTCC waste, (3) an evaluation of the near-site transportation infrastructure and experience relevant to shipping transportation casks containing SNF and GTCC waste, including identification of gaps in information, and (4) an evaluation of the actions necessary to prepare for and remove SNF and GTCC waste. Every site was found to have at least one off-site transportation mode option for removing its SNF and GTCC waste; some have multiple options. Experience removing large components during reactor decommissioning provided an important source of information used to identify the transportation mode options for the sites. Especially important in conducting the evaluation were site visits, through which information was obtained that would not have been available otherwise. Extensive photographs taken during the site visits proved to be particularly useful in documenting the current conditions at or near the sites. It is expected that additional site visits will be conducted to add to the information presented in the evaluation.

Rodded shutdown system for a nuclear reactor

International Nuclear Information System (INIS)

Golden, M.P.; Govi, A.R.

1978-01-01

A top mounted nuclear reactor diverse rodded shutdown system utilizing gas fed into a pressure bearing bellows region sealed at the upper extremity to an armature is described. The armature is attached to a neutron absorber assembly by a series of shafts and connecting means. The armature is held in an uppermost position by an electromagnet assembly or by pressurized gas in a second embodiment. Deenergizing the electromagnet assembly, or venting the pressurized gas, causes the armature to fall by the force of gravity, thereby lowering the attached absorber assembly into the reactor core

Analysis of failure dependent test, repair and shutdown strategies for redundant trains

International Nuclear Information System (INIS)

Uryasev, S.; Samanta, P.

1994-09-01

Failure-dependent testing implies a test of a redundant components (or trains) when failure of one component has been detected. The purpose of such testing is to detect any common cause failures (CCFs) of multiple components so that a corrective action such as repair or plant shutdown can be taken to reduce the residence time of multiple failures, given a failure has been detected. This type of testing focuses on reducing the conditional risk of CCFs. Formulas for calculating the conditional failure probability of a two train system with different test, repair and shutdown strategies are developed. A methodology is presented with an example calculation showing the risk-effectiveness of failure-dependent strategies for emergency diesel generators (EDGs) in nuclear power plants (NPPs)

Application of Elements of TPM Strategy for Operation Analysis of Mining Machine

Science.gov (United States)

Brodny, Jaroslaw; Tutak, Magdalena

2017-12-01

Total Productive Maintenance (TPM) strategy includes group of activities and actions in order to maintenance machines in failure-free state and without breakdowns thanks to tending limitation of failures, non-planned shutdowns, lacks and non-planned service of machines. These actions are ordered to increase effectiveness of utilization of possessed devices and machines in company. Very significant element of this strategy is connection of technical actions with changes in their perception by employees. Whereas fundamental aim of introduction this strategy is improvement of economic efficiency of enterprise. Increasing competition and necessity of reduction of production costs causes that also mining enterprises are forced to introduce this strategy. In the paper examples of use of OEE model for quantitative evaluation of selected mining devices were presented. OEE model is quantitative tool of TPM strategy and can be the base for further works connected with its introduction. OEE indicator is the product of three components which include availability and performance of the studied machine and the quality of the obtained product. The paper presents the results of the effectiveness analysis of the use of a set of mining machines included in the longwall system, which is the first and most important link in the technological line of coal production. The set of analyzed machines included the longwall shearer, armored face conveyor and cruscher. From a reliability point of view, the analyzed set of machines is a system that is characterized by the serial structure. The analysis was based on data recorded by the industrial automation system used in the mines. This method of data acquisition ensured their high credibility and a full time synchronization. Conclusions from the research and analyses should be used to reduce breakdowns, failures and unplanned downtime, increase performance and improve production quality.

25 CFR 226.28 - Shutdown, abandonment, and plugging of wells.

Science.gov (United States)

2010-04-01

... OSAGE RESERVATION LANDS FOR OIL AND GAS MINING Cessation of Operations § 226.28 Shutdown, abandonment... production of oil and/or gas has been demonstrated to the satisfaction of the Superintendent. Lessee shall... the means by which the well bore is to be protected, and the contemplated eventual disposition of the...

Medical surveillance of nuclear power plant workers during reactor shutdown using whole-body counting and excretion analysis

International Nuclear Information System (INIS)

Le Roux-Desmis, C.

1987-01-01

After a review of radioactivity basis and radiation protection principles, the various aspects of medical surveillance of nuclear power plant workers during reactor shutdown, are presented. Internal contamination incidents that happened during 1986-1987 shutdown of Paluel reactor are exposed. Internal contamination levels are evaluated using whole-body counting and radionuclide determination in feces and urine and compared with dose limits [fr

Changing nuclear plant operating limits during startup and shutdown

International Nuclear Information System (INIS)

Arnold, E.C.; Carlson, R.W.; Ray, N.K.; Roarty, D.H.

1990-01-01

During startup and shutdown operation of pressurized water reactor (PWR) nuclear power plants, a low pressure decay heat removal system is used to maintain core cooling. During these phases of operation, there are numerous operating practices and design limits to meet special and sometimes conflicting requirements unique to these operations. This paper evaluates the impact and interdependencies of recent issues on plant operation and design

Order concerning a nuclear reactor shutdown

International Nuclear Information System (INIS)

Anon.

1991-01-01

Judgment of the State Administrative Court of Baden Wuerttemberg in head notes including: The authority of the Minister-President to give general guidelines includes the right to issue single directives; in matters of prime political significance he can take measures to realize such aims. - It is no extraneous consideration for the supervisory board under atomic energy law to point out in an order concerning a nuclear reactor shutdown that the disallowed operation of a nuclear plant conflicts with the obligation of the state to provide protection and constitutes a penal offence. Further a discourse on the assignment of discretionary powers under Paragraph 19 Section 3 Clause 2 No. 3 of the Atomic Energy Law. (HSCH) [de

Low Power Shutdown PSA for CANDU Type Plants

Energy Technology Data Exchange (ETDEWEB)

Bae, Yeon Kyoung; Kim, Myung Su [KHNP CRI, Daejeon (Korea, Republic of)

2016-10-15

KHNP also have concentrated on full power PSA. Some recently constructed OPR1000 type plants and APR1400 type plants have performed the low power and shutdown (LPSD) PSA. The purpose of LPSD PSA is to identify the main contributors on the accident sequences of core damage and to find the measure of safety improvement. After the Fukushima accident, Korean regulatory agency required the shutdown severe accident management guidelines (SSAMG) development for safety enhancement. For the reliability of SSAMG, KHNP should develop the LPSD PSA. Especially, the LPSD PSA for CANDU type plant had developed for the first time in Korea. This paper illustrates how the LPSD PSA for CANDU type developed and the core damage frequency (CDF) is different with that of full power PSA. KHNP performed LPSD PSA to develop the SSAMG after the Fukushima accidents. The results show that risk at the specific operation mode during outage is higher than that of full power operation. Also, the results indicated that recovery failure of class 4 power at the POS 5A, 5B contribute dominantly to the total CDF from importances analysis. LPSD PSA results such as CDF with initiating events and POSs, risk results with plant damage state, and containment failure probability and frequency with POSs can be used by inputs for developing the SSAMG.

Runaway electron generation during plasma shutdown by killer pellet injection

International Nuclear Information System (INIS)

Gal, K; Feher, T; Smith, H; Fueloep, T; Helander, P

2008-01-01

Tokamak discharges are sometimes terminated by disruptions that may cause large mechanical and thermal loads on the vessel. To mitigate disruption-induced problems it has been proposed that 'killer' pellets could be injected into the plasma in order to safely terminate the discharge. Killer pellets enhance radiative energy loss and thereby lead to rapid cooling and shutdown of the discharge. But pellets may also cause runaway electron generation, as has been observed in experiments in several tokamaks. In this work, runaway dynamics in connection with deuterium or carbon pellet-induced fast plasma shutdown is considered. A pellet code, which calculates the material deposition and initial cooling caused by the pellet is coupled to a runaway code, which determines the subsequent temperature evolution and runaway generation. In this way, a tool has been created to test the suitability of different pellet injection scenarios for disruption mitigation. If runaway generation is avoided, the resulting current quench times are too long to safely avoid large forces on the vessel due to halo currents

Report of a consultants meeting on accidents during shutdown conditions for WWER nuclear power plants. Extrabudgetary programme on the safety of WWER NPPs

International Nuclear Information System (INIS)

1996-07-01

The main objectives of the meeting were to exchange information on the operational occurrences, studies performed and countermeasures taken for the accidents during shutdown for WWERs, and to define the necessity and directions of the further activities which may promote the improvement of WWER safety under shutdown conditions. The consultants have discussed some aspects concerning vulnerability of safety functions during shutdown conditions, several steps required to performed accident analysis and selected operational aspects for shutdown conditions. The discussion was supported by an evaluation of selected operational occurrences. The consultants have agreed that the discussion during the meeting in major parts is relevant to all the WWER designs (i.e. WWER-1000, WWER-440/213 and WWER-440/230). As for the plant conditions, the consultants have agreed to bound the discussion mainly by the cold shutdown and refuelling modes. Refs, figs, tabs

Reactor shut-down device

International Nuclear Information System (INIS)

Otsuka, Fumio; Horikawa, Yuji.

1990-01-01

The present invention concerns an externally disposed reactor shut-down device for an FBR type reactor using liquid sodium as coolants. An introducing pipe having an outlet port disposed at an upper portion thereof is disposed at a lower end of an upper guide tube. An extension tube, an L-shaped measuring wire support and a measuring wire are disposed at the inside of the guide tube. With such a constitution, low temperature coolants flown out from the lower guide tube of a control rod and a great amount of high temperature coolants flown out from the lower guide tube of a fuel assembly are introduced smoothly to the introducing tube having the measuring wire support disposed therein. Accordingly, the high temperature coolants can be prevented from flowing out to the outside of the introducing tube and coolants after mixing can be flown and hit against a curie point electromagnet efficiently. This can make the response to abnormal temperature rise of coolants satisfactory and can provide reliable reactor scram. (I.N.)

Advances in the physics modelling of CANDU liquid injection shutdown systems

International Nuclear Information System (INIS)

Smith, H.J.; Robinson, R.; Guertin, C.

1993-01-01

The physics modelling of liquid poison injection shutdown systems in CANDU reactors accounts for the major phenomena taking place by combining the effects of both moderator hydraulics and neutronics. This paper describes the advances in the physics modelling of liquid poison injection shutdown systems (LISS), discusses some of the effects of the more realistic modelling, and briefly describes the automation methodology. Modifications to the LISS methodology have improved the realism of the physics modelling, showing that the previous methodology significantly overestimated energy deposition during the simulation of a loss of coolant transient in Bruce A, by overestimating the reactivity transient. Furthermore, the automation of the modelling process has reduced the time needed to carry put LISS evaluations to the same level as required for shutoff-rod evaluations, while at the same time minimizing the amount of input, and providing a method for tracing all files used, thus adding a level of quality assurance to the calculation. 5 refs., 11 figs

Experimental and analytical studies of a passive shutdown heat removal system for advanced LMRs

International Nuclear Information System (INIS)

Heineman, J.; Kraimer, M.; Lottes, P.; Pedersen, D.; Stewart, R.; Tessier, J.

1988-01-01

A facility designed and constructed to demonstrate the viability of natural convection passive heat removal systems as a key feature of innovative LMR Shutdown Heat Removal (SHR) systems is in operation at Argonne National Laboratory (ANL). This Natural Convection Shutdown Heat Removal Test Facility (NSTF) is being used to investigate the heat transfer performance of the GE/PRISM and the RI/SAFR passive designs. This paper presents a description of the NSTF, the pretest analysis of the Radiant Reactor Vessel Auxiliary Cooling System (RVACS) in support of the GE/PRISM IFR concept, and experiment results for the RVACS simulation. Preliminary results show excellent agreement with predicted system performance

Evaluation of induced activity, decay heat and dose rate distribution after shutdown in ITER

Energy Technology Data Exchange (ETDEWEB)

Maki, Koichi [Hitachi Ltd., Ibaraki (Japan). Hitachi Research Lab.; Satoh, Satoshi; Hayashi, Katsumi; Yamada, Koubun; Takatsu, Hideyuki; Iida, Hiromasa

1997-03-01

Induced activity, decay heat and dose rate distributions after shutdown were estimated for 1MWa/m{sup 2} operation in ITER. The activity in the inboard blanket one day after shutdown is 1.5x10{sup 11}Bq/cm{sup 3}, and the average decay heating rate 0.01w/cm{sup 3}. The dose rate outside the 120cm thick concrete biological shield is two order higher than the design criterion of 5{mu}Sv/h. This indicates that the biological shield thickness should be enhanced by 50cm in concrete, that is, total thickness 170cm for workers to enter the reactor room and to perform maintenance. (author)

Experimental and analytical studies of a passive shutdown heat removal system for advanced LMRs

Energy Technology Data Exchange (ETDEWEB)

Heineman, J.; Kraimer, M.; Lottes, P.; Pedersen, D.; Stewart, R.; Tessier, J.

1988-01-01

A facility designed and constructed to demonstrate the viability of natural convection passive heat removal systems as a key feature of innovative LMR Shutdown Heat Removal (SHR) systems is in operation at Argonne National Laboratory (ANL). This Natural Convection Shutdown Heat Removal Test Facility (NSTF) is being used to investigate the heat transfer performance of the GE/PRISM and the RI/SAFR passive designs. This paper presents a description of the NSTF, the pretest analysis of the Radiant Reactor Vessel Auxiliary Cooling System (RVACS) in support of the GE/PRISM IFR concept, and experiment results for the RVACS simulation. Preliminary results show excellent agreement with predicted system performance.

LHC Detector Vacuum System Consolidation for Long Shutdown 1 (LS1) in 2013-2014

CERN Document Server

Gallilee, M; Cruikshank, P; Gallagher, J; Garion, C; Jimenez, J M; Kersevan, R; Kos, H; Leduc, L; Lepeule, P; Provot, N; Rambeau, H; Veness, R

2012-01-01

The LHC has ventured into unchartered territory for Particle Physics accelerators. A dedicated consolidation program is required between 2013 and 2014 to ensure optimal physics performance. The experiments, ALICE, ATLAS, CMS, and LHCb, will utilise this shutdown, along with the gained experience of three years of physics running, to make optimisations to their detectors. New vacuum technologies have been developed for the experimental areas, to be integrated during this first phase shutdown. These technologies include bellows, vacuum chambers and ion pumps in aluminium, new beryllium vacuum chambers, and composite mechanical supports. An overview of this first phase consolidation program for the LHC experiments is presented.

Historical and Epistemological Reflections on the Culture of Machines around the Renaissance: Machines, Machineries and Perpetual Motion

Directory of Open Access Journals (Sweden)

Raffaele Pisano

2015-05-01

Full Text Available This paper is the second part of our recent paper ‘Historical and Epistemological Reflections on the Culture of Machines around the Renaissance: How Science and Technique Work’ (Pisano & Bussotti 2014a. In the first paper—which discussed some aspects of the relations between science and technology from Antiquity to the Renaissance—we highlighted the differences between the Aristotelian/Euclidean tradition and the Archimedean tradition. We also pointed out the way in which the two traditions were perceived around the Renaissance. The Archimedean tradition is connected with machines: its relationship with science and construction of machines should be made clear. It is enough to think that Archimedes mainly dealt with three machines: lever, pulley and screw (and a correlated principle of mechanical advantage. As underlined in the first part, our thesis is that many machines were constructed by people who ignored theory, even though, in other cases, the knowledge of the Archimedean tradition was a precious help in order to build machines. Hence, an a priori idea as to the relations between the Archimedean tradition and construction of machines cannot exist. In this second part we offer some examples of functioning machines constructed by people who ignored any physical theory, whereas, in other cases, the ignorance of some principles—such as the impossibility of a perpetuum mobile—induced the attempt to construct impossible machines. What is very interesting is that these machines did not function, of course, as a perpetuum mobile, but anyway had their functioning and were useful for certain aims, although they were constructed on an idea which is completely wrong from a theoretical point of view. We mainly focus on the Renaissance and early modern period, but we also provide examples of machines built before and after this period. We have followed a chronological order in both parts, starting from the analysis of the situation in

Outcomes of an international initiative for harmonization of low power and shutdown probabilistic safety assessment

Directory of Open Access Journals (Sweden)

Manna Giustino

2010-01-01

Full Text Available Many probabilistic safety assessment studies completed to the date have demonstrated that the risk dealing with low power and shutdown operation of nuclear power plants is often comparable with the risk of at-power operation, and the main contributors to the low power and shutdown risk often deal with human factors. Since the beginning of the nuclear power generation, human performance has been a very important factor in all phases of the plant lifecycle: design, commissioning, operation, maintenance, surveillance, modification, decommissioning and dismantling. The importance of this aspect has been confirmed by recent operating experience. This paper provides the insights and conclusions of a workshop organized in 2007 by the IAEA and the Joint Research Centre of the European Commission, on Harmonization of low power and shutdown probabilistic safety assessment for WWER nuclear power plants. The major objective of the workshop was to provide a comparison of the approaches and the results of human reliability analyses and gain insights in the enhanced handling of human factors.

Development and validation of the shutdown cooling system CATHENA model for Gentilly-2

International Nuclear Information System (INIS)

Lecuyer, H.; Hasnaoui, C.; Sabourin, G.; Chapados, S.

2008-01-01

A CATHENA representation of the Gentilly-2 Shutdown Cooling system has been developed for Hydro-Quebec. The model includes the SDCS circuit piping, valves, pumps and heat exchangers. The model is integrated in the G2 CATHENA overall plant model and coupled with the plant control software simulator TROLG2 to allow the simulation of various plant operational modes using the SDCS. Results have been obtained for normal cooling of the primary heat transport system following a planned shut down (transition from full power to shutdown) and for two special SDCS configurations that were used on September 14 and 15, 2006 at Gentilly-2. The results show close match with values measured at Gentilly-2 during either steady or transient states. (author)

Development and validation of the shutdown cooling system CATHENA model for Gentilly-2

Energy Technology Data Exchange (ETDEWEB)

Lecuyer, H.; Hasnaoui, C. [Nucleonex Inc., Westmount, Quebec (Canada); Sabourin, G. [Atomic Energy of Canada Limited, Montreal, Quebec (Canada); Chapados, S. [Hydro-Quebec, Unite Analyse et Fiabilite, Montreal, Quebec (Canada)

2008-07-01

A CATHENA representation of the Gentilly-2 Shutdown Cooling system has been developed for Hydro-Quebec. The model includes the SDCS circuit piping, valves, pumps and heat exchangers. The model is integrated in the G2 CATHENA overall plant model and coupled with the plant control software simulator TROLG2 to allow the simulation of various plant operational modes using the SDCS. Results have been obtained for normal cooling of the primary heat transport system following a planned shut down (transition from full power to shutdown) and for two special SDCS configurations that were used on September 14 and 15, 2006 at Gentilly-2. The results show close match with values measured at Gentilly-2 during either steady or transient states. (author)

Automated valve fault detection based on acoustic emission parameters and support vector machine

Directory of Open Access Journals (Sweden)

Salah M. Ali

2018-03-01

Full Text Available Reciprocating compressors are one of the most used types of compressors with wide applications in industry. The most common failure in reciprocating compressors is always related to the valves. Therefore, a reliable condition monitoring method is required to avoid the unplanned shutdown in this category of machines. Acoustic emission (AE technique is one of the effective recent methods in the field of valve condition monitoring. However, a major challenge is related to the analysis of AE signal which perhaps only depends on the experience and knowledge of technicians. This paper proposes automated fault detection method using support vector machine (SVM and AE parameters in an attempt to reduce human intervention in the process. Experiments were conducted on a single stage reciprocating air compressor by combining healthy and faulty valve conditions to acquire the AE signals. Valve functioning was identified through AE waveform analysis. SVM faults detection model was subsequently devised and validated based on training and testing samples respectively. The results demonstrated automatic valve fault detection model with accuracy exceeding 98%. It is believed that valve faults can be detected efficiently without human intervention by employing the proposed model for a single stage reciprocating compressor. Keywords: Condition monitoring, Faults detection, Signal analysis, Acoustic emission, Support vector machine

Estimation of shutdown heat generation rates in GHARR-1 due to ...

African Journals Online (AJOL)

Fission products decay power and residual fission power generated after shutdown of Ghana Research Reactor-1 (GHARR-1) by reactivity insertion accident were estimated by solution of the decay and residual heat equations. A Matlab program code was developed to simulate the heat generation rates by fission product ...

Discrete time analysis of a repairable machine

OpenAIRE

Alfa, Attahiru Sule; Castro, I. T.

2002-01-01

We consider, in discrete time, a single machine system that operates for a period of time represented by a general distribution. This machine is subject to failures during operations and the occurrence of these failures depends on how many times the machine has previously failed. Some failures are repairable and the repair times may or may not depend on the number of times the machine was previously repaired. Repair times also have a general distribution. The operating times...

Passive shut-down of ITER plasma by Be evaporation

International Nuclear Information System (INIS)

Amano, Tsuneo.

1996-02-01

In an accident event where the cooling system of first wall of the ITER fails, the first wall temperature continues to rise as long as the ignited state of the core plasma persists. In this paper, a passive shut-down scheme of the ITER from this accident by evaporated Be from the first wall is examined. It is shown the estimated Be influx 5 10 24 /sec is sufficient to quench the ignition. (author)

Small leak shutdown, location, and behavior in LMFBR steam generators

International Nuclear Information System (INIS)

Sandusky, D.W.

1976-01-01

The paper summarizes an experimental study of small leaks tested under LMFBR steam generator conditions. Defected tubes were exposed to flowing sodium and steam. The observed behavior of the defected tubes is reported along with test results of shutdown methods. Leak location methods were investigated. Methods were identified to open plugged defects for helium leak testing and detect plugged leaks by nondestructive testing

Dynamic Analysis of a Floating Vertical Axis Wind Turbine Under Emergency Shutdown Using Hydrodynamic Brake

DEFF Research Database (Denmark)

Wang, K.; Hansen, Martin Otto Laver; Moan, T.

2014-01-01

Emergency shutdown is always a challenge for an operating vertical axis wind turbine. A 5-MW vertical axis wind turbine with a Darrieus rotor mounted on a semi-submersible support structure was examined in this study. Coupled non-linear aero-hydro-servo-elastic simulations of the floating vertical...... axis wind turbine were carried out for emergency shutdown cases over a range of environmental conditions based on correlated wind and wave data. When generator failure happens, a brake should be applied to stop the acceleration of the rotor to prevent the rotor from overspeeding and subsequent disaster...

Impact of Government Shutdown on Child Care and Early Education Programs

Science.gov (United States)

Center for Law and Social Policy, Inc. (CLASP), 2013

2013-01-01

Congress did not enact a continuing resolution bill by midnight September 30, 2013, thereby triggering a partial government shutdown effective October 1, 2013. October 1 began the federal fiscal year 2014. Most discretionary programs, those that are subject to the annual Congressional appropriations process, will not receive 2014 funding. Most,…

Ultrasonic measurement of gap between calandria tube and liquid injection shutdown system tube in PHWR

International Nuclear Information System (INIS)

Kim, Tae Ryong; Sohn, Seok Man; Lee, Jun Shin; Lee, Sun Ki; Lee, Jong Po

2001-01-01

Sag of CT or liquid injection shutdown system tubes in pressurized heavy water reactor is known to occur due to irradiation creep and growth during plant operation. When the sag of CT is big enough, the CT tube possibly comes in contact with liquid injection shutdown system tube (LIN) crossing beneath the CT, which subsequently may prevent the safe operation. It is therefore necessary to check the gap between the two tubes in order to confirm no contacts when using a proper measure periodically during the plant life. An ultrasonic gap measuring probe assembly which can be fed through viewing port installed on the calandria was developed and utilized to measure the sags of both tubes in a pressurized heavy water reactor in Korea. It was found that the centerlines of CT and LIN can be precisely detected by ultrasonic wave. The gaps between two tubes were easily obtained from the relative distance of the measured centerline elevations of the tubes. But the measured gap data observed at the viewing port were actually not the data at the crossing point of CT and LIN. To get the actual gap between two tubes, mathematical modeling for the deflection curves of two tubes was used. The sags of CT and LIN tubes were also obtained by comparison of the present centerlines with the initial elevations at the beginning of plant operation. The gaps between two tubes in the unmeasurable regions were calculated based on the measurement data and the channel power distribution

Potential improvement of CANDU NPP safety margins by shortening the response time of shutdown systems using FPGA based implementation

Energy Technology Data Exchange (ETDEWEB)

Jingke She, E-mail: jshe2@uwo.ca [Department of Electrical and Computer Engineering, University of Western Ontario, London, Ontario N6A 5B9 (Canada); Jin Jiang, E-mail: jjiang@eng.uwo.ca [Department of Electrical and Computer Engineering, University of Western Ontario, London, Ontario N6A 5B9 (Canada)

2012-03-15

Highlights: Black-Right-Pointing-Pointer Quantitative analysis of the safety margin improvement through thermalhydraulic simulation and analysis. Black-Right-Pointing-Pointer Hardware-in-the-loop simulation of realizing the improvement by an FPGA-based SDS1. Black-Right-Pointing-Pointer Verification of potential operating power upgrade without endangering the plant safety. - Abstract: The relationship between the peak values of critical reactor variables, such as neutronic power, inside a CANDU reactor and the speed of the response of its shutdown system has been analyzed in the event of a large loss of coolant accident (LOCA). The advantage of shortening the response time of the shutdown action has been demonstrated in term of the improved safety margin. A field programmable gate array (FPGA) platform has been chosen to implement such a shutdown system. Hardware-in-the-loop (HIL) simulations have been performed to demonstrate the feasibility of this concept. Furthermore, connections between the speed of response of the shutdown system and the nominal operating power level of the reactor have been drawn to support for potential power upgrade for existing power plants.

Hazard Classification for Fuel Supply Shutdown Facility

International Nuclear Information System (INIS)

BENECKE, M.W.

2000-01-01

Final hazard classification for the 300 Area N Reactor fuel storage facility resulted in the assignment of Nuclear Facility Hazard Category 3 for the uranium metal fuel and feed material storage buildings (303-A, 303-B, 303-G, 3712, and 3716). Radiological for the residual uranium and thorium oxide storage building and an empty former fuel storage building that may be used for limited radioactive material storage in the future (303-K/3707-G, and 303-E), and Industrial for the remainder of the Fuel Supply Shutdown buildings (303-F/311 Tank Farm, 303-M, 313-S, 333, 334 and Tank Farm, 334-A, and MO-052)

Technical Assessment: WRAP 1 HVAC Passive Shutdown

International Nuclear Information System (INIS)

Ball, D.E.; Nash, C.R.; Stroup, J.L.

1993-01-01

As the result of careful interpretation of DOE Order 6430.lA and other DOE Orders, the HVAC system for WRAP 1 has been greatly simplified. The HVAC system is now designed to safely shut down to Passive State if power fails for any reason. The fans cease functioning, allowing the Zone 1 and Zone 2 HVAC Confinement Systems to breathe with respect to atmospheric pressure changes. Simplifying the HVAC system avoided overdesign. Construction costs were reduced by eliminating unnecessary equipment. This report summarizes work that was done to define the criteria, physical concepts, and operational experiences that lead to the passive shutdown design for WRAP 1 confinement HVAC systems

Program of social protection for Chornobyl nuclear power plant staff and Slavutich town residents in the aftermath of the plant shutdown

International Nuclear Information System (INIS)

Komarov, V.A.

2001-01-01

In order to solve social issues related to ChNPP shutdown, the Ukrainian Government approved 'Program of Social Protection for Chornobyl Nuclear Power Plant Staff and Slavutich Town Residents in Aftermath of Plant Shutdown' on 29 November 2000. The Program Objective is to ensure social protection and support of well being of ChNPP staff and Slavutich town residents after the plant shutdown. Preserve and develop town infrastructure. Create compensatory jobs; efficiently manage human resources; provide social allowances and guarantees to the ChNPP staff that is being released, and Slavutich town residents

Uncertainty evaluation of reliability of shutdown system of a medium size fast breeder reactor

Energy Technology Data Exchange (ETDEWEB)

Zeliang, Chireuding; Singh, Om Pal, E-mail: singhop@iitk.ac.in; Munshi, Prabhat

2016-11-15

Highlights: • Uncertainty analysis of reliability of Shutdown System is carried out. • Monte Carlo method of sampling is used. • The effect of various reliability improvement measures of SDS are accounted. - Abstract: In this paper, results are presented on the uncertainty evaluation of the reliability of Shutdown System (SDS) of a Medium Size Fast Breeder Reactor (MSFBR). The reliability analysis results are of Kumar et al. (2005). The failure rate of the components of SDS are taken from International literature and it is assumed that these follow log-normal distribution. Fault tree method is employed to propagate the uncertainty in failure rate from components level to shutdown system level. The beta factor model is used to account different extent of diversity. The Monte Carlo sampling technique is used for the analysis. The results of uncertainty analysis are presented in terms of the probability density function, cumulative distribution function, mean, variance, percentile values, confidence intervals, etc. It is observed that the spread in the probability distribution of SDS failure rate is less than SDS components failure rate and ninety percent values of the failure rate of SDS falls below the target value. As generic values of failure rates are used, sensitivity analysis is performed with respect to failure rate of control and safety rods and beta factor. It is discovered that a large increase in failure rate of SDS rods is not carried to SDS system failure proportionately. The failure rate of SDS is very sensitive to the beta factor of common cause failure between the two systems of SDS. The results of the study provide insight in the propagation of uncertainty in the failure rate of SDS components to failure rate of shutdown system.

Oak Ridge Research Reactor shutdown maintenance and surveillance

International Nuclear Information System (INIS)

Coleman, G.H.; Laughlin, D.L.

1990-10-01

The Department of Energy ordered the Oak Ridge Research Center Reactor to be placed in permanent shutdown on July 14, 1987. Maintenance activities, both mechanical and instrument, were essentially routine in nature. The performance of the instrumentation for the facility was satisfactory, and maintenance required is provided. The performance of the process system was satisfactory, and maintenance required is indicated. The results of efficiency tests of the various gaseous-waste filters have been summarized and preparations for transfer of the facility to the remedial action program is also indicated

0-d modeling of fast radiative shutdown of Tokamak discharges following massive gas injection

International Nuclear Information System (INIS)

Hollmann, E.M.; Parks, P.B.; Scott, H.A.

2008-01-01

0-D modeling of fast radiative shutdowns of tokamak discharges following massive gas injection is presented. Realistic neutral deposition rates are used together with a 1-D diffusive model to estimate impurity deposition into the plasma. Non-coronal radiation rates including opacity are used, as are induced wall currents, wall impurity radiation, and neutral and neoclassical corrections to plasma resistivity. The 0-D modeling is found to reproduce the shutdown timescale and free electron density rise seen in DIII-D argon injection experiments well. Opacity, wall currents, and wall impurities can all have a significant (>10%) impact on simulated timescales. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Long-period maintenance program of JRR-3M

International Nuclear Information System (INIS)

Murayama, Yoji; Onozaki, Michio; Kakefuda, Kazuhiro

1999-01-01

The JRR-3M is a swimming pool type research reactor with maximum thermal output of 20 MW, classed in a large-scale research reactor and composed of numerous facilities. An operation cycle consists of 4 weeks of continuously reactor operation and 1 week of shutdown work such as fuel exchange and irradiation sample handling. The temporary and small-scale maintenance is also carried out during the shutdown period. Systematic maintenance period through a year usually follows 2 stages. The former stage of about 4 weeks is prepared to maintain the general facilities related to the overall reactor system such as computer system. The latter stage of about 9 weeks is prepared to maintain the other individual facilities such as cooling facilities and control facilities that are to be inspected by the regulatory body. Since preventive maintenance is required in order to achieve an improvement of safety, reliability and availability throughout the life cycle of the reactor, a long-period maintenance program should be prepared properly in consideration of an ageing degradation of the facilities. The long-period maintenance program of JRR-3M, which determines not only the replacement frequency but also the maintenance frequency of the facilities, is made on the basis of an ageing degradation of the facilities, irradiation effects of the materials, recommendations from the manufacturer and JRR-3M maintenance records. The replacement frequency recommended by the manufacturer is examined from the viewpoint of the safety significance of the facilities and availability of the components. The program is arranged so that it may not concentrate the replacement of the facilities in the specific fiscal year and smooth the budget and maintenance period throughout the life cycle of the reactor. There have been two unanticipated failures of the facilities, which required rearranging the program. (author)

Periodic feedback stabilization for linear periodic evolution equations

CERN Document Server

Wang, Gengsheng

2016-01-01

This book introduces a number of recent advances regarding periodic feedback stabilization for linear and time periodic evolution equations. First, it presents selected connections between linear quadratic optimal control theory and feedback stabilization theory for linear periodic evolution equations. Secondly, it identifies several criteria for the periodic feedback stabilization from the perspective of geometry, algebra and analyses respectively. Next, it describes several ways to design periodic feedback laws. Lastly, the book introduces readers to key methods for designing the control machines. Given its coverage and scope, it offers a helpful guide for graduate students and researchers in the areas of control theory and applied mathematics.

A Study on the Risk Reduction Effect by MLCS (Mid-loop Level Control System) of EUAPR using the Low-Power and Shutdown PSA Result

International Nuclear Information System (INIS)

Lee, Keunsung; Choi, Sunmi; Kim, Eden

2016-01-01

The EU-APR design has been developed in order to expand and diversify the global nuclear power market of APR1400. For the improvement of shutdown risk for the EUAPR, the mid-loop level control system (MLCS) is considered during mid-loop operation for the EU-APR, which is not incorporated into SKN 3 and 4 (APR1400 Type) in Korea. Commonly, the risk associated with the NPP can be identified through the PSA. Thus, this paper discusses the low power and shutdown (LPSD) risk reduction effect by MLCS using the Low-Power and Shutdown PSA Result. LPSD level 1 PSA models for EU-APR have been developed. The risk reduction effect by MLCS is discussed. Because the loss of shutdown cooling function during mid-loop is one of the most vulnerable events, the MLCS have a significant influence on CDF in LPSD PSA. The shutdown risk of domestic power plants would likely be reduced if the MLCS is adopted in all operating NPPs in Korea during the mid-loop operation. It is expected that this work will contribute to reduce shutdown risk of domestic power plants

Reinforcement and Systemic Machine Learning for Decision Making

CERN Document Server

Kulkarni, Parag

2012-01-01

Reinforcement and Systemic Machine Learning for Decision Making There are always difficulties in making machines that learn from experience. Complete information is not always available-or it becomes available in bits and pieces over a period of time. With respect to systemic learning, there is a need to understand the impact of decisions and actions on a system over that period of time. This book takes a holistic approach to addressing that need and presents a new paradigm-creating new learning applications and, ultimately, more intelligent machines. The first book of its kind in this new an

46 CFR 32.50-35 - Remote manual shutdown for internal combustion engine driven cargo pump on tank vessels-TB/ALL.

Science.gov (United States)

2010-10-01

... 46 Shipping 1 2010-10-01 2010-10-01 false Remote manual shutdown for internal combustion engine... for Cargo Handling § 32.50-35 Remote manual shutdown for internal combustion engine driven cargo pump on tank vessels—TB/ALL. (a) Any tank vessel which is equipped with an internal combustion engine...

Periodicity and Immortality in Reversible Computing

OpenAIRE

Kari , Jarkko; Ollinger , Nicolas

2008-01-01

Additional material available on the web at http://www.lif.univ-mrs.fr/~nollinge/rec/gnirut/; We investigate the decidability of the periodicity and the immortality problems in three models of reversible computation: reversible counter machines, reversible Turing machines and reversible one-dimensional cellular automata. Immortality and periodicity are properties that describe the behavior of the model starting from arbitrary initial configurations: immortality is the property of having at le...

Despite the Shutdown, Rescheduled NIH Research Festival Brings Science to the Forefront | Poster

Science.gov (United States)

By Andrea Frydl, Contributing Writer Although it was delayed by almost a month because of the federal shutdown, the NIH Research Festival still took place at the NIH Clinical Center in Bethesda, Md., and attendance was high.

Non-equilibrium quantum heat machines

Science.gov (United States)

Alicki, Robert; Gelbwaser-Klimovsky, David

2015-11-01

Standard heat machines (engine, heat pump, refrigerator) are composed of a system (working fluid) coupled to at least two equilibrium baths at different temperatures and periodically driven by an external device (piston or rotor) sometimes called the work reservoir. The aim of this paper is to go beyond this scheme by considering environments which are stationary but cannot be decomposed into a few baths at thermal equilibrium. Such situations are important, for example in solar cells, chemical machines in biology, various realizations of laser cooling or nanoscopic machines driven by laser radiation. We classify non-equilibrium baths depending on their thermodynamic behavior and show that the efficiency of heat machines powered by them is limited by the generalized Carnot bound.

Non-equilibrium quantum heat machines

International Nuclear Information System (INIS)

Alicki, Robert; Gelbwaser-Klimovsky, David

2015-01-01

Standard heat machines (engine, heat pump, refrigerator) are composed of a system (working fluid) coupled to at least two equilibrium baths at different temperatures and periodically driven by an external device (piston or rotor) sometimes called the work reservoir. The aim of this paper is to go beyond this scheme by considering environments which are stationary but cannot be decomposed into a few baths at thermal equilibrium. Such situations are important, for example in solar cells, chemical machines in biology, various realizations of laser cooling or nanoscopic machines driven by laser radiation. We classify non-equilibrium baths depending on their thermodynamic behavior and show that the efficiency of heat machines powered by them is limited by the generalized Carnot bound. (paper)

Enhancing Efficiency of Safeguards at Facilities that are Shutdown or Closed-Down, including those being Decommissioned

Energy Technology Data Exchange (ETDEWEB)

Moran, B. [Brookhaven National Lab. (BNL), Upton, NY (United States); Stern, W. [Brookhaven National Lab. (BNL), Upton, NY (United States); Colley, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Marzo, M. [Brookhaven National Lab. (BNL), Upton, NY (United States)

2016-12-15

International Atomic Energy Agency (IAEA) safeguards involves verification activities at a wide range of facilities in a variety of operational phases (e.g., under construction, start-up, operating, shutdown, closed-down, and decommissioned). Safeguards optimization for each different facility type and operational phase is essential for the effectiveness of safeguards implementation. The IAEA’s current guidance regarding safeguards for the different facility types in the various lifecycle phases is provided in its Design Information Examination (DIE) and Verification (DIV) procedure. 1 Greater efficiency in safeguarding facilities that are shut down or closed down, including those being decommissioned, could allow the IAEA to use a greater portion of its effort to conduct other verification activities. Consequently, the National Nuclear Security Administration’s Office of International Nuclear Safeguards sponsored this study to evaluate whether there is an opportunity to optimize safeguards approaches for facilities that are shutdown or closed-down. The purpose of this paper is to examine existing safeguards approaches for shutdown and closed-down facilities, including facilities being decommissioned, and to seek to identify whether they may be optimized.

Neutron physical investigations on the shutdown effect of small boronated absorbing spheres for pebble-bed high-temperature gas-cooled reactors

International Nuclear Information System (INIS)

Sgouridis, S.; Schurrer, F.; Muller, H.; Ninaus, W.; Oswald, K.; Neef, R.D.; Schaal, H.

1987-01-01

An emergency shutdown system for high-temperature gas-cooled pebble-bed reactors is proposed in addition to the common absorber rod shutdown system. This system is based on the strongly absorbing effect of small boronated graphite spheres (called KLAK), which trickle in case of emergency by gravity from the top reflector into the reactor core. The inner reflector of the Siemens-Argonaut reactor was substituted by an assembly of spherical Arbeitsgemeinschaft Versuchsreaktor fuel elements, and the shutdown effect was examined by installing well-defined KLAK nests inside this assembly. The purpose was to develop and prove a calculational procedure for determining criticality values for assemblies of large fuel spheres and small absorbing spheres

Quality assurance program plan fuel supply shutdown project

International Nuclear Information System (INIS)

Metcalf, I.L.

1998-01-01

This Quality Assurance Program plan (QAPP) describes how the Fuel Supply Shutdown (FSS) project organization implements the quality assurance requirements of HNF-MP-599, Project Hanford Quality Assurance Program Description (QAPD) and the B and W Hanford Company Quality Assurance Program Plan (QAPP), FSP-MP-004. The QAPP applies to facility structures, systems, and components and to activities (e.g., design, procurement, testing, operations, maintenance, etc.) that could affect structures, systems, and components. This QAPP also provides a roadmap of applicable Project Hanford Policies and Procedures (PHPP) which may be utilized by the FSS project organization to implement the requirements of this QAPP

Preliminary estimates of dose and residual activation of selected components in ring collimation straight of the SNS

International Nuclear Information System (INIS)

Ludewig, H.; Catalan-Lasheras, N.; Simos, N.; Walker, J.; Mallen, A.; Wei, J.; Todosow, M.

2000-01-01

The highest doses to components in the SNS ring are expected to be to those located in the collimation straight section. In this paper the authors present estimated doses to magnets and cable located between collimators. In addition the buildup of relatively long half-life radioactive isotopes is estimated, following machine operation and shutdown. Finally, the potential dose to operators approaching the machine following operation and shutdown for four hours is made. The results indicate that selected components might require replacement after several years of full power operation. In addition, the reflection of gamma-rays from the tunnel walls contribute a non-negligible amount to the dose of an operator in the tunnel following machine shutdown

Examination of risk significant configuration during low power and shutdown with ORION and PSA

Energy Technology Data Exchange (ETDEWEB)

Park, Chul Kyu; Oh, Seung Jong [KEPCO International Nuclear Graduate School, Ulsan (Korea, Republic of)

2015-10-15

This paper suggests an approach to calculate the increased CDF corresponding to Orange and Red states in ORION program and analyzed the result of calculation. This approach is expected to be useful for checking the adequacy of the LPSD PSA. And also, the result of this calculation can provide the information about which SSCs for certain SF are more sensitive to risk in particular POS. Defense-in-depth is a safety philosophy in which multiple lines of defense and conservative design and evaluation methods are applied to ensure the safety of the public. Based on this philosophy EPRI developed Outage Risk Assessment and Management (ORAM) program as a qualitative assessment to better manage the risk during low power and shutdown event after the Vogtle loss of vital AC power and RHR event in 1990. Each risk level of RED, ORANGE color status caused by the degradation of each key safety function might be different depend on the importance of each key safety function. However we can't know how much different. If we know the quantitative information about the risk level represented by color, we can take and prepare concrete actions to reduce the risk level of the plant with rescheduling maintenance, strengthen surveillance for important safety function, and developing outage management strategy. The probabilistic safety analysis for low power and shutdown period can provide risk information with quantitative value related on the degradation of redundancy and diversity level for the safety functions during outage. In this study, we calculated the increased Core Damage frequency (CDF) of each RED and ORANGE states in ORION program caused by the degradation of each key safety function by modifying LPSD PSA model. The result of calculation and analysis could be effective to check adequacy and find improvement for these two methods.

Corrosion product behaviour in the Loviisa nuclear power plant primary coolant: measures taken to lower radiation levels by modified shutdown procedures

International Nuclear Information System (INIS)

Jaernstroem, R.T.

1983-01-01

The primary circuit chemistry of the Loviisa nuclear power plant differs in some respects from the concepts commonly used in PWRs. In general, Loviisa 1, which is now in its sixth cycle, and Loviisa 2, which is in its second refuelling and maintenance shutdown (October 1982), are very clean compared with several other PWRs and it seems to be possible to keep the radiation levels low and even reduce them by using correct chemistry during operation; the shutdown conditions seem to have great influence on this matter. These modified shutdown conditions and their influence on radiation levels, dose rates and radwaste buildup are discussed. (author)

Type and timing of childhood maltreatment and severity of shutdown dissociation in patients with schizophrenia spectrum disorder.

Directory of Open Access Journals (Sweden)

Inga Schalinski

Full Text Available Dissociation, particularly the shutting down of sensory, motor and speech systems, has been proposed to emerge in susceptible individuals as a defensive response to traumatic stress. In contrast, other individuals show signs of hyperarousal to acute threat. A key question is whether exposure to particular types of stressful events during specific stages of development can program an individual to have a strong dissociative response to subsequent stressors. Vulnerability to ongoing shutdown dissociation was assessed in 75 inpatients (46 M/29 F, M = 31 ± 10 years old with schizophrenia spectrum disorder and related to number of traumatic events experienced or witnessed during childhood or adulthood. The Maltreatment and Abuse Chronology of Exposure (MACE scale was used to collect retrospective recall of exposure to ten types of maltreatment during each year of childhood. Severity of shutdown dissociation was related to number of childhood but not adult traumatic events. Random forest regression with conditional trees indicated that type and timing of childhood maltreatment could predictably account for 31% of the variance (p < 0.003 in shutdown dissociation, with peak vulnerability occurring at 13-14 years of age and with exposure to emotional neglect followed by various forms of emotional abuse. These findings suggest that there may be windows of vulnerability to the development of shutdown dissociation. Results support the hypothesis that experienced events are more important than witnessed events, but challenge the hypothesis that "life-threatening" events are a critical determinant.

Effect of the Online Game Shutdown Policy on Internet Use, Internet Addiction, and Sleeping Hours in Korean Adolescents.

Science.gov (United States)

Choi, Jiyun; Cho, Hyunseok; Lee, Seungmin; Kim, Juyeong; Park, Eun-Cheol

2018-05-01

Internet addiction has emerged as a major public health problem worldwide. In November 2011, the South Korean government implemented an online game shutdown policy, lasting from 12:00 to 6:00 am, as a means of preventing Internet addiction in adolescents aged 15 or below. This study analyzed the effect of this shutdown policy on adolescent Internet use, addiction, and sleeping hours. We analyzed data collected from the Korea Youth Risk Behavior Web-based Survey from 2011 to 2015. Respondents were divided into two groups by age: aged 15 or below (male = 76,048, female = 66,281) and aged 16 or above (male = 52,568, female = 49,060). A difference-in-difference analysis was used to evaluate the effect of this shutdown policy. In 2012, which is immediately following policy enforcement, daily amount of Internet use (in minutes) decreased more in adolescents affected by the policy (i.e., the aged 15 or below group). However, it steadily increased in 2013, 2014, 2015, and showed no meaningful long-term improvements 4 years after policy implementation (-3.648 minutes in 2012 [p = .001], -3.204 minutes in 2013 [p = .011], -1.140 minutes in 2014 [p = .384], and 2.190 minutes in 2015 [p = .107]). The shutdown policy did not alter Internet addiction or sleeping hours. Interestingly, female adolescents, adolescents with low academic performance, and adolescents with low exercise levels exhibited comparatively stronger and longer lasting initial declines in Internet usage. The shutdown policy had practically insignificant effects in reducing Internet use for target adolescents. Thus, policymakers aiming to reduce or prevent Internet addiction should use different strategies. Copyright © 2017 The Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.

Transient fission product release during reactor shutdown and startup

International Nuclear Information System (INIS)

Hunt, C.E.L.; Lewis, B.J.

1995-01-01

Sweep gas experiments performed at CRL from 1979 to 1985 have been analysed to determine the fraction of the fission product gas inventory that is released on reactor shutdown and startup. Empirical equations were derived and applied to calculate the xenon release from companion fuel elements and from a well documented experimental fuel bundle irradiated in the NRU reactor. The measured gas release could be matched to within about a factor of two for an experimental irradiation with a burnup of 217 MWh/kgU. (author)

Duality-based algorithms for scheduling on unrelated parallel machines

NARCIS (Netherlands)

van de Velde, S.L.; van de Velde, S.L.

1993-01-01

We consider the following parallel machine scheduling problem. Each of n independent jobs has to be scheduled on one of m unrelated parallel machines. The processing of job J[sub l] on machine Mi requires an uninterrupted period of positive length p[sub lj]. The objective is to find an assignment of

Machine safety: proper safeguarding techniques.

Science.gov (United States)

Martin, K J

1992-06-01

1. OSHA mandates certain safeguarding of machinery to prevent accidents and protect machine operators. OSHA specifies moving parts that must be guarded and sets criteria for the guards. 2. A 1989 OSHA standard for lockout/tagout requires locking the energy source during maintenance, periodically inspecting for power transmission, and training maintenance workers. 3. In an amputation emergency, first aid for cardiopulmonary resuscitation, shock, and bleeding are the first considerations. The amputated part should be wrapped in moist gauze, placed in a sealed plastic bag, and placed in a container of 50% water and 50% ice for transport. 4. The role of the occupational health nurse in machine safety is to conduct worksite analyses to identify proper safeguarding and to communicate deficiencies to appropriate personnel; to train workers in safe work practices and observe compliance in the use of machine guards; to provide care to workers injured by machines; and to reinforce safe work practices among machine operators.

Uncertainty reduction requirements in cores designed for passive reactivity shutdown

International Nuclear Information System (INIS)

Wade, D.C.

1988-01-01

The first purpose of this paper is to describe the changed focus of neutronics accuracy requirements existing in the current US advanced LMR development program where passive shutdown is a major design goal. The second purpose is to provide the background and rationale which supports the selection of a formal data fitting methodology as the means for the application of critical experiment measurements to meet these accuracy needs. 6 refs., 1 fig., 2 tabs

Magnetic latch trigger for inherent shutdown assembly

International Nuclear Information System (INIS)

Sowa, E.S.

1976-01-01

An inherent shutdown assembly for a nuclear reactor is provided. A neutron absorber is held ready to be inserted into the reactor core by a magnetic latch. The latch includes a magnet whose lines of force are linked by a yoke of material whose Curie point is at the critical temperature of the reactor at which the neutron absorber is to be inserted into the reactor core. The yoke is in contact with the core coolant or fissionable material so that when the coolant or the fissionable material increase in temperature above the Curie point the yoke loses its magnetic susceptibility and the magnetic link is broken, thereby causing the absorber to be released into the reactor core. 6 claims, 3 figures

Reactor shutdown back-up system

International Nuclear Information System (INIS)

Hirao, Seizo; Sakashita, Motoaki.

1982-01-01

Purpose: To prevent back flow of poison upon injection to a moderator recycling pipeway. Constitution: In a nuclear reactor comprising a moderator recycling system for recycling and cooling moderator through a control rod guide pipe and a rapid poison injection system for rapidly injecting a poison solution at high density into the moderator by way of the same control rod guide pipe as a reactor shutdown back-up system, a mechanism is provided for preventing the back flow of a poison solution at high density into the moderator recycling system upon rapid injection of poison. An orifice provided in the joining pipeway to the control rod guide pipe on the side of the moderator recycling system is utilized as the back flow preventing device for the poison solution and the diameter for the orifice is determined so as to provide a constant ratio between the pressure loss in the control rod guide pipe and the pressure loss in the moderator recycling system pipe line upon usual reactor operation. (Kawakami, Y.)

Decontamination and decommissioning the Tokamak Fusion Test Reactor

International Nuclear Information System (INIS)

Walton, G.R.; Perry, E.D.; Commander, J.C.; Spampinato, P.T.

1994-01-01

The Tokamak Fusion Test Reactor (TFTR) is scheduled to complete its end-of-life deuterium-tritium (D-T) experiments in September 1994. The D-T operation will result in the TFTR machine structure becoming activated, and plasma facing and vacuum components will be contaminated with tritium. The resulting machine activation levels after a two year cooldown period will allow hands on dismantling for external structures, but require remote dismantling for the vacuum vessel. The primary objective of the Decontamination and Decommissioning (D ampersand D) Project is to provide a facility for construction of a new Department of Energy (DOE) experimental fusion reactor by March 1998. The project schedule calls for a two year shutdown period when tritium decontamination of the vacuum vessel, neutral beam injectors and other components will occur. Shutdown will be followed by an 18 month period of D ampersand D operations. The technical objectives of the project are to: safely dismantle and remove components from the test cell complex; package disassembled components in accordance with applicable regulations; ship packages to a DOE approved disposal or material recycling site; and develop expertise using remote disassembly techniques on a large scale fusion facility. This paper discusses the D ampersand D objectives, the facility to be decommissioned, and the technical plan that will be implemented

Shutdown channels and fitted interlocks in atomic reactors

International Nuclear Information System (INIS)

Furet, J.; Landauer, C.

1968-01-01

This catalogue consists of tables (one per reactor) giving the following information: number and type of detectors, range of the shutdown channels, nature of the associated electronics, thresholds setting off the alarms, fitted interlocks. These cards have been drawn up with a view to an examination of the reactors safety by the 'Reactor Safety Sub-Commission', they take into account the latest decisions. The reactors involved in this review are: Azur, Cabri, Castor-Pollux, Cesar-Marius-2, Edf-2, EL3, EL4, Eole, G1, G2-G3, Harmonie, Isis, Masurca, Melusine, Minerve, Osiris, Pegase, Peggy, PAT, Rapsodie, SENA, Siloe, Siloette, Triton-Nereide, and Ulysse. (authors) [fr

Machine utilisation and operation experience with Jet from 1983

International Nuclear Information System (INIS)

Green, B.J.; Chuilon, P.; Noble, B.; Saunders, R.; Webberley, D.

1989-01-01

The operation of JET commenced in June 1983 and is scheduled until the end of 1992. This seemingly long period is actually quite limited when compared with the time needed to implement and commission the planned machine enhancements, and pursue research and developments which result from the experiments. There is an ever-present urgency to make the best use of the machine. 1983-84 was a learning period and only in 1985 was it felt worthwhile to adopt double-shift day working. Data has been compiled and analysed for utilisation of the machine, delays in terms of time lost and systems involved, and number and frequency of machine pulses. This paper presents an overall picture of machine availability and utilisation. It describes the JET operational arrangements and the experience of system faults. Finally, it draws conclusions and identifies lessons learned which may be relevant to the next stage of fusion power development

Machine utilisation and operation experience with JET from 1983

International Nuclear Information System (INIS)

Green, B.J.; Chuilon, P.; Noble, B.; Saunders, R.; Webberley, D.

1989-01-01

The operation of JET commenced in June 1983 and is scheduled until the end of 1992. This seemingly long period is actually quite limited when compared with the time needed to implement and commission the planned machine enhancements, and pursue research and developments which result from the experiments. There is an ever-present urgency to make the use of the machine. 1983-84 was a learning period and only in 1985 was it felt worthwhile to adopt double-shift day working. Data has been compiled and analysed for utilisation of the machine, delays in terms of time lost and system involved, and number and frequency of machine pulses. This paper presents an overall picture of machine availability and utilisation. It describes the JET operational arrangements and the experience of system faults. Finally, it draws conclusions and identifies lessons learned which may be relevant to the next stage of fusion power development. (author). 9 figs

Wireless Monitoring of Induction Machine Rotor Physical Variables

Directory of Open Access Journals (Sweden)

Jefferson Doolan Fernandes

2017-11-01

Full Text Available With the widespread use of electric machines, there is a growing need to extract information from the machines to improve their control systems and maintenance management. The present work shows the development of an embedded system to perform the monitoring of the rotor physical variables of a squirrel cage induction motor. The system is comprised of: a circuit to acquire desirable rotor variable(s and value(s that send it to the computer; a rectifier and power storage circuit that converts an alternating current in a continuous current but also stores energy for a certain amount of time to wait for the motor’s shutdown; and a magnetic generator that harvests energy from the rotating field to power the circuits mentioned above. The embedded system is set on the rotor of a 5 HP squirrel cage induction motor, making it difficult to power the system because it is rotating. This problem can be solved with the construction of a magnetic generator device to avoid the need of using batteries or collector rings and will send data to the computer using a wireless NRF24L01 module. For the proposed system, initial validation tests were made using a temperature sensor (DS18b20, as this variable is known as the most important when identifying the need for maintenance and control systems. Few tests have shown promising results that, with further improvements, can prove the feasibility of using sensors in the rotor.

Wireless Monitoring of Induction Machine Rotor Physical Variables.

Science.gov (United States)

Doolan Fernandes, Jefferson; Carvalho Souza, Francisco Elvis; Cipriano Maniçoba, Glauco George; Salazar, Andrés Ortiz; de Paiva, José Alvaro

2017-11-18

With the widespread use of electric machines, there is a growing need to extract information from the machines to improve their control systems and maintenance management. The present work shows the development of an embedded system to perform the monitoring of the rotor physical variables of a squirrel cage induction motor. The system is comprised of: a circuit to acquire desirable rotor variable(s) and value(s) that send it to the computer; a rectifier and power storage circuit that converts an alternating current in a continuous current but also stores energy for a certain amount of time to wait for the motor's shutdown; and a magnetic generator that harvests energy from the rotating field to power the circuits mentioned above. The embedded system is set on the rotor of a 5 HP squirrel cage induction motor, making it difficult to power the system because it is rotating. This problem can be solved with the construction of a magnetic generator device to avoid the need of using batteries or collector rings and will send data to the computer using a wireless NRF24L01 module. For the proposed system, initial validation tests were made using a temperature sensor (DS18b20), as this variable is known as the most important when identifying the need for maintenance and control systems. Few tests have shown promising results that, with further improvements, can prove the feasibility of using sensors in the rotor.

Optimizing virtual machine placement for energy and SLA in clouds using utility functions

Directory of Open Access Journals (Sweden)

Abdelkhalik Mosa

2016-10-01

Full Text Available Abstract Cloud computing provides on-demand access to a shared pool of computing resources, which enables organizations to outsource their IT infrastructure. Cloud providers are building data centers to handle the continuous increase in cloud users’ demands. Consequently, these cloud data centers consume, and have the potential to waste, substantial amounts of energy. This energy consumption increases the operational cost and the CO2 emissions. The goal of this paper is to develop an optimized energy and SLA-aware virtual machine (VM placement strategy that dynamically assigns VMs to Physical Machines (PMs in cloud data centers. This placement strategy co-optimizes energy consumption and service level agreement (SLA violations. The proposed solution adopts utility functions to formulate the VM placement problem. A genetic algorithm searches the possible VMs-to-PMs assignments with a view to finding an assignment that maximizes utility. Simulation results using CloudSim show that the proposed utility-based approach reduced the average energy consumption by approximately 6 % and the overall SLA violations by more than 38 %, using fewer VM migrations and PM shutdowns, compared to a well-known heuristics-based approach.

Preliminary aseismic analysis on bolts of driving mechanism in absorption sphere shutdown system

International Nuclear Information System (INIS)

Chen Feng; Li Tianjin; Zhang Zhengming; Huang Zhiyong; Bo Hanliang

2012-01-01

The absorption sphere shutdown system performs an important role in reactivity regulating and control. Driving mechanism is a set of key mechanical moving parts which is used to control falling of absorption spheres in absorption sphere shutdown system. It is about 5 m for driving mechanism with the slim structure, which is connected with the upper supported plate of metal reactor internals through storage vessel with bolts. Both the storage vessel and driving mechanism are equipment of seismic classification I. It is significant to calculate and check the bolts strength of driving mechanism. In this paper, complicate structure of driving mechanism was simplified to three variable cross sections and statically indeterminate problem was solved. The bolts at the bottom and on the top of the storage vessel were calculated and checked. The preliminary results indicate that the bolts strength is reliable and safe, and the supporting force at the most weak point of driving mechanism is as well obtained. (authors)

Dynamic Response of AP1000 Nuclear Island Due to Safe Shutdown Earthquake Loading

Directory of Open Access Journals (Sweden)

Gan Buntara S.

2017-01-01

Full Text Available AP1000 is a standard nuclear power plant developed by Westinghouse and its partners by using an advanced passive safety feature. Among the five principle building structures, namely the nuclear island, turbine building, annex building, diesel generator building and radwaste building, the safety of the nuclear island building is the most concerned. This paper investigates the dynamic response of the nuclear island building of the AP1000 plant subjected to safe shutdown earthquake loadings. A finite element model for the building, which is assumed to be built in a hard-rock base, is developed and its dynamic response is computed with the aid of the commercial finite element package ANSYS. The dynamic characteristics, including the natural frequencies, the vibration modes, and the time histories for displacements, velocities, and accelerations of the building are obtained for two typical safe shutdown earthquakes, El Centro and Kobe earthquakes. The dynamic behavior of the building due to the earthquakes and its safety is examined and highlighted.

The Intelligent Safety System: could it introduce complex computing into CANDU shutdown systems

International Nuclear Information System (INIS)

Hall, J.A.; Hinds, H.W.; Pensom, C.F.; Barker, C.J.; Jobse, A.H.

1984-07-01

The Intelligent Safety System is a computerized shutdown system being developed at the Chalk River Nuclear Laboratories (CRNL) for future CANDU nuclear reactors. It differs from current CANDU shutdown systems in both the algorithm used and the size and complexity of computers required to implement the concept. This paper provides an overview of the project, with emphasis on the computing aspects. Early in the project several needs leading to an introduction of computing complexity were identified, and a computing system that met these needs was conceived. The current work at CRNL centers on building a laboratory demonstration of the Intelligent Safety System, and evaluating the reliability and testability of the concept. Some fundamental problems must still be addressed for the Intelligent Safety System to be acceptable to a CANDU owner and to the regulatory authorities. These are also discussed along with a description of how the Intelligent Safety System might solve these problems

Global shutdown dose rate maps for a DEMO conceptual design

International Nuclear Information System (INIS)

Leichtle, D.; Pereslavtsev, P.; Sanz, J.; Catalan, J.P.; Juarez, R.

2015-01-01

Highlights: • Application of R2S-method on high-resolution full torus sector mesh for DEMO. • Absorbed dose rates after shutdown for a variely of RH equipment at typical locations. • Idenification of radiation levels at several port based locations. - Abstract: For the calculations of highly reliable shutdown dose rate (SDR) maps in fusion devices like a DEMO plant, the Rigorous-2-step (R2S) method is nowadays routinely applied using high-resolution decay gamma sources from initial high-resolution neutron flux meshes activating all materials in the system. This approach has been utilized in the present paper with the objective to provide SDR results relevant for RH systems of a conceptual DEMO design developed in the EU. The primary objective was to assess specific locations of interest for RH equipment inside the vessel and along the extension of maintenance ports. To this end, a provisional DEMO MCNP model has been used, featuring HCLL-type blankets, tungsten/copper divertor, manifolds, vacuum vessel with ports and toroidal field coils. The operational scenario assumed 2.1 GW fusion power and a life-time of 20 years with plant availability of 30%, where removable parts will be extracted after 5.2 years. Results of absorbed dose rate distributions for several relevant materials are presented and discussed in terms of the different contributions from the various activated components.

Global shutdown dose rate maps for a DEMO conceptual design

Energy Technology Data Exchange (ETDEWEB)

Leichtle, D., E-mail: dieter.leichtle@f4e.europa.eu [Karlsruhe Institute of Technology KIT, Institute for Neutron Physics and Reactor Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Pereslavtsev, P. [Karlsruhe Institute of Technology KIT, Institute for Neutron Physics and Reactor Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Sanz, J.; Catalan, J.P.; Juarez, R. [Universidad Nacional de Educación a Distancia(UNED), E.T.S. Ingenieros Industriales, C/ Juan del Rosal 12, 28040 Madrid (Spain)

2015-10-15

Highlights: • Application of R2S-method on high-resolution full torus sector mesh for DEMO. • Absorbed dose rates after shutdown for a variely of RH equipment at typical locations. • Idenification of radiation levels at several port based locations. - Abstract: For the calculations of highly reliable shutdown dose rate (SDR) maps in fusion devices like a DEMO plant, the Rigorous-2-step (R2S) method is nowadays routinely applied using high-resolution decay gamma sources from initial high-resolution neutron flux meshes activating all materials in the system. This approach has been utilized in the present paper with the objective to provide SDR results relevant for RH systems of a conceptual DEMO design developed in the EU. The primary objective was to assess specific locations of interest for RH equipment inside the vessel and along the extension of maintenance ports. To this end, a provisional DEMO MCNP model has been used, featuring HCLL-type blankets, tungsten/copper divertor, manifolds, vacuum vessel with ports and toroidal field coils. The operational scenario assumed 2.1 GW fusion power and a life-time of 20 years with plant availability of 30%, where removable parts will be extracted after 5.2 years. Results of absorbed dose rate distributions for several relevant materials are presented and discussed in terms of the different contributions from the various activated components.

Daily sea level prediction at Chiayi coast, Taiwan using extreme learning machine and relevance vector machine

Science.gov (United States)

Imani, Moslem; Kao, Huan-Chin; Lan, Wen-Hau; Kuo, Chung-Yen

2018-02-01

The analysis and the prediction of sea level fluctuations are core requirements of marine meteorology and operational oceanography. Estimates of sea level with hours-to-days warning times are especially important for low-lying regions and coastal zone management. The primary purpose of this study is to examine the applicability and capability of extreme learning machine (ELM) and relevance vector machine (RVM) models for predicting sea level variations and compare their performances with powerful machine learning methods, namely, support vector machine (SVM) and radial basis function (RBF) models. The input dataset from the period of January 2004 to May 2011 used in the study was obtained from the Dongshi tide gauge station in Chiayi, Taiwan. Results showed that the ELM and RVM models outperformed the other methods. The performance of the RVM approach was superior in predicting the daily sea level time series given the minimum root mean square error of 34.73 mm and the maximum determination coefficient of 0.93 (R2) during the testing periods. Furthermore, the obtained results were in close agreement with the original tide-gauge data, which indicates that RVM approach is a promising alternative method for time series prediction and could be successfully used for daily sea level forecasts.

Containment closure time following loss of cooling under shutdown conditions of YGN units 3 and 4

International Nuclear Information System (INIS)

Seul, Kwang Won; Bang, Young Seok; Kim, Se Won; Kim, Hho Jung

1998-01-01

The YGN Units 3 and 4 plant conditions during shutdown operation were reviewed to identify the possible event scenarios following the loss of shutdown cooling. The thermal hydraulic analyses were performed for the five cases of RCS configurations under the worst event scenario, unavailable secondary cooling and no RCS inventory makeup, using the RELAP5/MOD3.2 code to investigate the plant behavior. From the analyses results, times to boil, times to core uncovery and times to core heat up were estimated to determine the containment closure time to prevent the uncontrolled release of fission products to atmosphere. These data provide useful information to the abnormal procedure to cope with the event

Shutdown dose rate analysis of European test blanket modules shields in ITER Equatorial Port #16

Energy Technology Data Exchange (ETDEWEB)

Juárez, Rafael, E-mail: rjuarez@ind.uned.es [Departamento de Ingeniería Energética, ETSII-UNED, Calle Juan del Rosal 12, Madrid 28040 (Spain); Sauvan, Patrick; Perez, Lucia [Departamento de Ingeniería Energética, ETSII-UNED, Calle Juan del Rosal 12, Madrid 28040 (Spain); Panayotov, Dobromir; Vallory, Joelle; Zmitko, Milan; Poitevin, Yves [Fusion for Energy (F4E), Torres Diagonal Litoral B3, Josep Pla 2, Barcelona 08019 (Spain); Sanz, Javier [Departamento de Ingeniería Energética, ETSII-UNED, Calle Juan del Rosal 12, Madrid 28040 (Spain)

2016-11-01

Highlights: • Nuclear analysis for European TBMs and shields, in ITER Equatorial Port #16, has been conducted in support of the ‘Concept Design Review’ from ITER. • The objective of the work is the characterization of the Shutdown Dose Rates at Equatorial Port #16 interspace. • The role played by the TBM and TBM shields, the equatorial port gaps and the vacuum vessel permeation, in terms of neutron flux transmission is assessed. • The role played by the TBM, TBM shields, Port Plug Frame, Pipe Forest and the machine in terms of activation is also investigated. - Abstract: ‘Fusion for Energy’ (F4E) is designing, developing, and implementing the European Helium-Cooled Lead-Lithium (HCLL) and Helium-Cooled Pebble-Bed (HCPB) Test Blanket Systems (TBSs) for ITER (Nuclear Facility INB-174). An essential element of the Conceptual Design Review (CDR) of these TBSs is the demonstration of capability of Test Blanket Modules (TBM) and their shields to fulfil their function and comply with the design requirements. One of the TBM shields highly relevant design aspects is the project target for shutdown dose rates (SDDR) in the interspace. We investigated two functions of the TBMs and TBM shields—the neutron flux attenuation along the shields, and the reduction of the activation of the components contributing to SDDR. It is shown that TBMs and TBM shields reduce significantly the neutron flux in the port plug (PP). In terms of neutron flux attenuation, the TBM shield provides sufficient neutron flux reduction, being responsible for 5 × 10{sup 6} n/cm{sup 2} s at port interspace, while the EPP gaps and BSM gaps are responsible for 5 × 10{sup 7} n/cm{sup 2} s each. When considering closed upper, lower and lateral neighbour equatorial ports (thus, excluding the cross-talk between ports), a SDDR of 121 μSv/h averaged near the port closure flange was obtained, out of which, only 4 μSv/h are due to the activation of TBMs and TBM shields. Maximum SDDR in the range

On the speed of response of an FPGA-based shutdown system in CANDU nuclear power plants

Energy Technology Data Exchange (ETDEWEB)

She Jingke, E-mail: jshe2@uwo.ca [Department of Electrical and Computer Engineering, The University of Western Ontario, London, Ontario, N6A 5B9 (Canada); Jiang Jin, E-mail: jjiang@eng.uwo.ca [Department of Electrical and Computer Engineering, The University of Western Ontario, London, Ontario, N6A 5B9 (Canada)

2011-06-15

Highlights: > Design and implementation of an FPGA-based CANDU SDS1. > Hardware-in-the-loop simulation for performance evaluation involved with an NPP simulator. > Comparison of the response time between FPGA-based trip channel and software-based PLC. - Abstract: Several issues in an FPGA based implementation of shutdown systems in CANDU nuclear power plants have been investigated in this paper. A particular attention is on the response time of an FPGA implementation of safety shutdown systems in comparison with operating system based software solutions as in existing CANDU plants. The trip decision logic under 'steam generator (SG) level low' condition has been examined in detail. The design and implementation of this logic on an FPGA platform have been carried out. The functionality tests are performed in a hardware-in-the-loop (HIL) environment by connecting the FPGA based system to an NPP simulator, and replacing one channel of Shutdown System Number 1 (SDS1) in the simulator by the FPGA implementation. The response time of the designed system is also measured through multiple tests under different conditions, and statistical data analysis has been performed. The results of the response time tests are compared against those of a software-based implementation of the same trip logic.

Gram staining with an automatic machine.

Science.gov (United States)

Felek, S; Arslan, A

1999-01-01

This study was undertaken to develop a new Gram-staining machine controlled by a micro-controller and to investigate the quality of slides that were stained in the machine. The machine was designed and produced by the authors. It uses standard 220 V AC. Staining, washing, and drying periods are controlled by a timer built in the micro-controller. A software was made that contains a certain algorithm and time intervals for the staining mode. One-hundred and forty smears were prepared from Escherichia coli, Staphylococcus aureus, Neisseria sp., blood culture, trypticase soy broth, direct pus and sputum smears for comparison studies. Half of the slides in each group were stained with the machine, the other half by hand and then examined by four different microbiologists. Machine-stained slides had a higher clarity and less debris than the hand-stained slides (p stained slides, some Gram-positive organisms showed poor Gram-positive staining features (p Gram staining with the automatic machine increases the staining quality and helps to decrease the work load in a busy diagnostic laboratory.

CORAL and COOL during the LHC long shutdown.

CERN Document Server

Valassi, Andrea; Dulstra, D; Goyal, N; Salnikov, A; Trentadue, R; Wache, M

2014-01-01

CORAL and COOL are two software packages used by the LHC experiments for managing detector conditions and other types of data using relational database technologies. They have been developed and maintained within the LCG Persistency Framework, a common project of the CERN IT department with ATLAS, CMS and LHCb. This presentation reports on the status of CORAL and COOL at the time of CHEP2013, covering the new features and enhancements in both packages, as well as the changes and improvements in the software process infrastructure. It also reviews the usage of the software in the experiments and the outlook for ongoing and future activities during the LHC long shutdown (LS1) and beyond.

CORAL and COOL during the LHC long shutdown

CERN Multimedia

Valassi, A; Dykstra, D; Goyal, N; Salnikov, A; Trentadue, R; Wache, M

2013-01-01

CORAL and COOL are two software packages used by the LHC experiments for managing detector conditions and other types of data using relational database technologies. They have been developed and maintained within the LCG Persistency Framework, a common project of the CERN IT department with ATLAS, CMS and LHCb. This presentation reports on the status of CORAL and COOL at the time of CHEP2013, covering the new features and enhancements in both packages, as well as the changes and improvements in the software process infrastructure. It also reviews the usage of the software in the experiments and the outlook for ongoing and future activities during the LHC long shutdown (LS1) and beyond.

Loss of benefits resulting from mandated nuclear plant shutdowns

International Nuclear Information System (INIS)

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

1982-01-01

This paper identifies and discusses some of the important consequences of nuclear power plant unavailability, and quantifies a number of technical measures of loss of benefits that result from regulatory actions such as licensing delays and mandated nuclear plant outages. The loss of benefits that accompany such regulatory actions include increased costs of systems generation, increased demand for nonnuclear and often scarce fuels, and reduced system reliability. This paper is based on a series of case studies, supplemented by sensitivity studies, on hypothetical nuclear plant shutdowns. These studies were developed by Argonne in cooperation with four electric utilities

Evaluation of slow shutdown system flux detectors in Point Lepreau Generating Station - II: dynamic compensation error analysis

Energy Technology Data Exchange (ETDEWEB)

Anghel, V.N.P.; Sur, B. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada); Taylor, D. [New Brunswick Power Nuclear, Point Lepreau, New Brunswick (Canada)

2009-07-01

CANDU reactors are protected against reactor overpower by two independent shutdown systems: Shut Down System 1 and 2 (SDS1 and SDS2). At the Point Lepreau Generating Station (PLGS), the shutdown systems can be actuated by measurements of the neutron flux from Platinum-clad Inconel In-Core Flux Detectors. These detectors have a complex dynamic behaviour, characterized by 'prompt' and 'delayed' components with respect to immediate changes in the in-core neutron flux. It was shown previously (I: Dynamic Response Characterization by Anghel et al., this conference) that the dynamic responses of the detectors changed with irradiation, with the SDS2 detectors having 'prompt' signal components that decreased significantly. In this paper we assess the implication of these changes for detector dynamic compensation errors by comparing the compensated detector response with the power-to-fuel and the power-to-coolant responses to neutron flux ramps as assumed by previous error analyses. The dynamic compensation error is estimated at any given trip time for all possible accident flux ramps. Some implications for the shutdown system trip set points, obtained from preliminary results, are discussed. (author)

Methods for nondestructive assay holdup measurements in shutdown uranium enrichment facilities

International Nuclear Information System (INIS)

Hagenauer, R.C.; Mayer, R.L. II.

1991-09-01

Measurement surveys of uranium holdup using nondestructive assay (NDA) techniques are being conducted for shutdown gaseous diffusion facilities at the Oak Ridge K-25 Site (formerly the Oak Ridge Gaseous Diffusion Plant). When in operation, these facilities processed UF 6 with enrichments ranging from 0.2 to 93 wt % 235 U. Following final shutdown of all process facilities, NDA surveys were initiated to provide process holdup data for the planning and implementation of decontamination and decommissioning activities. A three-step process is used to locate and quantify deposits: (1) high-resolution gamma-ray measurements are performed to generally define the relative abundances of radioisotopes present, (2) sizable deposits are identified using gamma-ray scanning methods, and (3) the deposits are quantified using neutron measurement methods. Following initial quantitative measurements, deposit sizes are calculated; high-resolution gamma-ray measurements are then performed on the items containing large deposits. The quantitative estimates for the large deposits are refined on the basis of these measurements. Facility management is using the results of the survey to support a variety of activities including isolation and removal of large deposits; performing health, safety, and environmental analyses; and improving facility nuclear material control and accountability records. 3 refs., 1 tab

Human-machine interface upgrade

International Nuclear Information System (INIS)

Kropik, M.; Matejka, K.; Sklenka, L.; Chab, V.

2002-01-01

The article describes a new human-machine interface that was installed at the VR-1 training reactor. The human-machine interface upgrade was completed in the summer 2001. The interface was designed with respect to functional, ergonomic and aesthetic requirements. The interface is based on a personal computer equipped with two displays. One display enables alphanumeric communication between the reactor operator and the nuclear reactor I and C. The second display is a graphical one. It presents the status of the reactor, principal parameters (as power, period), control rods positions, course of the reactor power. Furthermore, it is possible to set parameters, to show the active core configuration, to perform reactivity calculations, etc. The software for the new human-machine interface was produced with the InTouch developing tool of the Wonder-Ware Company. It is possible to switch the language of the interface between Czech and English because of many foreign students and visitors to the reactor. Microcomputer based communication units with proper software were developed to connect the new human-machine interface with the present reactor I and C. The new human-machine interface at the VR-1 training reactor improves the comfort and safety of the reactor utilisation, facilitates experiments and training, and provides better support for foreign visitors. (orig.)

Government Shutdown: Operations of Department of Defense During a Lapse in Appropriations

Science.gov (United States)

2011-04-01

proactive in working with creditors to reschedule debt repayments under these circumstances… c. Military personnel: During a shutdown of DoD activities due...creditors to reschedule debt repayments under these circumstances. The key point that both the creditor and the soldier should remember is that the...including Uniformed Services Treatment Facilities) including doctors, nurses , medical technicians, dentists, and essential support personnel (cooks

Brief account of the design philosophy for third Qinshan NPP shutdown safety system based on practical application

International Nuclear Information System (INIS)

Xiong Weihua

2005-01-01

Qinshan CANDU power plant is uses the Canadian proven CANDU6 nuclear power technology. It has two characteristic: 1. heavy water-as moderator and coolant; 2. natural uranium as the fuel and change fuel during normal operating. CANDU6 include four special safety system: the No.1 shutdown system (SDS No.1), the No.2 shutdown system (SDS No.2), the containment system, the emergency core cooling system (ECCS). QinShan CANDU power plant is the first commercial PHWR nuclear power plant in China. And some aspect is not similar to everybody. The intention of the article is to introduce the basic design and functions. (authors)

Concepts in developing technical means of accident shutdown of nuclear reactor

International Nuclear Information System (INIS)

Ionajtis, R.R.; Mikhajlov, M.P.; Cherkashov, Yu.M.

1992-01-01

Logic for realization of multistage (echelon) reactor accident shutdown system (ASS) is proposed on the basis of general safety concepts (OPB-88). ASS includes the basis stage with traditional composition of member systems (executive, control, providing ones), auxiliary (doubling) on the other principle of action and insuring (with direct action). Structural schemes of the system as a whole and member subsystems are presented. Recommendations on developing executive and control subsystems are given

A scoping evaluation of severe accidents at Surry and Grand Gulf Nuclear Power Plants resulting from earthquakes during shutdown conditions

International Nuclear Information System (INIS)

Budnitz, R.J.; Davis, P.R.

1991-01-01

This report explores the likelihood of seismic-initiated core damage accidents during refueling shutdown conditions at two nuclear power plants, Surry Unit I and Grand Gulf Unit 1. The effort is scoping in character, and has been performed primarily to establish if a potential problem exists sufficient to justify a more rigorous and more quantitative evaluation. A summary is presented of the important conclusions that have been reached. The most important conclusion is that the core-damage frequencies for earthquake-initiated accidents during shutdown at both Surry Unit I and Grand Gulf Unit I are found to be low in absolute terms. The reasons for this are that in their ability to respond to earthquakes during shutdowns, the plants both have large seismic capacities, well above their design-basis levels; and also that both sites enjoy among the lowest seismic hazards of any LWR sites in the US

Improving the action requirements of technical specifications: A risk-comparison of continued operation and plant shutdown

International Nuclear Information System (INIS)

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

1994-01-01

When the systems needed to remove decay heat are inoperable or degraded, the risk of shutting down the plant may be comparable to, or even higher than, that of continuing power operation with the equipment inoperable while giving priority to repairs. This concern arises because the plant may not have sufficient capability for removing decay heat during the shutdown. However, Technical Specifications (TSs) often require ''immediate'' shutdown of the plant. In this paper, the authors present risk-based analyses of the various operational policy alternatives available in such situations, with an example application to the standby service water (SSW) system of a BWR. These analyses can be used to define risk-effective requirements for those standby safety systems under discussion

Improving the action requirements of technical specifications: A risk-comparison of continued operation and plant shutdown

Energy Technology Data Exchange (ETDEWEB)

Kim, I.S.; Samanta, P.K. [Brookhaven National Lab., Upton, NY (United States); Mankamo, T.

1995-04-01

When the systems needed to remove decay heat are inoperable or degraded, the risk of shutting down the plant may be comparable to, or even higher than, that of continuing power operation with the equipment inoperable while giving priority to repairs. This concern arises because the plant may not have sufficient capability for removing decay heat during the shutdown. However, Technical Specifications (TSs) often require {open_quotes}immediate{close_quotes} shutdown of the plant. In this paper, we present risk-based analyses of the various operational policy alternatives available in such situations, with an example application to the standby service water (SSW) system of a BWR. These analyses can be used to define risk-effective requirements for those standby safety systems under discussion.

Containment closure time following loss of cooling under shutdown conditions of YGN units 3 and 4

Energy Technology Data Exchange (ETDEWEB)

Seul, Kwang Won; Bang, Young Seok; Kim, Se Won; Kim, Hho Jung [Korea Institute of Nuclear Safety, Taejon (Korea, Republic of)

1998-12-31

The YGN Units 3 and 4 plant conditions during shutdown operation were reviewed to identify the possible event scenarios following the loss of shutdown cooling. The thermal hydraulic analyses were performed for the five cases of RCS configurations under the worst event scenario, unavailable secondary cooling and no RCS inventory makeup, using the RELAP5/MOD3.2 code to investigate the plant behavior. From the analyses results, times to boil, times to core uncovery and times to core heat up were estimated to determine the containment closure time to prevent the uncontrolled release of fission products to atmosphere. These data provide useful information to the abnormal procedure to cope with the event. 6 refs., 7 figs., 2 tabs. (Author)

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

International Nuclear Information System (INIS)

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

2016-01-01

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

Management of accidental scenarios involving the loss of RHRS under shutdown conditions

International Nuclear Information System (INIS)

Serradell, V.; Villanueva, J.F.; Martorell, S.; Carlos, S.; Pelayo, F.; Mendizabal, R.; Sol, I.

2009-01-01

Results from current Probabilistic Safety Assessment studies of Nuclear Power Plants show the importance of some risky scenarios with the plant at low power and shutdown conditions as compared to the accident scenarios with the plant operating at full power. Technical Specifications establish the Limiting Conditions for operation to assure the plant integrity in each Plant Operational State (POS). Moreover, the plant configuration may differ from the beginning to the end of a certain Plant Operational State, so the Limiting Conditions for Operation (LCO) established could be revised as, depending on the plant configuration, the transient evolution may be slightly different. For a PWR plant, one of the most risky accidental sequences in shutdown is the loss of the residual heat removal system, Using the information provided by the plant low power probabilistic safety analysis (LPSA), which should address the Limiting Conditions for Operation imposed by the current Technical Specification, two situations are distinguished: Main Reactor Cooling System (RCS) fully filled with water and RCS partially filled. In addition, while the primary system is partially filled in Cold Shutdown, two different plant configurations can be distinguished, which depend on the particular POS: RCS open and closed. For each case, the corresponding Technical Specification establishes the path to evacuate the residual heat generated. This paper explores the possibility of having alternative or complementary sources for heat removal others than the ones established in the Technical Specification. Especial attention is paid to the role of Steam Generators as an effective heat sink and the possibility of restart of the redundant RHR train. Such alternatives will influence LPSA implementation results. To perform this analysis the loss of the RHR system in a PWR plant has been simulated using RELAP-5 considering the plant in different plant operational states. One of the main results of this work

Management of individual and collective dosimetry at Fessenheim nuclear plant. Evaluation after refueling shutdown

International Nuclear Information System (INIS)

Lamarre, D.; Waller, A.

1980-01-01

The principle of dosimetry management chosen by Fessenheim nuclear power station was originally consisted of two phases: - an automatic acquisition of individual doses realized by stylodosimeter readers; - a deferred data processing by computer. The whole system has not been used during the shutdown for the first refuelling of unit number one in view of encountered difficulties with perfecting of automatic readers prototype, this last phase has been replaced by a manual acquisition of doses. The dosimetry data processing has two main objects: - supervision of individual dosimetry for people who work in the nuclear power station; - knowledge of doses assigned for each working and equipment. Moreover, a first dosimetric result of the shutdown for refuelling of unit number one, enables to notice the workings which doses are the most important and written in percentage of total doses: regulatory controls: about 19%; - steam generators working: 16%; - working decontamination and making health physics screen (lock chamber) 10% [fr

Analysis of machining and machine tools

CERN Document Server

Liang, Steven Y

2016-01-01

This book delivers the fundamental science and mechanics of machining and machine tools by presenting systematic and quantitative knowledge in the form of process mechanics and physics. It gives readers a solid command of machining science and engineering, and familiarizes them with the geometry and functionality requirements of creating parts and components in today’s markets. The authors address traditional machining topics, such as: single and multiple point cutting processes grinding components accuracy and metrology shear stress in cutting cutting temperature and analysis chatter They also address non-traditional machining, such as: electrical discharge machining electrochemical machining laser and electron beam machining A chapter on biomedical machining is also included. This book is appropriate for advanced undergraduate and graduate mechani cal engineering students, manufacturing engineers, and researchers. Each chapter contains examples, exercises and their solutions, and homework problems that re...

Shutdown dose rates at ITER equatorial ports considering radiation cross-talk from torus cryopump lower port

Energy Technology Data Exchange (ETDEWEB)

Juárez, Rafael, E-mail: rjuarez@ind.uned.es [Departamento de Ingeniería Energética, ETSII-UNED, Calle Juan del Rosal 12, Madrid 28040 (Spain); Pampin, Raul [F4E, Torres Diagonal Litoral B3, Josep Pla 2, Barcelona 08019 (Spain); Levesy, Bruno [ITER Organization, 13115 Route de Vinon sur Verdon, St Paul Lez Durance (France); Moro, Fabio [ENEA, Via Enrico Fermi 45, Frascati, Rome (Italy); Suarez, Alejandro [ITER Organization, 13115 Route de Vinon sur Verdon, St Paul Lez Durance (France); Sanz, Javier [Departamento de Ingeniería Energética, ETSII-UNED, Calle Juan del Rosal 12, Madrid 28040 (Spain)

2015-11-15

Shutdown dose rates for planned maintenance purposes is an active research field in ITER. In this work the radiation (neutron and gamma) cross-talk between ports in the most conservative case foreseen in ITER is investigated: the presence of a torus cryopump lower port, mostly empty for pumping efficiency reasons. There will be six of those ports: #4, #6, #10, #12, #16 and #18. The equatorial ports placed above them will receive a significant amount of additional radiation affecting the shutdown dose rates during in situ maintenance activities inside the cryostat, and particularly in the port interspace area. In this study a general situation to all the equatorial ports placed above torus cryopump lower ports is considered: a generic diagnostics equatorial port placed above the torus cryopump lower port (LP#4). In terms of shutdown dose rates at equatorial port interspace after 10{sup 6} s of cooling time, 405 μSv/h has been obtained, of which 160 μSv/h (40%) are exclusively due to radiation cross-talk from a torus cryopump lower port. Equatorial port activation due to only “local neutrons” contributes 166 μSv/h at port interspace, showing that radiation cross-talk from such a lower port is a phenomenon comparable in magnitude to the neutron leakage though the equatorial port plug.

Evolving the JET virtual reality system for delivering the JET EP2 shutdown remote handling tasks

Energy Technology Data Exchange (ETDEWEB)

Williams, Adrian, E-mail: adrian.williams@oxfordtechnologies.co.uk [Oxford Technologies Ltd., 7 Nuffield Way, Abingdon, Oxon, OX14 1RJ (United Kingdom); JET-EFDA, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom); Sanders, Stephen [Oxford Technologies Ltd., 7 Nuffield Way, Abingdon, Oxon, OX14 1RJ (United Kingdom); JET-EFDA, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom); Weder, Gerard [Tree-C Technology BV, Buys Ballotstraat 8, 6716 BL Ede (Netherlands); JET-EFDA, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom); Bastow, Roger; Allan, Peter; Hazel, Stuart [CCFE, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom); JET-EFDA, Culham Science Centre, Abingdon, OX14 3DB (United Kingdom)

2011-10-15

The quality, functionality and performance of the virtual reality (VR) system used at JET for preparation and implementation of remote handling (RH) operations has been progressively enhanced since its first use in the original JET remote handling shutdown in 1998. As preparation began for the JET EP2 (Enhanced Performance 2) shutdown it was recognised that the VR system being used was unable to cope with the increased functionality and the large number of 3D models needed to fully represent the JET in-vessel components and tooling planned for EP2. A bespoke VR software application was developed in collaboration with the OEM, which allowed enhancements to be made to the VR system to meet the requirements of JET remote handling in preparation for EP2. Performance improvements required to meet the challenges of EP2 could not be obtained from the development of the new VR software alone. New methodologies were also required to prepare source, CATIA models for use in the VR using a collection of 3D software packages. In collaboration with the JET drawing office, techniques were developed within CATIA using polygon reduction tools to reduce model size, while retaining surface detail at required user limits. This paper will discuss how these developments have played an essential part in facilitating EP2 remote handling task development and examine their impact during the EP2 shutdown.

Evolving the JET virtual reality system for delivering the JET EP2 shutdown remote handling tasks

International Nuclear Information System (INIS)

Williams, Adrian; Sanders, Stephen; Weder, Gerard; Bastow, Roger; Allan, Peter; Hazel, Stuart

2011-01-01

The quality, functionality and performance of the virtual reality (VR) system used at JET for preparation and implementation of remote handling (RH) operations has been progressively enhanced since its first use in the original JET remote handling shutdown in 1998. As preparation began for the JET EP2 (Enhanced Performance 2) shutdown it was recognised that the VR system being used was unable to cope with the increased functionality and the large number of 3D models needed to fully represent the JET in-vessel components and tooling planned for EP2. A bespoke VR software application was developed in collaboration with the OEM, which allowed enhancements to be made to the VR system to meet the requirements of JET remote handling in preparation for EP2. Performance improvements required to meet the challenges of EP2 could not be obtained from the development of the new VR software alone. New methodologies were also required to prepare source, CATIA models for use in the VR using a collection of 3D software packages. In collaboration with the JET drawing office, techniques were developed within CATIA using polygon reduction tools to reduce model size, while retaining surface detail at required user limits. This paper will discuss how these developments have played an essential part in facilitating EP2 remote handling task development and examine their impact during the EP2 shutdown.

BEBP: An Poisoning Method Against Machine Learning Based IDSs

OpenAIRE

Li, Pan; Liu, Qiang; Zhao, Wentao; Wang, Dongxu; Wang, Siqi

2018-01-01

In big data era, machine learning is one of fundamental techniques in intrusion detection systems (IDSs). However, practical IDSs generally update their decision module by feeding new data then retraining learning models in a periodical way. Hence, some attacks that comprise the data for training or testing classifiers significantly challenge the detecting capability of machine learning-based IDSs. Poisoning attack, which is one of the most recognized security threats towards machine learning...

Pilot Operation of Ex-core Neutron Sensors of Divers Shutdown System (DSS) Unit 2 Ignalina NPP

International Nuclear Information System (INIS)

Jakshtonis, Z.; Krivoshei, G.

2006-01-01

The Ignalina Safety Assessment, which was completed in December 1996, recommended the installation of a diverse shutdown system on the 2nd unit at Ignalina. During the PPR-2004 in the DSS project are created two independent shutdown systems by separating the absorber rods into two independent groups as follows: 1. One system (designated AZ) consists of the existing 24 BAZ rods and 49 AZ/BSM rods that together are used for reliable reactor shutdown (including Control and Protection System (CPS) circuit voiding accident). This system performs the emergency protection function. 2. The other system (designated BSM) comprises the remaining absorber rods and the 49 AZ/BSM rods. Thus 49 AZ/BSM rods are actuated from AZ initiating equipment as well as from BSM initiating equipment. The BSM system performs the normal reactor shutdown function and is able to ensure long-term maintenance of the reactor in the sub-critical state. Along with implementation of DSS was modernized existing Emergency Process Protection System, which was divided into two independent Sets of initiating equipment. The DSS is independent and diverse initiating equipment from the existing 1st Set equipment; with each set having its own independent in-core and ex-core sensors for measurement of neutron flux and process parameters. The 2nd Set of initiating equipment for measuring ex-core neutron flux, was modernized with new design of 4 Ex-Core detectors each have a single low level neutron flux detector and two high range neutron detectors. They are comprising: 1. A fission chamber which operates in pulse mode to cover the low flux levels. 2. A compensated ionisation chamber in current mode to operate at high flux level. This detector is doubled to give a measurement of the axial deviation. Two detectors are enough to produce the axial power deviation. The results of testing and analysis of pilot operation of ex-core neutron sensors of DSS will be shown on the Report. (author)

Improving the reliability of stator insulation system in rotating machines

International Nuclear Information System (INIS)

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

1997-01-01

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

78 FR 38001 - Reconsideration of Certain Startup/Shutdown Issues: National Emission Standards for Hazardous Air...

Science.gov (United States)

2013-06-25

..., FRL-9827-1] RIN 2060-AR62 Reconsideration of Certain Startup/Shutdown Issues: National Emission... published in the Federal Register the proposed rule, ``Reconsideration of Certain New Source and Startup....'' That proposal opened for reconsideration certain issues, including those related to startup and...

The feasibility study of using deuterated gadolinium nitrate for moderator-poisoned shutdown and excess reactivity control in CANDU reactors

International Nuclear Information System (INIS)

Li, J.; Everatt, A.

2006-01-01

Gadolinium nitrate is used in CANDU stations as moderator poison for reactor shutdowns and excess reactivity control. The use of the light-water hydrate introduces significant quantities of light water into the moderator system, which must be removed from the moderator by periodically upgrading the moderator (isotopic maintenance). The benefit of using a deuterated gadolinium nitrate would be a higher moderator isotopic and/or a lesser isotopic maintenance requirement. This study evaluated the economics of using deuterated gadolinium nitrate, as opposed to the light-water hydrate, for moderator-poisoned shutdowns and excess reactivity control in CANDU-6 reactors. Normal gadolinium nitrate (i.e., the light-water hydrate) is available from suppliers at ∼125 $/kg. Supplier quotes for deuterated gadolinium nitrate ranged from 1900 to 4000 $/kg. To examine the possibility of producing deuterated gadolinium nitrate in-house at a lower cost than commercially available, a three-stage dissolution/evaporation manufacturing process was conceived and costed. Depending on the assumed demand for the product (i.e., the number of reactors adopting the use of the product) and the capital recovery period, the estimated unit cost for the dissolution/evaporation process ranged from 730 to 2500 $/kg. The determination of economic benefit from using deuterated gadolinium nitrate in existing CANDU stations was based on the cost savings resulting from a higher fuel burn-up (i.e., the higher moderator isotopic would give a higher fuel burn-up). The net benefit of using deuterated gadolinium nitrate for most CANDU stations was determined to be marginal (i.e., <20 k$/a). Only for those CANDU stations where the moderator isotopic was relatively low (e.g., 99.85 wt%) was there a potential significant benefit (20-100 k$/a). However, if the reason for the low moderator isotopic is a relatively high moderator light-water ingress rate from sources other than the use of the light-water hydrate

Machinability of cast commercial titanium alloys.

Science.gov (United States)

Watanabe, I; Kiyosue, S; Ohkubo, C; Aoki, T; Okabe, T

2002-01-01

This study investigated the machinability of cast orthopedic titanium (metastable beta) alloys for possible application to dentistry and compared the results with those of cast CP Ti, Ti-6Al-4V, and Ti-6Al-7Nb, which are currently used in dentistry. Machinability was determined as the amount of metal removed with the use of an electric handpiece and a SiC abrasive wheel turning at four different rotational wheel speeds. The ratios of the amount of metal removed and the wheel volume loss (machining ratio) were also evaluated. Based on these two criteria, the two alpha + beta alloys tested generally exhibited better results for most of the wheel speeds compared to all the other metals tested. The machinability of the three beta alloys employed was similar or worse, depending on the speed of the wheel, compared to CP Ti. Copyright 2002 Wiley Periodicals, Inc.

Design, construction, operation, shutdown and surveillance of repositories for solid radioactive wastes in shallow ground

International Nuclear Information System (INIS)

1984-01-01

This report is a part of the IAEA publications under its Programme on Underground Disposal of Radioactive Wastes and is addressed to administrative and technical authorities and specialists who consider the shallow-ground disposal of low- and intermediate-level solid radioactive wastes of short half-lives. The report emphasizes the technological aspects, however it briefly discusses the safety philosophy and regulatory considerations too. The design, construction, operation, shutdown and surveillance of the repositories in shallow ground are considered in some detail, paying special attention to their interrelated aspects. In particular, a review is given of the following aspects: main design and construction considerations in relation to the natural features of the site; design and construction aspects during the repository development process; activities related to operational and post-operational stages of the repository; major steps in repository operation and essential activities in shutdown and operational and post-operational surveillance

The analysis of pressurizer safety valve stuck open accident for low power and shutdown PSA

Energy Technology Data Exchange (ETDEWEB)

Lim, Ho Gon; Park, Jin Hee; Jang, Seong Chul; Kim, Tae Woon

2005-01-01

The PSV (Pressurizer Safety Valve) popping test carried out practically in the early phase of a refueling outage has a little possibility of triggering a test-induced LOCA due to a PSV not fully closed or stuck open. According to a KSNP (Korea Standard Nuclear Power Plant) low power and shutdown PSA (Probabilistic Safety Assessment), the failure of a HPSI (High Pressure Safety Injection) following a PSV stuck open was identified as a dominant accident sequence with a significant contribution to low power and shutdown risks. In this study, we aim to investigate the consequences of the NPP for the various accident sequences following the PSV stuck open as an initiating event through the thermal-hydraulic system code calculations. Also, we search the accident mitigation method for the sequence of HPSI failure, then, the applicability of the method is verified by the simulations using T/H system code.

Safe shutdown of Defense Program facilities at the Mound Plant, Miamisburg, Ohio

International Nuclear Information System (INIS)

Anderson, H.F.; Bantz, P.D.; Luthy, D.F.

1996-01-01

The Mound Plant was one of several production sites in the US Department of Energy's Defense Programs (DP) Weapons Complex. As a result of the downsizing of the weapons program, certain operations at Mound are being transferred to other DOE sites and the DP buildings at Mound are being shutdown. The objectives of the program are to reduce the hazardous and financial liabilities to DOE and to foster the reuse of facilities for economic development. The overall program is described. The process began with the categorization of excess DP buildings into three groups depending on their anticipated future use. The draft DOE/EM-60 Acceptance Criteria were used to develop a detailed shutdown checklist as the foundation of the process. The overall program budget, schedule, ad options for disposition of materials and components is presented. Accomplishments in FY94 and FY95 are described. By the end of FY95, all excess energetic materials and components, all excess chemicals (from non-radiation areas) and significant amounts of radioactive materials have been removed from the site. By the end of FY95, 47 of the 72 buildings in the program have been taken through all ten of the draft EM-60 acceptance criteria. Lessons learned, based on experience at Mound to date, are summarized

Reliability modeling of Clinch River breeder reactor electrical shutdown systems

International Nuclear Information System (INIS)

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

1974-01-01

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

Running and machine studies in 1990

International Nuclear Information System (INIS)

1991-03-01

This annual report described the GANIL performance and machine studies. During the year 1990, the machine has been operated for 36 weeks divided into periods of 5, 6 or 7 weeks; consequently the number of beam setting up has been reduced. From 5682 hours of scheduled beam 3239 hours have been delivered on target. Very heavy ions (Pb, U) are now accelerated owing to the OAE modification. Many experiments have been completed with the new medium energy beam facility. The machine studies were devoted to the development ot the following items: production of 157 Gd 19+ ions, acceleration of 238 U 59+ at 24 MeV/u, SSC1 orbit precession, charge state distribution and energy spread after stripping [fr

Display-And-Alarm Circuit For Accelerometer

Science.gov (United States)

Bozeman, Richard J., Jr.

1995-01-01

Compact accelerometer assembly consists of commercial accelerometer retrofit with display-and-alarm circuit. Provides simple means for technician attending machine to monitor vibrations. Also simpifies automatic safety shutdown by providing local alarm or shutdown signal when vibration exceeds preset level.

Summary of Information Presented at an NRC-Sponsored Low-Power Shutdown Public Workshop, April 27, 1999, Rockville, Maryland

International Nuclear Information System (INIS)

Wheeler, Timothy A.; Whitehead, Donnie W.; Lois, Erasmia

1999-01-01

This report summarizes a public workshop that was held on April 27, 1999, in Rockville, Maryland. The workshop was conducted as part of the US Nuclear Regulatory Commission's (NRC) efforts to further develop its understanding of the risks associated with low power and shutdown operations at US nuclear power plants. A sufficient understanding of such risks is required to support decision-making for risk-informed regulation, in particular Regulatory Guide 1.174, and the development of a consensus standard. During the workshop the NRC staff discussed and requested feedback from the public (including representatives of the nuclear industry, state governments, consultants, private industry, and the media) on the risk associated with low-power and shutdown operations

Summary of Information Presented at an NRC-Sponsored Low-Power Shutdown Public Workshop, April 27, 1999, Rockville, Maryland

Energy Technology Data Exchange (ETDEWEB)

Wheeler, Timothy A.; Whitehead, Donnie W.; Lois, Erasmia

1999-07-01

This report summarizes a public workshop that was held on April 27, 1999, in Rockville, Maryland. The workshop was conducted as part of the US Nuclear Regulatory Commission's (NRC) efforts to further develop its understanding of the risks associated with low power and shutdown operations at US nuclear power plants. A sufficient understanding of such risks is required to support decision-making for risk-informed regulation, in particular Regulatory Guide 1.174, and the development of a consensus standard. During the workshop the NRC staff discussed and requested feedback from the public (including representatives of the nuclear industry, state governments, consultants, private industry, and the media) on the risk associated with low-power and shutdown operations.

Event data collection and database development during plant shutdown and low power operations at domestic and foreign reactors

International Nuclear Information System (INIS)

Kim, T. Y.; Park, J. H.; Han, S. J.; Im, H. K.; Jang, S. C.

2003-01-01

To reduce conservatism and to obtain completeness for Low Power and ShutDown(LPSD) PSA of nuclear plants, total of 625 event data have collected during shutdown and low power operations which have occurred during about 30 years at nuclear power plants of USA and European countries including 2 domestic events. To utilize efficiently these event data, a database program which is called LEDB (Low power and shutdown Event Database) was developed and all the event data collected were inserted in that program. By reviewing and analyzing these event data various way, a lot of very useful insights and ideas for preventing similar events from reoccurrence in domestic nuclear power plants can be obtained

Design Options for Thermal Shutdown Circuitry with Hysteresis Width Independent on the Activation Temperature

Directory of Open Access Journals (Sweden)

PLESA, C.-S.

2017-02-01

Full Text Available This paper presents several design options for implementing a thermal shutdown circuit with hysteretic characteristic, which has two special features: a programmable activation temperature (the upper trip point of the characteristic and a hysteresis width largely insensitive to the actual value of the activation temperature and to variations of the supply voltage. A fairly straightforward architecture is employed, with the hysteresis implemented by a current source enabled by the output of the circuit. Four possible designs are considered for this current source: VBE/R, modified-VBE/R, Widlar and a peaking current source tailored for this circuit. First, a detailed analytical analysis of the circuit implemented with these current sources is performed; it indicates the one best suited for this application and provides key sizing equations. Next, the chosen current source is employed to design the thermal shutdown protection of an integrated Low-Dropout Voltage Regulator (LDO for automotive applications. Simulation results and measurements performed on the silicon implementation fully validate the design. Moreover, they compare favorably with the performance of similar circuits reported recently.

Machine rates for selected forest harvesting machines

Science.gov (United States)

R.W. Brinker; J. Kinard; Robert Rummer; B. Lanford

2002-01-01

Very little new literature has been published on the subject of machine rates and machine cost analysis since 1989 when the Alabama Agricultural Experiment Station Circular 296, Machine Rates for Selected Forest Harvesting Machines, was originally published. Many machines discussed in the original publication have undergone substantial changes in various aspects, not...

78 FR 60260 - Order of the Commodity Futures Trading Commission Relating to the Continuation, Shutdown, and...

Science.gov (United States)

2013-10-01

..., cyber security incidents or financial emergencies throughout a lapse in appropriations. C. Extension of...) price discovery; (4) sound risk management practices; and (5) other public interest considerations. The... malfunctions, cyber-security incidents, and financial emergencies shall continue during a shutdown. The...

78 FR 79709 - Duke Energy Florida, Inc., Crystal River Unit 3 Nuclear Generating Plant Post-Shutdown...

Science.gov (United States)

2013-12-31

... NUCLEAR REGULATORY COMMISSION [Docket No. 50-302; NRC-2013-0283] Duke Energy Florida, Inc., Crystal River Unit 3 Nuclear Generating Plant Post-Shutdown Decommissioning Activities Report AGENCY: Nuclear Regulatory Commission (NRC). ACTION: Notice of receipt; availability; public meeting; and request...

Performance of the Liquid Argon and Tile Calorimeters during the 2012 data taking period

CERN Document Server

Ilic, N; The ATLAS collaboration

2013-01-01

ATLAS operated with an excellent efficiency during 2012 data taking period, recording an integrated luminosity of 21.6 fb-1 at √s = 8 TeV during the p-p run. The Liquid Argon and Tile Calorimeter contributed to this effort by operating with a good data quality efficiency of 99.1% and 99.6% respectively. This poster presents the overall status, operations, performance and shutdown plans for the calorimeters.

Preliminary Calculations of Shutdown Dose Rate for the CTS Diagnostics System

DEFF Research Database (Denmark)

Klinkby, Esben Bryndt; Nonbøl, Erik; Lauritzen, Bent

2015-01-01

DTU and IST 2 are partners in the design of a collective Thomson Scattering (CTS) diagnostics for ITER through a contract with F4E. The CTS diagnostic utilizes probing radiation of ~60 GHz emitted into the plasma and, using a mirror, collects the scattered radiation by an array of receivers. Having...... on supplying input which affect the system design. Examples include: - Heatloads on plasma facing mirrors and preliminary stress and thermal analysis - Port plug cooling requirements and it's dependence on system design (in particular blanket cut-out) - Shutdown dose-rate calculations (relative analysis...

Decomposition of the Strategic Plan for Restructuring a Machine-Building Enterprise in View of Continuity of the Plans for Adjacent Periods

Directory of Open Access Journals (Sweden)

Kozyr-Chepurna Mariia A.

2017-09-01

Full Text Available The aim of the article is to practically approve the authors’ multi-level hierarchical approach to the strategic planning of industrial enterprise restructuring using the example of solving the problem of disaggregating the strategic plan for restructuring a machine-building enterprise of the electrical industry providing for organization of production of railroad freight cars at the enterprise. Besides, there demonstrated the effectiveness of the mechanisms of coordinating the plans for adjacent hierarchical and time periods included in the corresponding mathematical support. In the course of the practical approval, different variants of formulating the problem of decomposing the strategic plan into plans of lower hierarchical levels differing in terms of coordination of the plans of adjacent hierarchical levels and adjacent planning periods are considered, and the solutions of corresponding optimal planning problems are analyzed. It is shown that the developed methodological approach, which is based on the methods of statistical optimization, demonstrates quite satisfactory performance characteristics in solving the problem of coordinating the plans of adjacent time periods in the mode of sliding planning in the process of decomposition of the strategic plan into lower-level plans.

Nuclear reactor shutdown control rod assembly

International Nuclear Information System (INIS)

Bilibin, K.

1988-01-01

This patent describes a nuclear reactor having a reactor core and a reactor coolant flowing therethrough, a temperature responsive, self-actuated nuclear reactor shutdown control rod assembly, comprising: an upper drive line terminating at its lower end with a substantially cylindrical wall member having inner and outer surfaces; a lower drive line having a lower end adapted to be attached to a neutron absorber; a ring movable disposed about the outer surface of the wall member of the upper drive line; thermal actuation means adapted to be in heat exchange relationship with coolant in an associated reactor core and in contact with the ring, and balls located within the openings in the upper drive line. When reactor coolant approaches a predetermined design temperature the actuation means moves the ring sufficiently so that the balls move radially out from the recess and into the space formed by the second portion of the ring thereby removing the vertical support for the lower drive line such that the lower drive line moves downwardly and inserts an associated neutron absorber into an associated reactor core resulting in automatic reduction of reactor power

Reserves for shutdown/dismantling and disposal in nuclear technology. Theses and recommendations on reform options; Rueckstellungen fuer Stilllegung/Rueckbau und Entsorgung im Atombereich. Thesen und Empfehlungen zu Reformoptionen

Energy Technology Data Exchange (ETDEWEB)

Meyer, Bettina [Forum Oekologisch-Soziale Marktwirtschaft e.V. (FOeS), Berlin (Germany). Green Budget Germany (GBG)

2012-04-11

The study on reserves for shutdown, dismantling and disposal of nuclear facilities covers the following topics: cost for shutdown, dismantling and disposal and amount and transparency of nuclear reserves, solution by y stock regulated by public law for long-term liabilities, and improvement of the protection in the event of insolvency for the remaining EVU reserves for short- and intermediate-term liabilities. The appendix includes estimations and empirical values for the cost of shutdown and dismantling, estimation of disposal costs, and a summary of Swiss studies on dismantling and disposal and transfer to Germany.

77 FR 72294 - Reconsideration of Certain New Source and Startup/Shutdown Issues: National Emission Standards...

Science.gov (United States)

2012-12-05

... ENVIRONMENTAL PROTECTION AGENCY 40 CFR Parts 60 and 63 [EPA-HQ-OAR-2009-0234; EPA-HQ-OAR-2011-0044; FRL-9733-2] RIN 2060-AR62 Reconsideration of Certain New Source and Startup/Shutdown Issues: National Emission Standards for Hazardous Air Pollutants From Coal- and Oil-Fired Electric Utility Steam Generating...

Modelling of liquid injection shutdown system (LISS) in ACR-1000

International Nuclear Information System (INIS)

Boubcher, M.; Colton, A.; Donnelly, J.V.

2008-01-01

Modelling of the Liquid Injection Shutdown System (LISS) in the ACR-1000 reactor core must account for the major phenomena that occur following its activation, namely the moderator hydraulics and core neutronics. The former requires modelling of the poison volumes, their time of entry into the reactor, and their propagation into the moderator after emission from the nozzle. The latter requires the reactivity worth of varying volumes and geometries of poisoned moderator fluid in order to simulate the reactivity effect of the injected poison. The time-dependent poison map is generated from hydraulic calculations, and then the neutronics data for standard geometries and concentrations is constructed using DRAGON. (author)

High level waste facilities - Continuing operation or orderly shutdown

International Nuclear Information System (INIS)

Decker, L.A.

1998-04-01

Two options for Environmental Impact Statement No action alternatives describe operation of the radioactive liquid waste facilities at the Idaho Chemical Processing Plant at the Idaho National Engineering and Environmental Laboratory. The first alternative describes continued operation of all facilities as planned and budgeted through 2020. Institutional control for 100 years would follow shutdown of operational facilities. Alternatively, the facilities would be shut down in an orderly fashion without completing planned activities. The facilities and associated operations are described. Remaining sodium bearing liquid waste will be converted to solid calcine in the New Waste Calcining Facility (NWCF) or will be left in the waste tanks. The calcine solids will be stored in the existing Calcine Solids Storage Facilities (CSSF). Regulatory and cost impacts are discussed

An investigation of scramming the outer shutdown rods of the ANS with no reversal of flow in the manifold inlet lines

International Nuclear Information System (INIS)

Morsk, K.

1992-10-01

This report provides calculations and calculation checks on the outer shutdown system, consisting of eight shutdown rods located on the outside of the core. The function of the system is to scram the reactor, or to break the chain reaction of the fission process. The shutdown rods are clad with a neutron-absorbing material (i.e., hafnium) to achieve scram. During normal operation, the outer shutdown rods (Fig. 1) are in a nonscram, withdrawn position. This means that they are not close enough to the core to absorb a significant number of the neutrons that cause the fission process. In the case of a malfunction or an emergency, the outer control rods are moved to a position near the core. The outer shutdown system is operated with the use of springs and hydraulics. During normal operation, a constant flow of heavy water is circulated through the reflector vessel. A part of this flow provides a pressure high enough to keep the rods in their withdrawn or upper position, a nonscram status. If any signs of abnormal operation occur, the valves in the hydraulic system cut off the flow, and the springs push the rods into the scram position, stopping the chain reaction. Once the flow is restarted, the rods can be withdrawn to the nonscram position. Calculations of the mass of the outer control rod, the scram spring data, and the hydraulic pressure to hold the rods in the withdrawn position have been checked. In the case of a malfunction of the flow/pressure relief valves, a calculation was needed to show that the scram time would not exceed the time allowed. The scram time has been determined based on different values of the rod insertion length and the outside radius of the annulus was calculated. The effective force pushing the rod into the scram position, the rate of acceleration, and the actual scram time was then determined

Ex-vivo machine perfusion for kidney preservation.

Science.gov (United States)

Hamar, Matyas; Selzner, Markus

2018-06-01

Machine perfusion is a novel strategy to decrease preservation injury, improve graft assessment, and increase organ acceptance for transplantation. This review summarizes the current advances in ex-vivo machine-based kidney preservation technologies over the last year. Ex-vivo perfusion technologies, such as hypothermic and normothermic machine perfusion and controlled oxygenated rewarming, have gained high interest in the field of organ preservation. Keeping kidney grafts functionally and metabolically active during the preservation period offers a unique chance for viability assessment, reconditioning, and organ repair. Normothermic ex-vivo kidney perfusion has been recently translated into clinical practice. Preclinical results suggest that prolonged warm perfusion appears superior than a brief end-ischemic reconditioning in terms of renal function and injury. An established standardized protocol for continuous warm perfusion is still not available for human grafts. Ex-vivo machine perfusion represents a superior organ preservation method over static cold storage. There is still an urgent need for the optimization of the perfusion fluid and machine technology and to identify the optimal indication in kidney transplantation. Recent research is focusing on graft assessment and therapeutic strategies.

[A new machinability test machine and the machinability of composite resins for core built-up].

Science.gov (United States)

Iwasaki, N

2001-06-01

A new machinability test machine especially for dental materials was contrived. The purpose of this study was to evaluate the effects of grinding conditions on machinability of core built-up resins using this machine, and to confirm the relationship between machinability and other properties of composite resins. The experimental machinability test machine consisted of a dental air-turbine handpiece, a control weight unit, a driving unit of the stage fixing the test specimen, and so on. The machinability was evaluated as the change in volume after grinding using a diamond point. Five kinds of core built-up resins and human teeth were used in this study. The machinabilities of these composite resins increased with an increasing load during grinding, and decreased with repeated grinding. There was no obvious correlation between the machinability and Vickers' hardness; however, a negative correlation was observed between machinability and scratch width.

Maintenance of shutdown system in the reactor core to minimize the radioactive waste generation

International Nuclear Information System (INIS)

Ponzoni Filho, P.; Fernandes, V.B.

1988-01-01

This paper recommends a modification on the actual strategy of going from Cold-Shutdown to Critical, that will save about 6000 liter of boric acid and 30,000 liters of demineralized water for each reactor criticalization. This strategy will reduce the radioactive waste disposal volume to only about 5% of what would be generated following the actual strategy. (author) [pt

Recent experience about the influence of primary coolant and shutdown chemistry on cobalt activity at Beznau NPP

International Nuclear Information System (INIS)

Mailand, I.; Venz, H.

2007-01-01

The Beznau nuclear power plant comprises two identical 380 MWe PWR units, commissioned in 1969 and 1971. The surfaces of the new steam generator tube material, Inconel 690, are the main source of 58 Co. The 60 Co originates predominantly from the Cobalt alloy, Stellite, which is installed in valves and pump bearings because of the very good hardness of this material. By means of optimised shutdown chemistry it is possible to reduce the amount of NiO on the fuel rods, leading to reduced Co-58 peaks in subsequent cycles. The optimised shutdown chemistry during the past few years and especially the strict separation of acid-reducing phase from the acid-oxidising phase as well as the results of studies and the resulting operational experiences are important basics for the actual operation mode of the Beznau NPP. (orig.)

Pricing and availability intervention in vending machines at four bus garages.

Science.gov (United States)

French, Simone A; Hannan, Peter J; Harnack, Lisa J; Mitchell, Nathan R; Toomey, Traci L; Gerlach, Anne

2010-01-01

To evaluate the effects of lowering prices and increasing availability on sales of healthy foods and beverages from 33 vending machines in 4 bus garages as part of a multicomponent worksite obesity prevention intervention. Availability of healthy items was increased to 50% and prices were lowered at least 10% in the vending machines in two metropolitan bus garages for an 18-month period. Two control garages offered vending choices at usual availability and prices. Sales data were collected monthly from each of the vending machines at the four garages. Increases in availability to 50% and price reductions of an average of 31% resulted in 10% to 42% higher sales of the healthy items. Employees were mostly price responsive for snack purchases. Greater availability and lower prices on targeted food and beverage items from vending machines was associated with greater purchases of these items over an 18-month period. Efforts to promote healthful food purchases in worksite settings should incorporate these two strategies.

Shutdown dose rate contribution from diagnostics in ITER upper port 18

Energy Technology Data Exchange (ETDEWEB)

Cheon, M.S., E-mail: munseong@nfri.re.kr [National Fusion Research Institute, Daejeon (Korea, Republic of); Pak, S.; An, Y.H.; Seon, C.R.; Lee, H.G. [National Fusion Research Institute, Daejeon (Korea, Republic of); Bertalot, L.; Krasilnikov, V. [ITER Organization, St Paul-lez-Durance (France); Zvonkov, A. [Agency ITER-RF, Moscow (Russian Federation)

2016-11-01

Highlights: • The Shutdown Dose Rate in the interspace of ITER upper port 18 was evaluated. • VUV spectrometer is the dominant contributor to the average SDR. • The existence and size of the blanket cooling pipes impacts significantly on SDR. - Abstract: D-T operation of ITER plasma will produce high-energy fusion neutrons those can activate materials around the place where human-access is necessary. The interspace of the diagnostic port is one of the area where human-access is necessary for the maintenance of diagnostic systems installed at the port, so it is important to evaluate a dose rate of the interspace area in order to comply with ALARA principle. The shutdown dose rate (SDR) in the interspace of ITER upper port 18 was evaluated by the Direct 1-Step (D1S) method using MCNP5 code. This port contains three diagnostics: Vacuum Ultra-Violet (VUV) Spectrometer, Neutron Activation System (NAS), and Upper Vertical Neutron Camera (UVNC). The contribution of each diagnostic in the port was evaluated by running separate upper port MCNP models those contain individual diagnostic only, and the total dose rate contribution was evaluated with the model which was fully integrated with all the diagnostics. The effect of the opening around the upper port plug and of the other ports was also investigated. The purpose of this assessment is to provide the shielding design basis for the preliminary design of the diagnostic integration in the port. The method and result of the calculation will be presented in this paper.

Radiologic states of the WWR-S Bucharest Reactor following definitive shutdown

International Nuclear Information System (INIS)

Garlea, C.; Kelerman, C.; Mocioiu, D.; Garlea, I.

2001-01-01

The definitive shutdown of a reactor raises problems related to the management of the radioactive inventory. To define the radioactive inventory contained in the burned nuclear fuel and in the neutron activated structural materials computation methods are to be used. Besides the radioactive inventory contained in the main block of the reactor, the one due to the primary circuit contaminated mainly with fission products and corrosion products activated in the reactor core, transported and deposed on the components of the cooling primary circuit should be added. Also another component of the radioactive inventory intervenes, namely, the one due to the contamination of the technological rooms used for various operations the nuclear activities (hot cells, pump room, reactor hall, passage ways to the hot cells and for radioactive source, radioisotope and radioactive waste transport). The activities which made used of the neutron and gamma fluxes for radioisotope production, materials irradiation, research, component testing, resulted in radioactive waste, technological or accidental contaminations of the technological rooms of the reactor. Inspections and current repair interventions resulted also in radioactive waste an contaminations. Consequently systematic measurements with qualified equipment dedicated to alpha, beta, gamma contamination measurements as well as to dose rates determinations for the personnel exposed are necessary. Irrespective of the duration of the reactor conservation or shutdown, the radiologic monitoring should continue. This work presents the results obtained by the research group 'Restoration of Nuclear Sites', working with the IFIN-HH, regarding both the radioactive inventory calculation and measurements of contamination of technological rooms and environment in the reactor vicinity

Novel hybrid Monte Carlo/deterministic technique for shutdown dose rate analyses of fusion energy systems

International Nuclear Information System (INIS)

Ibrahim, Ahmad M.; Peplow, Douglas E.; Peterson, Joshua L.; Grove, Robert E.

2014-01-01

Highlights: •Develop the novel Multi-Step CADIS (MS-CADIS) hybrid Monte Carlo/deterministic method for multi-step shielding analyses. •Accurately calculate shutdown dose rates using full-scale Monte Carlo models of fusion energy systems. •Demonstrate the dramatic efficiency improvement of the MS-CADIS method for the rigorous two step calculations of the shutdown dose rate in fusion reactors. -- Abstract: The rigorous 2-step (R2S) computational system uses three-dimensional Monte Carlo transport simulations to calculate the shutdown dose rate (SDDR) in fusion reactors. Accurate full-scale R2S calculations are impractical in fusion reactors because they require calculating space- and energy-dependent neutron fluxes everywhere inside the reactor. The use of global Monte Carlo variance reduction techniques was suggested for accelerating the R2S neutron transport calculation. However, the prohibitive computational costs of these approaches, which increase with the problem size and amount of shielding materials, inhibit their ability to accurately predict the SDDR in fusion energy systems using full-scale modeling of an entire fusion plant. This paper describes a novel hybrid Monte Carlo/deterministic methodology that uses the Consistent Adjoint Driven Importance Sampling (CADIS) method but focuses on multi-step shielding calculations. The Multi-Step CADIS (MS-CADIS) methodology speeds up the R2S neutron Monte Carlo calculation using an importance function that represents the neutron importance to the final SDDR. Using a simplified example, preliminary results showed that the use of MS-CADIS enhanced the efficiency of the neutron Monte Carlo simulation of an SDDR calculation by a factor of 550 compared to standard global variance reduction techniques, and that the efficiency enhancement compared to analog Monte Carlo is higher than a factor of 10,000

Testing Quality and Metrics for the LHC Magnet Powering System throughout Past and Future Commissioning

OpenAIRE

Anderson, D; Audrain, M; Charifoulline, Z; Dragu, M; Fuchsberger, K; Garnier, JC; Gorzawski, AA; Koza, M; Krol, K; Rowan, S; Stamos, K; Zerlauth, M

2014-01-01

The LHC magnet powering system is composed of thousands of individual components to assure a safe operation when operating with stored energies as high as 10GJ in the superconducting LHC magnets. Each of these components has to be thoroughly commissioned following interventions and machine shutdown periods to assure their protection function in case of powering failures. As well as having dependable tracking of test executions it is vital that the executed commissioning steps and applied anal...

Site Characterization Report ORGDP Diffusion Facilities Permanent Shutdown K-700 Power House and K-27 Switch Yard/Switch House

Energy Technology Data Exchange (ETDEWEB)

Thomas R.J., Blanchard R.D.

1988-06-13

The K-700 Power House area, initially built to supply power to the K-25 gaseous diffusion plant was shutdown and disassembled in the 1960s. This shutdown was initiated by TVA supplying economical power to the diffusion plant complex. As a result of world wide over production of enriched, reactor grade U{sup 235}, the K-27 switch yard and switch house area was placed in standby in 1985. Subsequently, as the future production requirements decreased, the cost of production increased and the separation technologies for other processes improved, the facility was permanently shutdown in December, 1987. This Site Characterization Report is a part of the FY-88 engineering Feasibility Study for placing ORGDP Gaseous Diffusion Process facilities in 'Permanent Shutdown'. It is sponsored by the Department of Energy through Virgil Lowery of Headquarters--Enrichment and through Don Cox of ORO--Enrichment Operations. The primary purpose of these building or site characterization reports is to document, quantify, and map the following potential problems: Asbestos; PCB containing fluids; Oils, coolants, and chemicals; and External contamination. With the documented quantification of the concerns (problems) the Engineering Feasibility Study will then proceed with examining the potential solutions. For this study, permanent shutdown is defined as the securing and/or conditioning of each facility to provide 20 years of safe service with minimal expenditures and, where feasible, also serving DOE's needs for long-term warehousing or other such low-risk use. The K-700 power house series of buildings were either masonry construction or a mix of masonry and wood. The power generating equipment was removed and sold as salvage in the mid 1960s but the buildings and auxiliary equipment were left intact. The nine ancillary buildings in the power house area use early in the Manhattan Project for special research projects, were left intact minus the original special equipment

Results of TMX operations: January-July 1980

International Nuclear Information System (INIS)

Correll, D.L.; Drake, R.P.

1980-01-01

This interim report summarizes results from the Tandem Mirror Experiment (TMX) during the period January to July 1980 and describes the physics experiments, the machine operation, and the diagnostics that were added to TMX during this period. This operating period followed the initial proof-of-principle TMX experiments and predated the ongoing final experiments preceding TMX shutdown for modification to TMX Upgrade. The results described in this report include measurements of plasma parameters and plasma behavior which confirm the initial TMX results that demonstrated that the tandem mirror configuration can be generated and sustained by neutral beam injection and that the tandem mirror configuration improves confinement of magnetic mirror systems

Machine-z: Rapid Machine-Learned Redshift Indicator for Swift Gamma-Ray Bursts

Science.gov (United States)

Ukwatta, T. N.; Wozniak, P. R.; Gehrels, N.

2016-01-01

Studies of high-redshift gamma-ray bursts (GRBs) provide important information about the early Universe such as the rates of stellar collapsars and mergers, the metallicity content, constraints on the re-ionization period, and probes of the Hubble expansion. Rapid selection of high-z candidates from GRB samples reported in real time by dedicated space missions such as Swift is the key to identifying the most distant bursts before the optical afterglow becomes too dim to warrant a good spectrum. Here, we introduce 'machine-z', a redshift prediction algorithm and a 'high-z' classifier for Swift GRBs based on machine learning. Our method relies exclusively on canonical data commonly available within the first few hours after the GRB trigger. Using a sample of 284 bursts with measured redshifts, we trained a randomized ensemble of decision trees (random forest) to perform both regression and classification. Cross-validated performance studies show that the correlation coefficient between machine-z predictions and the true redshift is nearly 0.6. At the same time, our high-z classifier can achieve 80 per cent recall of true high-redshift bursts, while incurring a false positive rate of 20 per cent. With 40 per cent false positive rate the classifier can achieve approximately 100 per cent recall. The most reliable selection of high-redshift GRBs is obtained by combining predictions from both the high-z classifier and the machine-z regressor.

Electrospun Nanofibers for Sandwiched Polyimide/Poly (vinylidene fluoride)/Polyimide Separators with the Thermal Shutdown Function

International Nuclear Information System (INIS)

Wu, Dezhi; Shi, Chuan; Huang, Shaohua; Qiu, Xiaochun; Wang, Huan; Zhan, Zhan; Zhang, Peng; Zhao, Jinbao; Sun, Daoheng; Lin, Liwei

2015-01-01

Nanofibers fabricated by the electrospinning process have been used to construct sandwich-type Polyimide/Poly (vinylidene fluoride)/Polyimide (PI/PVDF/PI) separators with the thermal shutdown function for lithium ion batteries. This architecture uses the good thermal stability of PI as the top and bottom structure layers. Under high temperature operations, the middle layer made of PVDF nanofibers can melt and form a pore-free film to shut down the battery operation. The electrolyte uptake and ionic conductivity of the PI/PVDF/PI separator are superior to those of commercial polyolefin separators at 476% and 3.46 mS cm −1 , respectively, resulting better battery performances in terms of impedance, discharge capacity and cycle life. Under high temperature treatments above 170 °C, the self-shutdown function of the PI/PVDF/PI has been observed within 10 minutes, which could serve as the safety mechanism to defend the thermal runaway issue of lithium ion batteries. The effects of heating temperature and different time on the morphologies of each layer and electrolyte uptake of the separator are characterized as well

A Comparison of Machine Learning Approaches for Corn Yield Estimation

Science.gov (United States)

Kim, N.; Lee, Y. W.

2017-12-01

Machine learning is an efficient empirical method for classification and prediction, and it is another approach to crop yield estimation. The objective of this study is to estimate corn yield in the Midwestern United States by employing the machine learning approaches such as the support vector machine (SVM), random forest (RF), and deep neural networks (DNN), and to perform the comprehensive comparison for their results. We constructed the database using satellite images from MODIS, the climate data of PRISM climate group, and GLDAS soil moisture data. In addition, to examine the seasonal sensitivities of corn yields, two period groups were set up: May to September (MJJAS) and July and August (JA). In overall, the DNN showed the highest accuracies in term of the correlation coefficient for the two period groups. The differences between our predictions and USDA yield statistics were about 10-11 %.

Development of Abnormal Operating Strategies for Loss of Ultimate Heat Sink (LOUHS) at Shutdown Mode in Westinghouse Type Nuclear Power Plant

Energy Technology Data Exchange (ETDEWEB)

Yoon, Duk-Joo; Lee, Seung-Chan; Sung, Je-Joong; Ha, Sang Jun [KHNP CRI, Daejeon (Korea, Republic of); Hwang, Su-Hyun [FNC Tech. Co., Yongin (Korea, Republic of)

2016-10-15

Loss of all AC power is classified as one of multiple failure accident by regulatory guide of Korean accident management program. Therefore we need develop strategies for the abnormal operating procedure both of power operating and shutdown mode. This paper developed abnormal operating guideline for loss of all AC power by analysis of accident scenario in pressurized water reactor. This paper analyzed the extended SBO in shutdown operating mode and developed the operating strategy of the abnormal operation procedure. Operator action for the emergency are not required to take in 500 minutes and 60 minutes in intact and opened RCS state respectively.

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

The Machine within the Machine

CERN Multimedia

Katarina Anthony

2014-01-01

Although Virtual Machines are widespread across CERN, you probably won't have heard of them unless you work for an experiment. Virtual machines - known as VMs - allow you to create a separate machine within your own, allowing you to run Linux on your Mac, or Windows on your Linux - whatever combination you need.   Using a CERN Virtual Machine, a Linux analysis software runs on a Macbook. When it comes to LHC data, one of the primary issues collaborations face is the diversity of computing environments among collaborators spread across the world. What if an institute cannot run the analysis software because they use different operating systems? "That's where the CernVM project comes in," says Gerardo Ganis, PH-SFT staff member and leader of the CernVM project. "We were able to respond to experimentalists' concerns by providing a virtual machine package that could be used to run experiment software. This way, no matter what hardware they have ...

On the principles of the determination of the safe shut-down earthquake for nuclear power plants in Austria

International Nuclear Information System (INIS)

Drimmel, J.

1976-01-01

At present no legal guide lines exist in Austria for the determination of the Safe Shut-Down Earthquake. According to experience, the present requirements for a nuclear power plant site are the following: It must be free of marked tectonic faults and it must never have been situated within the epicentral region of a strong earthquake. The maximum expected earthquake and the Safe Shut-Down Earthquake respectively, are fixed by the aid of a frequency map of strong earthquakes and a map of extreme earthquake intensities in Austria based on macroseismic data since 1201 A.D. The corresponding values of acceleration will be prescribed according to the state of science, but must at least be 0.10 g for the horizontal and 0.05 g for the vertical component of acceleration at the basement

The Diamond machine protection system

International Nuclear Information System (INIS)

Heron, M.T.; Lay, S.; Chernousko, Y.; Hamadyk, P.; Rotolo, N.

2012-01-01

The Diamond Light Source Machine Protection System (MPS) manages the hazards from high power photon beams and other hazards to ensure equipment protection on the booster synchrotron and storage ring. The system has a shutdown requirement, on a beam mis-steer of under 1 msec and has to manage in excess of a thousand interlocks. This is realised using a combination of bespoke hardware and programmable logic controllers. The MPS monitors a large number of interlock signals from diagnostics instrumentation, vacuum instrumentation, photon front ends and plant monitoring subsystems. Based on logic it can then remove the source of the energy to ensure protection of equipment. Depending on requirements, interlocks are managed on a Local or a Global basis. The Global system is structured as two layers, and supports fast- and slow-response-time interlock requirements. A Global MPS module takes the interlock permits for a given interlock circuit from each of the cells of the accelerator, and, subject to all interlocks being good, produces a permit to operate the source of energy: the RF amplifier for vessel protection and the PSU for magnet protection. The Local MPS module takes fast Interlock inputs from one cell of the Storage Ring or one quadrant of the Booster. Fast interlocks are those that must drop the beam in under 400 μsec (the maximum speed of the interlock) in the event of failure. EPIC provides the user interface to the MPS system

Trends in the structures development of the regional machine-building complex

Directory of Open Access Journals (Sweden)

Ershova I.V.

2017-01-01

Full Text Available In the process of market reforms of the Russian machine-building complex several distinct periods can be revealed. In this article the authors define periods of mass disintegration and spontaneous integration (since the beginning of the reforms until the financial crisis of 1996, post-crisis stabilization, directional specialization (2000-2008 and evolutionary development (since 2010. The economic consequences of the enterprises mergers and divisions are shown on the example of machine-building enterprises of the Middle Urals. The aim of this study is to substantiate the methodical approach to the selection of the optimal organizational structure for the machine-building business. The necessity of taking into account the extent of the personnel diversification and the production volume has been revealed for the optimum organizational structure determination in the machine-building associations. The authors have analyzed sales profitability of the 2745 machine-building enterprises, depending on the production scale and industry sector. The factors affecting the development of cooperative ties and outsourcing have been defined. The authors have made a conclusion that it is necessary to form technological chains as a new kind of business associations.

Applicability of LBB concept to tokamak-type fusion machine

International Nuclear Information System (INIS)

Nakahira, Masataka

2003-12-01

A tokamak-type fusion machine has been characterized as having inherent plasma shutdown safety. An extremely small leakage of impurities such as primary cooling water, i.e., less than 0.1 g/s, will cause a plasma disruption. This plasma disruption will induce electromagnetic forces (EM forces) acting in the Vacuum Vessel (VV) and plasma-facing components. The VV forms the physical barrier that encloses tritium and activated dust. If the VV has the possibility of sustaining an unstable fracture from a through crack caused by EM forces, the structural safety will be assured and the inherent safety will be demonstrated. This paper analytically assures the Leak-Before-Break (LBB) concept as applied to the VV and is based on experimental leak rate data of a through crack having a very small opening. Based on the analysis, the critical crack length to terminate plasma is evaluated as about 2 mm. On the other hand, the critical crack length for unstable fracture is obtained as about 400 mm. It is therefore concluded that EM forces induced by small leak to terminate plasma will not cause the unstable fracture of VV, and then the inherent safety is demonstrated. (author)

Quality control and performance evaluation of microselectron HDR machine over 30 months

International Nuclear Information System (INIS)

Balasubramanian, N.; Annex, E.H.; Sunderam, N.; Patel, N.P.; Kaushal, V.

2008-01-01

To assess the performance evaluation of Microselectron HDR machine the standard quality control and quality assurance checks were carried out after each loading of new 192 Ir brachytherapy source In the machine. Total 9 loadings were done over a period of 30 months

Technical Specification action statements requiring shutdown

International Nuclear Information System (INIS)

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

1993-11-01

When safety systems fail during power operation, the limiting conditions for operation (LCOs) and associated action statements of technical specifications typically require that the plant be shut down within the limits of allowed outage time (AOT). However, when a system needed to remove decay heat, such as the residual heat removal (RHR) system, is inoperable or degraded, shutting down the plant may not necessarily be preferable, from a risk perspective, to continuing power operation over a usual repair time, giving priority to the repairs. The risk impact of the basic operational alternatives, i.e., continued operation or shutdown, was evaluated for failures in the RHR and standby service water (SSW) systems of a boiling-water reactor (BWR) nuclear power plant. A complete or partial failure of the SSW system fails or degrades not only the RHR system but other front-line safety systems supported by the SSW system. This report presents the methodology to evaluate the risk impact of LCOs and associated AOT; the results of risk evaluation from its application to the RHR and SSW systems of a BWR; the findings from the risk-sensitivity analyses to identify alternative operational policies; and the major insights and recommendations to improve the technical specifications action statements

Lithium Hideout and Return in the CANDU Heat Transport System during Shutdown and Start-up

International Nuclear Information System (INIS)

Qiu, L.; Snaglewski, A.P.

2012-09-01

Lithium hydroxide is used to control the pH a (pH apparent) of the Heat Transport System (HTS) coolant in CANDU R reactors. The recommended range of the lithium concentration in the coolant is between 0.38 ppm (5.5x10 -5 m) and 0.60 ppm (8.7x10 -5 m) to minimize carbon steel corrosion in the HTS and magnetite deposition in the core during normal operation; this corresponds to pH a values between 10.2 and 10.4. Similar pH a and lithium concentrations should be maintained during shutdown and start-up. However, maintaining the pH a of the HTS coolant within specification during shutdown and start-up has been difficult for some CANDU stations, especially when the HTS is taken to a Low Level Drain State (LLDS), because of lithium hideout and return. This paper presents the results from lithium adsorption and desorption studies on iron oxides under relevant shutdown and start-up chemistry conditions performed to elucidate the mechanisms of the observed lithium hideout and return. The results show that lithium hideout and return are driven largely by changes in the solubility of magnetite as the HTS coolant chemistry changes during shutdown; changes in lithium concentration were inversely correlated with the solubility of magnetite. When the HTS system is de-pressurized and drained to a low coolant level, the ingress of air rapidly oxidizes the dissolved Fe (II) in the coolant, 2Fe +2 + 1 / 2 O 2 + 3 H 2 = 2FEOOH + 4 H + , resulting in the formation of lepidocrocite or maghemite, which have much lower solubilities but larger surface areas than does magnetite. The large surface area of the Fe (III) oxides can adsorb significant quantities of lithium from the coolant, leading to lithium hideout and a pH a decrease. During start-up, the chemistry of the coolant changes from oxidizing to reducing, and lepidocrocite and other Fe (III) oxides are reduced to Fe (II), gradually dissolving as their solubility increases with increasing temperature. The adsorbed lithium is released

Effect of Machining Velocity in Nanoscale Machining Operations

International Nuclear Information System (INIS)

Islam, Sumaiya; Khondoker, Noman; Ibrahim, Raafat

2015-01-01

The aim of this study is to investigate the generated forces and deformations of single crystal Cu with (100), (110) and (111) crystallographic orientations at nanoscale machining operation. A nanoindenter equipped with nanoscratching attachment was used for machining operations and in-situ observation of a nano scale groove. As a machining parameter, the machining velocity was varied to measure the normal and cutting forces. At a fixed machining velocity, different levels of normal and cutting forces were generated due to different crystallographic orientations of the specimens. Moreover, after machining operation percentage of elastic recovery was measured and it was found that both the elastic and plastic deformations were responsible for producing a nano scale groove within the range of machining velocities from 250-1000 nm/s. (paper)

Application of PSA to reduce frequency of unplanned shutdown of the reactor

International Nuclear Information System (INIS)

Tanipanichskul, P.

1988-08-01

The relative importance of all the operating and safety systems of the reactor TRR-1/M1 as well as the major failure modes of the systems are pointed out. The average unavailability of the reactor is 3·3 E-2 per cycle of operation which is in the range value of the actual reactor shutdown recorded during normal operation. Some guidance for annual maintenance and also suggestions for system development to increase safety systems reliability are determined. PSA was applied to improve the safety systems reliability of an operating research reactor. Refs, tabs

Modeling startup and shutdown transient of the microlinear piezo drive via ANSYS

Science.gov (United States)

Azin, A. V.; Bogdanov, E. P.; Rikkonen, S. V.; Ponomarev, S. V.; Khramtsov, A. M.

2017-02-01

The article describes the construction-design of the micro linear piezo drive intended for a peripheral cord tensioner in the reflecting surface shape regulator system for large-sized transformable spacecraft antenna reflectors. The research target -the development method of modeling startup and shutdown transient of the micro linear piezo drive. This method is based on application software package ANSYS. The method embraces a detailed description of the calculation stages to determine the operating characteristics of the designed piezo drive. Based on the numerical solutions, the time characteristics of the designed piezo drive are determined.

On the Conditioning of Machine-Learning-Assisted Turbulence Modeling

Science.gov (United States)

Wu, Jinlong; Sun, Rui; Wang, Qiqi; Xiao, Heng

2017-11-01

Recently, several researchers have demonstrated that machine learning techniques can be used to improve the RANS modeled Reynolds stress by training on available database of high fidelity simulations. However, obtaining improved mean velocity field remains an unsolved challenge, restricting the predictive capability of current machine-learning-assisted turbulence modeling approaches. In this work we define a condition number to evaluate the model conditioning of data-driven turbulence modeling approaches, and propose a stability-oriented machine learning framework to model Reynolds stress. Two canonical flows, the flow in a square duct and the flow over periodic hills, are investigated to demonstrate the predictive capability of the proposed framework. The satisfactory prediction performance of mean velocity field for both flows demonstrates the predictive capability of the proposed framework for machine-learning-assisted turbulence modeling. With showing the capability of improving the prediction of mean flow field, the proposed stability-oriented machine learning framework bridges the gap between the existing machine-learning-assisted turbulence modeling approaches and the demand of predictive capability of turbulence models in real applications.

Indonesian Stock Prediction using Support Vector Machine (SVM

Directory of Open Access Journals (Sweden)

Santoso Murtiyanto

2018-01-01

Full Text Available This project is part of developing software to provide predictive information technology-based services artificial intelligence (Machine Intelligence or Machine Learning that will be utilized in the money market community. The prediction method used in this early stages uses the combination of Gaussian Mixture Model and Support Vector Machine with Python programming. The system predicts the price of Astra International (stock code: ASII.JK stock data. The data used was taken during 17 yr period of January 2000 until September 2017. Some data was used for training/modeling (80 % of data and the remainder (20 % was used for testing. An integrated model comprising Gaussian Mixture Model and Support Vector Machine system has been tested to predict stock market of ASII.JK for l d in advance. This model has been compared with the Market Cummulative Return. From the results, it is depicts that the Gaussian Mixture Model-Support Vector Machine based stock predicted model, offers significant improvement over the compared models resulting sharpe ratio of 3.22.

Behaviour of alloys by abrasive erosion and carbide formation by welding; Comportamiento frente al desgaste abrasivo de las aleaciones con tendencias a la formacion de carburos aplicadas por soldadura

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-07-01

The abrasion of the mechanic elements for cut and extraction of minerals implies high cost because the replacement of the damaged elements and shutdown of the machines high cost because the replacement of the damaged elements and shutdown of the machines. The present article abstracts the results obtained in a project of investigation where the variables determining the quality of antiabrasive recharges have been obtained, and a method of evaluation of the different products of this type of recharges existing in the market have been evaluated. (Author) 9 refs.

Prediction of Machine Tool Condition Using Support Vector Machine

International Nuclear Information System (INIS)

Wang Peigong; Meng Qingfeng; Zhao Jian; Li Junjie; Wang Xiufeng

2011-01-01

Condition monitoring and predicting of CNC machine tools are investigated in this paper. Considering the CNC machine tools are often small numbers of samples, a condition predicting method for CNC machine tools based on support vector machines (SVMs) is proposed, then one-step and multi-step condition prediction models are constructed. The support vector machines prediction models are used to predict the trends of working condition of a certain type of CNC worm wheel and gear grinding machine by applying sequence data of vibration signal, which is collected during machine processing. And the relationship between different eigenvalue in CNC vibration signal and machining quality is discussed. The test result shows that the trend of vibration signal Peak-to-peak value in surface normal direction is most relevant to the trend of surface roughness value. In trends prediction of working condition, support vector machine has higher prediction accuracy both in the short term ('One-step') and long term (multi-step) prediction compared to autoregressive (AR) model and the RBF neural network. Experimental results show that it is feasible to apply support vector machine to CNC machine tool condition prediction.

Pricing and Availability Intervention in Vending Machines at Four Bus Garages

Science.gov (United States)

Hannan, Peter J; Harnack, Lisa J; Mitchell, Nathan R; Toomey, Traci L; Gerlach, Anne

2009-01-01

Objective To evaluate the effects of lowering prices and increasing availability on sales of healthy foods and beverages from 33 vending machines in four bus garages as part of a multi-component worksite obesity prevention intervention. Methods Availability of healthy items was increased to 50% and prices were lowered at least 10% in the vending machines in two metropolitan bus garages for an 18-month period. Two control garages offered vending choices at usual availability and prices. Sales data were collected monthly from each of the vending machines at the four garages. Results Increases in availability to 50% and price reductions of an average of 31% resulted in 10-42% higher sales of the healthy items. Employees were most price-responsive for snack purchases. Conclusions Greater availability and lower prices on targeted food and beverage items from vending machines was associated with greater purchases of these items over an eighteen-month period. Efforts to promote healthful food purchases in worksite settings should incorporate these two strategies. PMID:20061884

PSA-operations synergism for the advanced test reactor shutdown operations PSA

International Nuclear Information System (INIS)

Atkinson, S.A.

1996-01-01

The Advanced Test Reactor (ATR) Probabilistic Safety Assessment (PSA) for shutdown operations, cask handling, and canal draining is a successful example of the importance of good PSA-operations synergism for achieving a realistic and accepted assessment of the risks and for achieving desired risk reduction and safety improvement in a best and cost-effective manner. The implementation of the agreed-upon upgrades and improvements resulted in the reductions of the estimated mean frequency for core or canal irradiated fuel uncovery events, a total reduction in risk by a factor of nearly 1000 to a very low and acceptable risk level for potentially severe events

Environmentally Friendly Machining

CERN Document Server

Dixit, U S; Davim, J Paulo

2012-01-01

Environment-Friendly Machining provides an in-depth overview of environmentally-friendly machining processes, covering numerous different types of machining in order to identify which practice is the most environmentally sustainable. The book discusses three systems at length: machining with minimal cutting fluid, air-cooled machining and dry machining. Also covered is a way to conserve energy during machining processes, along with useful data and detailed descriptions for developing and utilizing the most efficient modern machining tools. Researchers and engineers looking for sustainable machining solutions will find Environment-Friendly Machining to be a useful volume.

Increased risk of a shutdown of ocean convection posed by warm North Atlantic summers

Science.gov (United States)

Oltmanns, Marilena; Karstensen, Johannes; Fischer, Jürgen

2018-04-01

A shutdown of ocean convection in the subpolar North Atlantic, triggered by enhanced melting over Greenland, is regarded as a potential transition point into a fundamentally different climate regime1-3. Noting that a key uncertainty for future convection resides in the relative importance of melting in summer and atmospheric forcing in winter, we investigate the extent to which summer conditions constrain convection with a comprehensive dataset, including hydrographic records that are over a decade in length from the convection regions. We find that warm and fresh summers, characterized by increased sea surface temperatures, freshwater concentrations and melting, are accompanied by reduced heat and buoyancy losses in winter, which entail a longer persistence of the freshwater near the surface and contribute to delaying convection. By shortening the time span for the convective freshwater export, the identified seasonal dynamics introduce a potentially critical threshold that is crossed when substantial amounts of freshwater from one summer are carried over into the next and accumulate. Warm and fresh summers in the Irminger Sea are followed by particularly short convection periods. We estimate that in the winter 2010-2011, after the warmest and freshest Irminger Sea summer on our record, 40% of the surface freshwater was retained.

What are the required maintenance and consolidation activities to run at design performance levels (injectors and LHC) until 2035?

CERN Document Server

Baird, S

2014-01-01

Assuming that Linac4 is connected to the PSB in LS2, we will outline the maintenance and basic consolidation works that will be needed to maintain design performance of the LHC and its Injector chain until 2035, with an overall reliability as good as that achieved in the first LHC operation period 2009 to 2013. Using these data we will estimate the shutdown schedule needed throughout this period to complete these maintenance and consolidation works. These estimates will also include the required radiation cool-down periods, time for system re-commissioning and testing as well as the time needed to restart the accelerator chain for LHC colliding beam operation. As some of the consolidation activities needed for the PS and SPS machines are related to the radia tion dose taken by the machine equipment (e.g., irradiated cable replacement and magnet renovation) the variation of these time estimates as a function of beam losses in the Injector chain will also be covered.

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

International Nuclear Information System (INIS)

Pierce, B.F.

1986-07-01

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

Inventory of radioactive corrosion products on the primary surfaces and release during shutdown in Ringhals 2

International Nuclear Information System (INIS)

Aronsson, O.

1994-01-01

In Ringhals 2 a retrospective study using gamma scans of system surfaces, fuel crud sampling and reactor coolant analyses during operation and shutdown has been done. The data have been used to prepare a balance of activity inventory. The inventory has been fairly stable from 1986 to 1993, expressed as a gamma source term. The steam generator replacement in 1989 removed some 40-50% of the Co-60 inventory in the reactor system. After the steam generator replacement, the gamma source term has got an increasing contribution from Co-58, absolutely as well as relatively. The reason for this is probably the switch from high pH operation to modified pH operation. Corrosion from fresh alloy 690 surfaces in the new steam generators is probably another contributing factor. The inventory and production rate of Co-60 is decreasing over the years. It has also been found that clean-up of the reactor coolant during start-up, operation, and shutdown as well as the fuel pool during refuelling removes about the same amounts of Co-60. (author). 11 figs., 15 refs

Design of a Three-Axis Machine Tool Module

National Research Council Canada - National Science Library

Childers, Marshal

2003-01-01

This report documents the design improvement process of the components in a tool module for a three-axis machine tool, which occurred during the period of March-April 2002 in support of a critical U.S...

Machine Replacement, Technology Adoption and Convergence.

OpenAIRE

Boucekkine, Raouf; Martinez, Blanca

1999-01-01

In this paper, we introduce adoption costs in a canonical vintage capital model. Adoption costs take the form of a direct loss in production during a fixed period of time. We explicitly characterize the optimal machine replacement policy as a function of the adoption period. Using an explicit numerical method, we study the dynamics of the model. In particular, we find that while an increase in the adoption costs lowers the long run level of output, it also rises the magnitude of short run flu...

Hybrid machining processes perspectives on machining and finishing

CERN Document Server

Gupta, Kapil; Laubscher, R F

2016-01-01

This book describes various hybrid machining and finishing processes. It gives a critical review of the past work based on them as well as the current trends and research directions. For each hybrid machining process presented, the authors list the method of material removal, machining system, process variables and applications. This book provides a deep understanding of the need, application and mechanism of hybrid machining processes.

Test rig overview for validation and reliability testing of shutdown system software

International Nuclear Information System (INIS)

Zhao, M.; McDonald, A.; Dick, P.

2007-01-01

The test rig for Validation and Reliability Testing of shutdown system software has been upgraded from the AECL Windows-based test rig previously used for CANDU6 stations. It includes a Virtual Trip Computer, which is a software simulation of the functional specification of the trip computer, and a real-time trip computer simulator in a separate chassis, which is used during the preparation of trip computer test cases before the actual trip computers are available. This allows preparation work for Validation and Reliability Testing to be performed in advance of delivery of actual trip computers to maintain a project schedule. (author)

Failure analysis for ultrasound machines in a radiology department after implementation of predictive maintenance method

Directory of Open Access Journals (Sweden)

Greg Chu

2018-01-01

Full Text Available Objective: The objective of the study was to perform quantitative failure and fault analysis to the diagnostic ultrasound (US scanners in a radiology department after the implementation of the predictive maintenance (PdM method; to study the reduction trend of machine failure; to understand machine operating parameters affecting the failure; to further optimize the method to maximize the machine clinically service time. Materials and Methods: The PdM method has been implemented to the 5 US machines since 2013. Log books were used to record machine failures and their root causes together with the time spent on repair, all of which were retrieved, categorized, and analyzed for the period between 2013 and 2016. Results: There were a total of 108 cases of failure occurred in these 5 US machines during the 4-year study period. The average number of failure per month for all these machines was 2.4. Failure analysis showed that there were 33 cases (30.5% due to software, 44 cases (40.7% due to hardware, and 31 cases (28.7% due to US probe. There was a statistically significant negative correlation between the time spent on regular quality assurance (QA by hospital physicists with the time spent on faulty parts replacement over the study period (P = 0.007. However, there was no statistically significant correlation between regular QA time and total yearly breakdown case (P = 0.12, although there has been a decreasing trend observed in the yearly total breakdown. Conclusion: There has been a significant improvement on the machine failure of US machines attributed to the concerted effort of sonographers and physicists in our department to practice the PdM method, in that system component repair time has been reduced, and a decreasing trend in the number of system breakdown has been observed.

Behavior of antimony isotopes in the primary coolant of WWER-1000-type nuclear reactors in NPP Kozloduy during operation and shutdown

International Nuclear Information System (INIS)

Dobrevski, Ivan D.; Zaharieva, Neli N.; Minkova, Katia F.; Gerchev, Nikolay B.

2009-01-01

This paper focuses on the behavior of the antimony isotopes 122 Sb and 124 Sb in the coolant of the WWER reactors in the nuclear power plant Kozloduy (Bulgaria) during operation and shutdown. It is concluded that the chemical properties of their actual precursor, the isotope 121 Sb, determine the behavior of 122 Sb and 124 Sb during operation, load fluctuations, and shutdown as well as during the reactor coolant purification process. It is supposed that differences between the reactor bulk and the core fuel cladding surface chemistry as well as the presence of sub-cooled nucleate boiling at the fuel cladding may create conditions under which a local oxidizing environment may come into existence. (orig.)

Internal fuel motion as an inherent shutdown mechanism for LMFBR accidents: PINEX-3, PINEX-2, and HUT 5-2A experiments

International Nuclear Information System (INIS)

Ferrell, P.C.; Porten, D.R.; Martin, F.J.

1981-01-01

The PINEX-2 experiment verified the concept of axial internal molten fuel motion within annular fuel, representing an inherent shutdown mechanism for hypothetical transient overpower excursions on the order of 5$/s. The PINEX-3 experiment, simulating a 50 cents/s transient overpower, showed that limitations on the effectiveness of fuel motion may arise from freezing of the fuel and blockage of the internal movement. Analysis of these experiments was performed to assess the physical processes that dominate fuel relocation potential and to apply them to prototypic LMFBR pin conditions. Results indicate that internal fuel motion should be reliable as a shutdown mechanism in LMFBR's for a range of reactivity insertion rates beyond presently available experimental data

CEBAF Control Room Renovation

International Nuclear Information System (INIS)

Michael Spata; Anthony Cuffe; Thomas Oren

2005-01-01

The Machine Control Center (MCC) at Jefferson Lab's Continuous Electron Beam Accelerator Facility (CEBAF) was constructed in the early 1990s and based on proven technology of that era. Through our experience over the last 15 years and in our planning for the facilities 12 GeV upgrade we reevaluated the control room environment to capitalize on emerging visualization and display technologies and improve on work-flow processes and ergonomic attributes. The renovation was performed in two phases during the summer of 2004, with one phase occurring during machine operations and the latter, more extensive phase, occurring during our semi-annual shutdown period. The new facility takes advantage of advances in display technology, analog and video signal management, server technology, ergonomic workspace design, lighting engineering, acoustic ceilings and raised flooring solutions to provide a marked improvement in the overall environment of machine operations

The use of neutron sources in nuclear reactors start-up after long shutdown periods

International Nuclear Information System (INIS)

Ponzoni Filho, P.; Borges, J.B.

1990-01-01

The reasons for the use of neutron sources in nuclear reactors, the different kinds of sources used and the alternatives to obtain the required minimum neutron counts in the external source range detectors after long maintenance and refueling periods are presented and discussed. The paper presents a formulation based in physics principles and experimental data, to calculate the power and time of reactor operation required to increase the effective fluence of secondary neutron sources. The option of using actinides produced during operation of the reactor as an additional source of neutrons is also discussed in depth to allow similar calculations in other kinds of reactors. The re-utilization of primary sources is considered as a last option. (author)

Design criteria for a self-actuated shutdown system to ensure limitation of core damage

International Nuclear Information System (INIS)

Deane, N.A.; Atcheson, D.B.

1981-09-01

Safety-based functional requirements and design criteria for a self-actuated shutdown system (SASS) are derived in accordance with LOA-2 success criteria and reliability goals. The design basis transients have been defined and evaluated for the CDS Phase II design, which is a 2550 MWt mixed oxide heterogeneous core reactor. A partial set of reactor responses for selected transients is provided as a function of SASS characteristics such as reactivity worth, trip points, and insertion times

Replacement energy, capacity, and reliability costs for permanent nuclear reactor shutdowns

International Nuclear Information System (INIS)

VanKuiken, J.C., Buehring, W.A.; Hamilton, S.; Kavicky, J.A.; Cavallo, J.D.; Veselka, T.D.; Willing, D.L.

1993-10-01

Average replacement power costs are estimated for potential permanent shutdowns of nuclear electricity-generating units. Replacement power costs are considered to include replacement energy, capacity, and reliability cost components. These estimates were developed to assist the US Nuclear Regulatory Commission in evaluating regulatory issues that potentially affect changes in serious reactor accident frequencies. Cost estimates were derived from long-term production-cost and capacity expansion simulations of pooled utility-system operations. Factors that affect replacement power cost, such as load growth, replacement sources of generation, and capital costs for replacement capacity, were treated in the analysis. Costs are presented for a representative reactor and for selected subcategories of reactors, based on estimates for 112 individual reactors

Chuck for machining armature casings and angles

International Nuclear Information System (INIS)

Tashlitskii, A.I.; Matskevich, A.I.

1984-01-01

When machining T-joints and angles, the test specimen must be fixed before being placed in the desired position. This is quite a complex operation and is achieved in a few stages. At the Scientific Production Combine ''Kislorodmash,'' a new chuck was designed which in one pressing of the jaws seats and fixes the specimen. In the clamped condition, the chuck helps rotate and fix the specimen in one of the four positions. Rotating and fixing are manual. The chuck developed ensured a distinct interdependence of the axes of the branches being machined as the specimen remains fixed throughout the period of machining, and provides reliable fixing of the specimen, and there are no clearances when the specimen is fixed with a special wedge. When using the chuck, the ancillary movements of the operator are reduced to a minimum thus increasing the labor productivity

The design and improvement of radial tire molding machine

Science.gov (United States)

Wang, Wenhao; Zhang, Tao

2018-04-01

This paper presented that the high accuracy semisteel meridian tire molding machine structure configurations, combining tyre high precision characteristics, the original structure and parameter optimization, technology improvement innovation design period of opening and closing machine rotary shaping drum institutions. This way out of the shaft from the structure to the push-pull type movable shaping drum of thinking limit, compared with the specifications and shaping drum can smaller contraction, is conducive to forming the tire and reduce the tire deformation.

Event sequence quantification for a loss of shutdown cooling accident in the GCFR

International Nuclear Information System (INIS)

Frank, M.; Reilly, J.

1979-10-01

A summary is presented of the core-wide sequence of events of a postulated total loss of forced and natural convection decay heat removal in a shutdown Gas-Cooled Fast Reactor (GCFR). It outlines the analytical methods and results for the progression of the accident sequence. This hypothetical accident proceeds in the distinct phases of cladding melting, assembly wall melting and molten steel relocation into the interassembly spacing, and fuel relocation. It identifies the key phenomena of the event sequence and the concerns and mechanisms of both recriticality and recriticality prevention

Verification and validation of the R2Smesh approach for the calculation of high resolution shutdown dose rate distributions

Czech Academy of Sciences Publication Activity Database

Majerle, Mitja; Leichtle, D.; Fischer, U.; Serikov, A.

2012-01-01

Roč. 87, 5-6 (2012), s. 443-447 ISSN 0920-3796 Institutional support: RVO:61389005 Keywords : MCNP * FISPACT * shutdown dose rate Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders OBOR OECD: Nuclear physics Impact factor: 0.842, year: 2012

Machine terms dictionary

Energy Technology Data Exchange (ETDEWEB)

NONE

1979-04-15

This book gives descriptions of machine terms which includes machine design, drawing, the method of machine, machine tools, machine materials, automobile, measuring and controlling, electricity, basic of electron, information technology, quality assurance, Auto CAD and FA terms and important formula of mechanical engineering.

Modelling the fluid structure interaction produced by a waterhammer during shutdown of high-pressure pumps

International Nuclear Information System (INIS)

Erath, W.; Nowotny, B.; Maetz, J.

1999-01-01

Measurements of an experiment in a pipe system with pump shutdown and valve closing have been performed in the nuclear power plant KRB II (Gundremmingen, Germany). Comparative calculations of fluid and structure including interaction show an excellent agreement with the measured results. Theory and implementation of the fluid structure interaction (FSI) and the results of the comparison are described. The following measurements have been compared with calculations: (1) experiments in Delft, Netherlands to analyse the FSI; and (2) experiment with pump shutdown and valve closing in the nuclear power plant KRB II has been performed. It turns out, that the consideration of the FSI is necessary for an exact calculation of 'soft' piping systems. It has significant application in current waterhammer problems. For example, water column closure, vapour collapse, check valve slamming continues to create waterhammers in the energy industry. An important consequence of the FSI is mostly a significant increase of the effective structural damping. This mitigates - so far in all KED's calculations the FSI has taken into account - an amplification of pipe movements due to pressure waves in resonance with structural eigenvalues. To investigate the integrity of pipe systems pipe stresses are calculated. Taking FSI into account they are reduced by 10-40% in the actual case. (orig.)

Development of Risk Assessment Technology for Low Power, Shutdown and Digital I and C System

International Nuclear Information System (INIS)

Jang, Seung Cheol; Kang, Hyun Gook; Lim, Ho Gon; Park, Jin Hee; Kang, Dae Il; Eom, Heung Sub; Kim, Man Cheol; Lee, Ho Joong; Kim, Jae Whan; Ha, Jae Joo

2007-06-01

There are two technical areas to deal with in the project: the low power and shutdown probabilistic safety assessment (PSA), and the digital I and C PSA. The scope and contents of each area could be summarized as follows: The LPSD PSA Area Ο Quality improvement of the KSNP LPSD PSA model in the following four technical areas; human reliability analysis (HR), system analysis (SY), data analysis (DA) and accident sequence quantification (QU) Ο Development of the LPSD configuration risk management(CRM) model - Study on the methodology for developing a CRM model, so-called ASLOC (Autonomous Shutdown LOgic Creation) - Development of the LPSD CRM model for the units of Ulchin 3 and 4 The Digital I and C PSA Area Ο Development of impact model of ESF-CCS on plant risks - Unavailability analysis of ESF-CCS for APR-1400 - Digital plant risk models for evaluating core damage frequency (CDF) Ο Study on the methodologies for treating digital-specific problems in the digital I and C PSA - Study on the methodology for evaluating safety-critical SW reliability by BBN techniques, including a feasibility study of reliability growth model - Study on the methodology for the safety-critical network system by Markov chain

Understanding the hydrologic impacts of wastewater treatment plant discharge to shallow groundwater: Before and after plant shutdown

Science.gov (United States)

Hubbard, Laura E.; Keefe, Steffanie H.; Kolpin, Dana W.; Barber, Larry B.; Duris, Joseph W.; Hutchinson, Kasey J.; Bradley, Paul M.

2016-01-01

Effluent-impacted surface water has the potential to transport not only water, but wastewater-derived contaminants to shallow groundwater systems. To better understand the effects of effluent discharge on in-stream and near-stream hydrologic conditions in wastewater-impacted systems, water-level changes were monitored in hyporheic-zone and shallow-groundwater piezometers in a reach of Fourmile Creek adjacent to and downstream of the Ankeny (Iowa, USA) wastewater treatment plant (WWTP). Water-level changes were monitored from approximately 1.5 months before to 0.5 months after WWTP closure. Diurnal patterns in WWTP discharge were closely mirrored in stream and shallow-groundwater levels immediately upstream and up to 3 km downstream of the outfall, indicating that such discharge was the primary control on water levels before shutdown. The hydrologic response to WWTP shutdown was immediately observed throughout the study reach, verifying the far-reaching hydraulic connectivity and associated contaminant transport risk. The movement of WWTP effluent into alluvial aquifers has implications for potential WWTP-derived contamination of shallow groundwater far removed from the WWTP outfall.

Level 1 probabilistic risk assessment of low power and shutdown operations at a PWR: Phase 2 results

International Nuclear Information System (INIS)

Chu, T.L.; Bozoki, G.; Kohut, P.; Musicki, Z.; Wong, S.M.; Yang, J.; Hsu, C.J.; Diamond, D.J.; Su, R.F.; Holmes, B.; Siu, N.; Bley, D.; Lin, J.

1992-01-01

As a result of the Chernobyl accident and other precursor events (e.g., Diablo Canyon), the US Nuclear Regulatory Commission's (NRC's) Office of Nuclear Regulatory Research (RES) initiated an extensive project during 1989 to carefully examine the potential risks during Low Power and Shutdown (LP ampersand S) operations. Shortly after the program began, an event occurred at the Vogtle plant during shutdown, which further intensified the effort of the LP ampersand S program. In the LP ampersand S program, one pressurized water reactor (PWR), Surry, and one boiling water reactor (BWR), Grand Gulf, were selected, mainly because they were previously analyzed in the NUREG-1150 Study. The Level-1 Program is being performed in two phases. Phase 1 was dedicated to performing a coarse screening level-1 analysis including internal fire and flood. A draft report was completed in November, 1991. In the phase 2 study, mid-loop operations at the Surry plant were analyzed in detail. The objective of this paper is to present the approach of the phase 2 study and the preliminary results and insights

Shielding optimisation of the ITER ICH&CD antenna for shutdown dose rate

International Nuclear Information System (INIS)

Turner, Andrew; Leichtle, Dieter; Lamalle, Philippe; Levesy, Bruno; Meunier, Lionel; Polunovskiy, Eduard; Sartori, Roberta; Shannon, Mark

2015-01-01

Highlights: • Neutronics analysis on the ITER ICH&CD system conducted to reduce shutdown dose rate. • Several designs for shielding the port plug gaps were modelled. • Shielding significantly reduced interspace dose rate but still exceed project requirements. • Design optimisation of the ICH port is continuing. • Significant contributions from other ports require an integrated modelling approach. - Abstract: The Ion Cyclotron Heating and Current Drive (ICH&CD) system will reside in ITER equatorial port plugs 13 and 15. Shutdown dose rates (SDDR) within the port interspace are required to be less than 100 μSv/h at 10 6 s cooling. A significant contribution to the SDDR results from neutrons streaming down gaps around the port frame, and the mitigation of this streaming is the main subject of these analyses. An updated MCNP model of the antenna was created and integrated into an ITER reference model. Shielding plates were defined in the port gaps, and scoping studies conducted to assess their effectiveness in several configurations, based on which a front dog-leg arrangement was selected for high resolution 3-D activation analysis using MCR2S. It was concluded that the selected configuration reduced the SDDR from ∼500 μSv/h to 220 μSv/h but were still in excess of dose rate requirements. Approximately 30% of this was due to cross-talk from neighbouring ports. In addition, increased dose rates were observed in the port interspace along the lines of sight of the removable vacuum transmission lines. Design optimisation is continuing, however an integrated approach is needed with regard to ITER port plug design and the shielding of surrounding systems.

Shielding optimisation of the ITER ICH&CD antenna for shutdown dose rate

Energy Technology Data Exchange (ETDEWEB)

Turner, Andrew, E-mail: andrew.turner@ccfe.ac.uk [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Leichtle, Dieter [Fusion for Energy, Josep Pla 2, Torres Diagonal Litoral B3, 08019 Barcelona (Spain); Lamalle, Philippe; Levesy, Bruno [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St., Paul-lez-Durance (France); Meunier, Lionel [Fusion for Energy, Josep Pla 2, Torres Diagonal Litoral B3, 08019 Barcelona (Spain); Polunovskiy, Eduard [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St., Paul-lez-Durance (France); Sartori, Roberta [Fusion for Energy, Josep Pla 2, Torres Diagonal Litoral B3, 08019 Barcelona (Spain); Shannon, Mark [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom)

2015-10-15

Highlights: • Neutronics analysis on the ITER ICH&CD system conducted to reduce shutdown dose rate. • Several designs for shielding the port plug gaps were modelled. • Shielding significantly reduced interspace dose rate but still exceed project requirements. • Design optimisation of the ICH port is continuing. • Significant contributions from other ports require an integrated modelling approach. - Abstract: The Ion Cyclotron Heating and Current Drive (ICH&CD) system will reside in ITER equatorial port plugs 13 and 15. Shutdown dose rates (SDDR) within the port interspace are required to be less than 100 μSv/h at 10{sup 6} s cooling. A significant contribution to the SDDR results from neutrons streaming down gaps around the port frame, and the mitigation of this streaming is the main subject of these analyses. An updated MCNP model of the antenna was created and integrated into an ITER reference model. Shielding plates were defined in the port gaps, and scoping studies conducted to assess their effectiveness in several configurations, based on which a front dog-leg arrangement was selected for high resolution 3-D activation analysis using MCR2S. It was concluded that the selected configuration reduced the SDDR from ∼500 μSv/h to 220 μSv/h but were still in excess of dose rate requirements. Approximately 30% of this was due to cross-talk from neighbouring ports. In addition, increased dose rates were observed in the port interspace along the lines of sight of the removable vacuum transmission lines. Design optimisation is continuing, however an integrated approach is needed with regard to ITER port plug design and the shielding of surrounding systems.

Risk contribution from low power and shutdown of a pressurized water reactor

International Nuclear Information System (INIS)

Chu, T.L.; Pratt, W.T.

1997-01-01

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 operation 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 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 non power 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 mid loop operation were chosen for analysis. Level 1 and Level 2/3 results from the Surry analyses are presented

Evaluation of Pressure Changes in HANARO Reactor Hall after a Reactor Shutdown

International Nuclear Information System (INIS)

Han, Geeyang; Han, Jaesam; Ahn, Gukhoon; Jung, Hoansung

2013-01-01

The major objective of this work is intended to evaluate the characteristics of the thermal behavior regarding how the decay heat will be affected by the reactor hall pressure change and the increase of pool water temperature induced in the primary coolant after a reactor shutdown. The particular reactor pool water temperature at the surface where it is evaporated owing to the decay heat resulting in the local heat transfer rate is related to the pressure change response in the reactor hall associated with the primary cooling system because of the reduction of the heat exchanger to remove the heat. The increase in the pool water temperature is proportional to the heat transfer rate in the reactor pool. Consequently, any limit on the reactor pool water temperature imposes a corresponding limit on the reactor hall pressure. At HANARO, the decay heat after a reactor shutdown is mainly removed by the natural circulation cooling in the reactor pool. This paper is written for the safety feature of the pressure change related leakage rate from the reactor hall. The calculation results show that the increase of pressure in the reactor hall will not cause any serious problems to the safety limits although the reactor hall pressure is slightly increased. Therefore, it was concluded that the pool water temperature increase is not so rapid as to cause the pressure to vary significantly in the reactor hall. Furthermore, the mathematical model developed in this work can be a useful analytical tool for scoping and parametric studies in the area of thermal transient analysis, with its proper representation of the interaction between the temperature and pressure in the reactor hall

Numerical simulator of the CANDU fueling machine driving desk

International Nuclear Information System (INIS)

Doca, Cezar

2008-01-01

As a national and European premiere, in the 2003 - 2005 period, at the Institute for Nuclear Research Pitesti two CANDU fueling machine heads, no.4 and no.5, for the Nuclear Power Plant Cernavoda - Unit 2 were successfully tested. To perform the tests of these machines, a special CANDU fueling machine testing rig was built and was (and is) available for this goal. The design of the CANDU fueling machine test rig from the Institute for Nuclear Research Pitesti is a replica of the similar equipment operating in CANDU 6 type nuclear power plants. High technical level of the CANDU fueling machine tests required the using of an efficient data acquisition and processing Computer Control System. The challenging goal was to build a computer system (hardware and software) designed and engineered to control the test and calibration process of these fuel handling machines. The design takes care both of the functionality required to correctly control the CANDU fueling machine and of the additional functionality required to assist the testing process. Both the fueling machine testing rig and staff had successfully assessed by the AECL representatives during two missions. At same the time, at the Institute for Nuclear Research Pitesti was/is developed a numerical simulator for the CANDU fueling machine operators training. The paper presents the numerical simulator - a special PC program (software) which simulates the graphics and the functions and the operations at the main desk of the computer control system. The simulator permits 'to drive' a CANDU fueling machine in two manners: manual or automatic. The numerical simulator is dedicated to the training of operators who operate the CANDU fueling machine in a nuclear power plant with CANDU reactor. (author)

Some relations between quantum Turing machines and Turing machines

OpenAIRE

Sicard, Andrés; Vélez, Mario

1999-01-01

For quantum Turing machines we present three elements: Its components, its time evolution operator and its local transition function. The components are related with the components of deterministic Turing machines, the time evolution operator is related with the evolution of reversible Turing machines and the local transition function is related with the transition function of probabilistic and reversible Turing machines.

Machine availability at the Large Hardron Collider

CERN Document Server

Pojer, M; Wagner, S

2012-01-01

One of the most important parameters for a particle accelerator is its uptime, the period of time when it is functioning and available for use. In its second year of operation, the Large Hadron Collider (LHC) has experienced high machine availability, which is one of the ingredients of its brilliant performance. Some of the reasons for the observed MTBF are presented. The approach of periodic maintenance stops is also discussed. Some considerations on the ideal length of a physics fill are drawn.

Machine availability at the Large Hardron Collider

OpenAIRE

Pojer, M; Schmidt, R; Wagner, S

2012-01-01

One of the most important parameters for a particle accelerator is its uptime, the period of time when it is functioning and available for use. In its second year of operation, the Large Hadron Collider (LHC) has experienced high machine availability, which is one of the ingredients of its brilliant performance. Some of the reasons for the observed MTBF are presented. The approach of periodic maintenance stops is also discussed. Some considerations on the ideal length of a physics fill are dr...

Support vector machine in machine condition monitoring and fault diagnosis

Science.gov (United States)

Widodo, Achmad; Yang, Bo-Suk

2007-08-01

Recently, the issue of machine condition monitoring and fault diagnosis as a part of maintenance system became global due to the potential advantages to be gained from reduced maintenance costs, improved productivity and increased machine availability. This paper presents a survey of machine condition monitoring and fault diagnosis using support vector machine (SVM). It attempts to summarize and review the recent research and developments of SVM in machine condition monitoring and diagnosis. Numerous methods have been developed based on intelligent systems such as artificial neural network, fuzzy expert system, condition-based reasoning, random forest, etc. However, the use of SVM for machine condition monitoring and fault diagnosis is still rare. SVM has excellent performance in generalization so it can produce high accuracy in classification for machine condition monitoring and diagnosis. Until 2006, the use of SVM in machine condition monitoring and fault diagnosis is tending to develop towards expertise orientation and problem-oriented domain. Finally, the ability to continually change and obtain a novel idea for machine condition monitoring and fault diagnosis using SVM will be future works.

An efficient flow-based botnet detection using supervised machine learning

DEFF Research Database (Denmark)

Stevanovic, Matija; Pedersen, Jens Myrup

2014-01-01

Botnet detection represents one of the most crucial prerequisites of successful botnet neutralization. This paper explores how accurate and timely detection can be achieved by using supervised machine learning as the tool of inferring about malicious botnet traffic. In order to do so, the paper...... introduces a novel flow-based detection system that relies on supervised machine learning for identifying botnet network traffic. For use in the system we consider eight highly regarded machine learning algorithms, indicating the best performing one. Furthermore, the paper evaluates how much traffic needs...... to accurately and timely detect botnet traffic using purely flow-based traffic analysis and supervised machine learning. Additionally, the results show that in order to achieve accurate detection traffic flows need to be monitored for only a limited time period and number of packets per flow. This indicates...

System design for the new TMX machine

International Nuclear Information System (INIS)

Chargin, A.K.; Calderon, M.O.; Mooney, L.J.; Vogtlin, G.E.

1977-01-01

The Tandem Mirror Experiment (TMX) is designed to test the physics of a new approach to Q-enhancement in open confinement systems. In the tandem mirror concept, the ends of a long solenoid are plugged electrostatically by means of ambipolar potential barriers created in two mirror machines or plugs, one at each end of the solenoid. The ambipolar potential in mirror machines develops as a consequence of the higher scattering rate of electrons and the balancing of electron and ion loss rates. The TMX experiment incorporates very few new engineering developments, but it does involve a new way of combining in an integrated system many previously developed ideas. The engineering task is to design the machine that would provide a proof-of-principle evaluation of the tandem mirror concept as rapidly as possible. The preliminary design was started in September 1976 and was completed by December 1976. It led to a cost estimate of $11 million and a scheduled construction period of 18 months

Optimal Overhaul-Replacement Policies for Repairable Machine Sold with Warranty

Directory of Open Access Journals (Sweden)

Kusmaningrum Soemadi

2014-12-01

Full Text Available This research deals with an overhaul-replacement policy for a repairable machine sold with Free Replacement Warranty (FRW. The machine will be used for a finite horizon, T (T <, and evaluated at a fixed interval, s (s< T. At each evaluation point, the buyer considers three alternative decisions i.e. Keep the machine, Overhaul it, or Replace it with a new identical one. An overhaul can reduce the machine age virtually, but not to a point that the machine is as good as new. If the machine fails during the warranty period, it is rectified at no cost to the buyer. Any failure occurring before and after the expiry of the warranty is restored by minimal repair. An overhaul-replacement policy is formulated for such machines by using dynamic programming approach to obtain the buyer’s optimal policy. The results show that a significant rejuvenation effect due to overhaul may extend the length of machine life cycle and delay the replacement decision. In contrast, the warranty stimulates early machine replacement and by then increases the replacement frequencies for a certain range of replacement cost. This demonstrates that to minimize the total ownership cost over T the buyer needs to consider the minimal repair cost reduction due to rejuvenation effect of overhaul as well as the warranty benefit due to replacement. Numerical examples are presented for both illustrating the optimal policy and describing the behavior of the optimal solution.

Sales of healthy snacks and beverages following the implementation of healthy vending standards in City of Philadelphia vending machines.

Science.gov (United States)

Pharis, Meagan L; Colby, Lisa; Wagner, Amanda; Mallya, Giridhar

2018-02-01

We examined outcomes following the implementation of employer-wide vending standards, designed to increase healthy snack and beverage options, on the proportion of healthy v. less healthy sales, sales volume and revenue for snack and beverage vending machines. A single-arm evaluation of a policy utilizing monthly sales volume and revenue data provided by the contracted vendor during baseline, machine conversion and post-conversion time periods. Study time periods are full calendar years unless otherwise noted. Property owned or leased by the City of Philadelphia, USA. Approximately 250 vending machines over a 4-year period (2010-2013). At post-conversion, the proportion of sales attributable to healthy items was 40 % for snacks and 46 % for beverages. Healthy snack sales were 323 % higher (38·4 to 162·5 items sold per machine per month) and total snack sales were 17 % lower (486·8 to 402·1 items sold per machine per month). Healthy beverage sales were 33 % higher (68·2 to 90·6 items sold per machine per month) and there was no significant change in total beverage sales (213·2 to 209·6 items sold per machine per month). Revenue was 11 % lower for snacks ($US 468·30 to $US 415·70 per machine per month) and 21 % lower for beverages ($US 344·00 to $US 270·70 per machine per month). Sales of healthy vending items were significantly higher following the implementation of employer-wide vending standards for snack and beverage vending machines. Entities receiving revenue-based commission payments from vending machines should employ strategies to minimize potential revenue losses.

Requirements Analysis Study for Master Pump Shutdown System Project Development Specification

International Nuclear Information System (INIS)

BEVINS, R.R.

2000-01-01

This study is a requirements document that presents analysis for the functional description for the master pump shutdown system. This document identifies the sources of the requirements and/or how these were derived. Each requirement is validated either by quoting the source or an analysis process involving the required functionality, performance characteristics, operations input or engineering judgment. The requirements in this study apply to the first phase of the W314 Project. This document has been updated during the definitive design portion of the first phase of the W314 Project to capture additional software requirements and is planned to be updated during the second phase of the W314 Project to cover the second phase of the project's scope

Simulations of Quantum Turing Machines by Quantum Multi-Stack Machines

OpenAIRE

Qiu, Daowen

2005-01-01

As was well known, in classical computation, Turing machines, circuits, multi-stack machines, and multi-counter machines are equivalent, that is, they can simulate each other in polynomial time. In quantum computation, Yao [11] first proved that for any quantum Turing machines $M$, there exists quantum Boolean circuit $(n,t)$-simulating $M$, where $n$ denotes the length of input strings, and $t$ is the number of move steps before machine stopping. However, the simulations of quantum Turing ma...

Delay dynamical systems and applications to nonlinear machine-tool chatter

International Nuclear Information System (INIS)

Fofana, M.S.

2003-01-01

The stability behaviour of machine chatter that exhibits Hopf and degenerate bifurcations has been examined without the assumption of small delays between successive cuts. Delay dynamical system theory leading to the reduction of the infinite-dimensional character of the governing delay differential equations (DDEs) to a finite-dimensional set of ordinary differential equations have been employed. The essential mathematical arguments for these systems in the context of retarded DDEs are summarized. Then the application of these arguments in the stability study of machine-tool chatter with multiple time delays is presented. Explicit analytical expressions ensuring stable and unstable machining when perturbations are periodic, stochastic and nonlinear have been derived using the integral averaging method and Lyapunov exponents

LAMPF first-fault identifier for fast transient faults

International Nuclear Information System (INIS)

Swanson, A.R.; Hill, R.E.

1979-01-01

The LAMPF accelerator is presently producing 800-MeV proton beams at 0.5 mA average current. Machine protection for such a high-intensity accelerator requires a fast shutdown mechanism, which can turn off the beam within a few microseconds of the occurrence of a machine fault. The resulting beam unloading transients cause the rf systems to exceed control loop tolerances and consequently generate multiple fault indications for identification by the control computer. The problem is to isolate the primary fault or cause of beam shutdown while disregarding as many as 50 secondary fault indications that occur as a result of beam shutdown. The LAMPF First-Fault Identifier (FFI) for fast transient faults is operational and has proven capable of first-fault identification. The FFI design utilized features of the Fast Protection System that were previously implemented for beam chopping and rf power conservation. No software changes were required

Gear failure of a PHWR refuelling machine

International Nuclear Information System (INIS)

Iorio, A.F.; Crespi, J.C.

1986-01-01

After ten year service in Atucha Nuclear Station a gear belonging to a pressurized heavy water reactor refuelling machine, failed. The gear box was used to transmit motion to the inlet-outlet heavy-water valve of that machine. Visual examination of the gear device revealed an absence of lubricant and several gear teeth were broken off at the root. The gear motion was transmitted from a speed-reducing device with controlled adjustable times in order to produce a right fitness of the valve closure. The main cause of gear failure was due to misalignment produced during assembly or in-service operation. It is suggested to control periodically the level of oil lubricant. (orig./IHOE) [de

Machine tool structures

CERN Document Server

Koenigsberger, F

1970-01-01

Machine Tool Structures, Volume 1 deals with fundamental theories and calculation methods for machine tool structures. Experimental investigations into stiffness are discussed, along with the application of the results to the design of machine tool structures. Topics covered range from static and dynamic stiffness to chatter in metal cutting, stability in machine tools, and deformations of machine tool structures. This volume is divided into three sections and opens with a discussion on stiffness specifications and the effect of stiffness on the behavior of the machine under forced vibration c

Implementation of Total Productive Maintenance (TPM to Improve Sheeter Machine Performance

Directory of Open Access Journals (Sweden)

Candra Nofri Eka

2017-01-01

Full Text Available This paper purpose is an evaluation of TPM implementation, as a case study at sheeter machine cut size line 5 finishing department, PT RAPP, Indonesia. Research methodology collected the Overall Equipment Effectiveness (OEE data of sheeter machine and computed its scores. Then, OEE analysis big losses, statistical analysis using SPSS 20 and focused maintenance evaluation of TPM were performed. The data collected to machine sheeter’s production for 10 months (January-October 2016. The data analyses was resulted the OEE average score of 82.75%. This score was still below the world class OEE (85% and the company target (90%. Based the big losses of OEE analysis was obtained the reduce speed losses, which most significant losses of OEE scores. The reduce speed losses value was 44.79% of total losses during the research period. The high score of these losses due to decreasing of machine production speed by operators, which intended to improve the quality of resulting products. The OEE scores statistical analysis was found breakdown losses and reduces speed losses, which significantly affected to OEE scores. Implementations of focused maintenance of TPM in the case study may need to improve because there were still occurred un-expecting losses during the research period.

Materiality of a simulation: Scratch reading machine, 1931

Directory of Open Access Journals (Sweden)

Craig Saper

2009-12-01

Full Text Available Using Bob Brown's reading machine and the prepared texts for his machine, called readies, both designed in 1930, as an example of scratch turntablist techniques, suggests an alternative to narrow definitions of literacy and new ways to appreciate the history of scratch techniques. Brown's machine resembles the turntablist’s ability to rapidly shift reading (its direction, speed, and repetition rather than slowly flipping the pages of a book. Punctuation marks, in the readies, become visual analogies. For movement we see em-dashes (— that also, by definition, indicate that the sentence was interrupted or cut short. The old uses of punctuation, such as employment of periods to mark the end of a sentence, disappear. The result looks like a script for a turntablist’s performance, and dj Herc starts to sound like a reading teacher. An online simulation of Brown's machine, http://www.readies.org, reproduce, or approximate, the motion, scratch, jerking, flickering, and visual effects produced or illuminated with the machine. Those supplemental aspects of reading are always already part of reading. The supplement (movement, visuality, mechanicity to traditional notions of literacy usually remain part of an implicate process. The reading machine and scratch techniques are not simply a new conduit for the same supposedly natural process. The scratch reading highlights what Jacques Derrida calls the "virtual multimedia" (of reading print on paper. The increasing prevalence, even omnipresent and [to some critics] epidemic, use of text(ing machines, something outside or beside traditional literacy, the scratch-meaning becomes foregrounded. Brown's machine puts the natural process of reading under erasure or scratch (simply by adjusting the speed, direction, and layout. dj Herc did the same for music.

Electricity of machine tool

International Nuclear Information System (INIS)

Gijeon media editorial department

1977-10-01

This book is divided into three parts. The first part deals with electricity machine, which can taints from generator to motor, motor a power source of machine tool, electricity machine for machine tool such as switch in main circuit, automatic machine, a knife switch and pushing button, snap switch, protection device, timer, solenoid, and rectifier. The second part handles wiring diagram. This concludes basic electricity circuit of machine tool, electricity wiring diagram in your machine like milling machine, planer and grinding machine. The third part introduces fault diagnosis of machine, which gives the practical solution according to fault diagnosis and the diagnostic method with voltage and resistance measurement by tester.

Review of occupational radiation exposures in all biennial shutdown maintenance of Kaiga generating station

International Nuclear Information System (INIS)

Murukan, E.K.; Vinod Kumar, T.; Austine, N.X.; Soumia Menon, M.; Girish Kumar, K.; Rao, M.M.L.N.; Venkataramana, K.

2008-01-01

Full text: Kaiga generating station 1 and 2 consists of twin units of 220 M We pressurized heavy water reactors located in Karnataka, India. Major maintenance activities of one of the twin units are taken up once in two years (biennial shutdown) to execute system maintenance, system up gradation, surveillance and in-service inspection (ISI) jobs. BSDs are mandatory activities to comply with regulatory requirement to ensure the safety and reliability of plant system equipment. More than 65% of the station collective dose is contributed by biennial shutdown (BSD) jobs. It is observed that the man rem consumed during normal operation of the plant is less than 35% of the total man rem consumed. Since BSD jobs contributes significantly to station collective dose, an effective implementation of radiation protection programme specific to BSD is the key to control the occupational exposure. Various improvements in the field of radiation protection practices and process systems are adopted to achieve lowest collective dose at par with international standards. The key areas identified for application of various strategies to achieve ALARA were Man rem budgeting, Radiological condition monitoring, Radiation protection practices, Identification of critical jobs and Work groups, Work planning and execution, and Radioactive waste management. Review of collective doses of all the BSD jobs performed in the station since year 2004 and various measures incorporated to achieve ALARA exposures to plant personnel are briefly discussed in this paper. (author)

Machine medical ethics

CERN Document Server

Pontier, Matthijs

2015-01-01

The essays in this book, written by researchers from both humanities and sciences, describe various theoretical and experimental approaches to adding medical ethics to a machine in medical settings. Medical machines are in close proximity with human beings, and getting closer: with patients who are in vulnerable states of health, who have disabilities of various kinds, with the very young or very old, and with medical professionals. In such contexts, machines are undertaking important medical tasks that require emotional sensitivity, knowledge of medical codes, human dignity, and privacy. As machine technology advances, ethical concerns become more urgent: should medical machines be programmed to follow a code of medical ethics? What theory or theories should constrain medical machine conduct? What design features are required? Should machines share responsibility with humans for the ethical consequences of medical actions? How ought clinical relationships involving machines to be modeled? Is a capacity for e...

Large Hadron Collider The Discovery Machine

CERN Multimedia

2008-01-01

The mammoth machine, after a nine-year construction period, is scheduled (touch wood) to begin producing its beams of particles later this year. The commissioning process is planned to proceed from one beam to two beams to colliding beams; from lower energies to the terascale; from weaker test intensities to stronger ones suitable for producing data at useful rates but more difficult to control.

Humanizing machines: Anthropomorphization of slot machines increases gambling.

Science.gov (United States)

Riva, Paolo; Sacchi, Simona; Brambilla, Marco

2015-12-01

Do people gamble more on slot machines if they think that they are playing against humanlike minds rather than mathematical algorithms? Research has shown that people have a strong cognitive tendency to imbue humanlike mental states to nonhuman entities (i.e., anthropomorphism). The present research tested whether anthropomorphizing slot machines would increase gambling. Four studies manipulated slot machine anthropomorphization and found that exposing people to an anthropomorphized description of a slot machine increased gambling behavior and reduced gambling outcomes. Such findings emerged using tasks that focused on gambling behavior (Studies 1 to 3) as well as in experimental paradigms that included gambling outcomes (Studies 2 to 4). We found that gambling outcomes decrease because participants primed with the anthropomorphic slot machine gambled more (Study 4). Furthermore, we found that high-arousal positive emotions (e.g., feeling excited) played a role in the effect of anthropomorphism on gambling behavior (Studies 3 and 4). Our research indicates that the psychological process of gambling-machine anthropomorphism can be advantageous for the gaming industry; however, this may come at great expense for gamblers' (and their families') economic resources and psychological well-being. (c) 2015 APA, all rights reserved).

APPLICATION OF QUEUING THEORY TO AUTOMATED TELLER MACHINE (ATM) FACILITIES USING MONTE CARLO SIMULATION

OpenAIRE

UDOANYA RAYMOND MANUEL; ANIEKAN OFFIONG

2014-01-01

This paper presents the importance of applying queuing theory to the Automated Teller Machine (ATM) using Monte Carlo Simulation in order to determine, control and manage the level of queuing congestion found within the Automated Teller Machine (ATM) centre in Nigeria and also it contains the empirical data analysis of the queuing systems obtained at the Automated Teller Machine (ATM) located within the Bank premises for a period of three (3) months. Monte Carlo Simulation is applied to th...

Operating experiences of reactor shutdown system at MAPS

International Nuclear Information System (INIS)

Kotteeswaran, T.J.; Subramani, V.A.; Hariharan, K.

1997-01-01

The reactors in Madras Atomic Power Station (MAPS), Kalpakkam are Pressurised Heavy Water Reactors (PHWR) similar to RAPS, Kota. The moderator heavy water is pumped into the calandria from dump tank to make the reactor critical. Later with the calandria level held constant at 92% FT, the further power changes are being done with the movement of adjuster rods. The moderator is held in calandria by means of helium gas pressure differential between top of calandria and dump tank located below. The shutdown of the reactor is effected by dumping the moderator water to dump tank by fast equalizing of helium gas pressure. In the revised mode of operation of moderator circuit after the moderator inlet manifold failure, the dump timing was observed to be more compared to the normal value. This was investigated and observed to be due to accumulation of D 2 O in the gas space above dump valves, which was affecting the helium equalizing flow. Also some of Indicating Alarm Meters (IAM) in protective system initiating the trip signals have failed in the unsafe mode. They have been modified to avoid the recurrence of the failures. (author)

Code-expanded radio access protocol for machine-to-machine communications

DEFF Research Database (Denmark)

Thomsen, Henning; Kiilerich Pratas, Nuno; Stefanovic, Cedomir

2013-01-01

The random access methods used for support of machine-to-machine, also referred to as Machine-Type Communications, in current cellular standards are derivatives of traditional framed slotted ALOHA and therefore do not support high user loads efficiently. We propose an approach that is motivated b...... subframes and orthogonal preambles, the amount of available contention resources is drastically increased, enabling the massive support of Machine-Type Communication users that is beyond the reach of current systems.......The random access methods used for support of machine-to-machine, also referred to as Machine-Type Communications, in current cellular standards are derivatives of traditional framed slotted ALOHA and therefore do not support high user loads efficiently. We propose an approach that is motivated...... by the random access method employed in LTE, which significantly increases the amount of contention resources without increasing the system resources, such as contention subframes and preambles. This is accomplished by a logical, rather than physical, extension of the access method in which the available system...

AC machine control : robust and sensorless control by parameter independency

Energy Technology Data Exchange (ETDEWEB)

Samuelsen, Dag Andreas Hals

2009-06-15

In this thesis it is first presented how robust control can be used to give AC motor drive systems competitive dynamic performance under parameter variations. These variations are common to all AC machines, and are a result of temperature change in the machine, and imperfect machine models. This robust control is, however, dependent on sensor operation in the sense that the rotor position is needed in the control loop. Elimination of this control loop has been for many years, and still is, a main research area of AC machines control systems. An integrated PWM modulator and sampler unit has been developed and tested. The sampler unit is able to give current and voltage measurements with a reduced noise component. It is further used to give the true derivative of currents and voltages in the machine and the power converter, as an average over a PWM period, and as separate values for all states of the power converter. In this way, it can give measurements of the currents as well as the derivative of the currents, at the start and at the end of a single power inverter state. This gave a large degree of freedom in parameter and state identification during uninterrupted operation of the induction machine. The special measurement scheme of the system achieved three main goals: By avoiding the time frame where the transistors commutate and the noise in the measurement of the current is large, filtering of the current measurement is no longer needed. The true derivative of the current in the machine is can be measured with far less noise components. This was extended to give any separate derivative in all three switching states of the power converter. Using the computational resources of the FPGA, more advanced information was supplied to the control system, in order to facilitate sensor less operation, with low computational demands on the DSP. As shown in the papers, this extra information was first used to estimate some of the states of the machine, in some or all of the

Zeeman catastrophe machines as a toolkit for teaching chaos

International Nuclear Information System (INIS)

Nagy, Péter; Tasnádi, Péter

2014-01-01

The investigation of chaotic motions and cooperative systems offers a magnificent opportunity to involve modern physics in the basic course of mechanics taught to engineering students. In this paper, it will be demonstrated that the Zeeman machine can be a versatile and motivating tool for students to acquire introductory knowledge about chaotic motion via interactive simulations. The Zeeman catastrophe machine is a typical example of a quasi-static system with hysteresis. It works in a relatively simple way and its properties can be understood very easily. Since the machine can be built easily and the simulation of its movement is also simple, the experimental investigation and the theoretical description can be connected intuitively. Although the Zeeman machine is known mainly for its quasi-static and catastrophic behaviour, its dynamic properties are also of interest with its typical chaotic features. By means of a periodically driven Zeeman machine, a wide range of chaotic properties of the simple systems can be demonstrated, such as bifurcation diagrams, chaotic attractors, transient chaos, Lyapunov exponents and so on. This paper is organically linked to our website (http://csodafizika.hu/zeeman) where the discussed simulation programs can be downloaded. In a second paper, the novel construction of a network of Zeeman machines will be presented to study the properties of cooperative systems. (paper)

Study on Gap Flow Field Simulation in Small Hole Machining of Ultrasonic Assisted EDM

Science.gov (United States)

Liu, Yu; Chang, Hao; Zhang, Wenchao; Ma, Fujian; Sha, Zhihua; Zhang, Shengfang

2017-12-01

When machining a small hole with high aspect ratio in EDM, it is hard for the flushing liquid entering the bottom gap and the debris could hardly be removed, which results in the accumulation of debris and affects the machining efficiency and machining accuracy. The assisted ultrasonic vibration can improve the removal of debris in the gap. Based on dynamics simulation software Fluent, a 3D model of debris movement in the gap flow field of EDM small hole machining assisted with side flushing and ultrasonic vibration is established in this paper. When depth to ratio is 3, the laws of different amplitudes and frequencies on debris distribution and removal are quantitatively analysed. The research results show that periodic ultrasonic vibration can promote the movement of debris, which is beneficial to the removal of debris in the machining gap. Compared to traditional small hole machining in EDM, the debris in the machining gap is greatly reduced, which ensures the stability of machining process and improves the machining efficiency.

Lessons learned from the ATLAS performance studies of the Iberian Cloud for the first LHC running period.

CERN Document Server

Sánchez-Martínez, V; The ATLAS collaboration; Borrego, C; del Peso, J; Delfino, M; Gomes, J; González de la Hoz, S; Pacheco Pages, A; Salt, J; Sedov, A; Villaplana, M; Wolters, H

2013-01-01

In this contribution we describe the performance of the Iberian (Spain and Portugal) ATLAS cloud during the first LHC running period (March 2010-January 2013) in the context of the GRID Computing and Data Distribution Model. The evolution of the resources for CPU, disk and tape in the Iberian Tier-1 and Tier-2s is summarized. The data distribution over all ATLAS destinations is shown, focusing on the number of files transferred and the size of the data. The status and distribution of simulation and analysis jobs within the cloud are discussed. The Distributed Analysis tools used to perform physics analysis are explained as well. Cloud performance in terms of the availability and reliability of its sites is discussed. The e ffect of the changes in the ATLAS Computing Model on the cloud is analyzed. Finally, the readiness of the Iberian Cloud towards the fi rst Long Shutdown (LS1) is evaluated and an outline of the foreseen actions to take in the coming years is given. The shutdown will be a good opportunity to...

Proceedings of Chamonix 2012 workshop on LHC Performance

International Nuclear Information System (INIS)

Carli, C.

2012-01-01

During this workshop on LHC performance, operation of the machine in 2012, activities during the first long shutdown LS1 aiming at preparing for operation at 7 TeV per beam and substantial long term upgrades of both the injector chain and the LHC have been discussed. After a session dedicated to observations and lessons from the run 2011, strategies for the run 2012 have been discussed in order to optimize the machine performance and, in particular, the maximum and integrated luminosity provided to the main experiments. Two session were dedicated to the preparation of the first long shutdown (LS1) followed by a session aiming at optimizing the performance to be expected after this first shutdown. The last two session of the workshop were dedicated to substantial upgrades of the injector complex and the LHC aiming at increasing the integrated luminosity to 250 inverse femto-barn per year after implementation in a second long shutdown. Improvements of the injector complex comprise increased injection energies in the PS Booster and the PS, an upgrade of the SPS vacuum chamber to alleviate limitations due to electron cloud build up and many more upgrades required for the generation of beams with higher brightness and smaller emittances than possible with the present machines. Plans for the LHC comprise an upgrade of the interaction regions to allow for a smaller beta*, crab cavities for luminosity levelling and, upgrades of the collimation and other systems

Selection of equipment for safe shutdown in the event of earthquake

International Nuclear Information System (INIS)

Romano Gomez, J.; Perez Alcaniz, T.; Esteban Barriendos, M.

1993-01-01

This paper presents the work carried out at the Almaraz Nuclear Power Plant for selecting equipment that contributes to reactor safe shutdown in the event of earthquake. The objective was to comply with the requirements defined by the US NRC in Generic Letter 87-02, 'Verification of Seismic Adequacy of Mechanical and Electrical Equipment in Operating Reactors'. The analysis framework and the method applied followed the generic procedures prepared by the Seismic Qualification Utility Group of which Almaraz NPP is a member, along with other Spanish power plants. The equipment selected shall be subjected to the Application Programme of the above-mentioned Generic Letter. The aim has been to cover the objectives of the programme and, at the same time, to ensure compatibility with plant operating procedures. (author)

Powering CERN and the LHC

CERN Multimedia

CERN Bulletin

2011-01-01

CERN's electricity network is denser than that of the Canton of Geneva, is powered by two different national grids and has to provide users with an availability rate as close to 100% as possible. To ensure the smooth running of the machines throughout the period of LHC physics operation, the teams from the EN Department are implementing a continuous programme of consolidation and modernisation on all the Laboratory's sites, but the biggest projects will have to wait until the long technical shutdown scheduled for 2013.   An electrical installation at CERN. CERN's annual electricity consumption is around one terawatt hour (TWh), which roughly corresponds to a fifth of the consumption of the Canton of Geneva. However, during periods when all the machines are operating at the same time, our demand can reach the equivalent of a third of Geneva's total consumption. While the grid of the Geneva public utility company SIG (Services Industriels de Genève) covers distances of around 50 km, the ...

Complement of existing ASAMPSA2 guidance for Level 2 PSA for shutdown states of reactors, Spent Fuel Pool and recent R and D results

International Nuclear Information System (INIS)

Kumar, M.; Olsson, A.; Loeffler, H.; Morandi, S.; Gumenyuk, D.; Dejardin, P.; Yu, S.; Jan, P.; Kubicek, J.; Serrano, C.; Raimond, E.; Dirksen, G.; Ivanov, I.; Groudev, P.; Kowal, K.; Prosek, Andrej; Nitoi, M.; Vitazkova, J.; Hirata, K.; Burgazzi, L.

2016-01-01

This report can be considered as an addendum to the existing ASAMPSA2 guidance for Level 2 PSA. It provides complementary guidance for Level 2 PSA for accident in the NPP shutdown states and on spent fuel pool and comments on the importance of these accidents on nuclear safety. It includes also information on recent research and development useful for Level 2 PSA developments. The conclusions of the ASAMPSA-E end-users survey and of technical meetings of WP10, WP21, WP22, and WP30 at Vienna University in September 2014 which are relevant for Level 2 PSA have been reflected and are taken into account as much as it is possible with the current status of knowledge. For Level 2 PSA in shutdown states, two plant conditions are to be distinguished: - accident sequences with RPV head closed, - accident sequences with RPV head open. When the RPV head is closed, core melt accident phenomena are very similar to the sequences going on in full power mode. Therefore, the large body of guidance which is available for full power mode is basically applicable to shutdown mode with RPV closed as well. When the RPV is open, some of the L2 PSA issues become irrelevant compared to full power mode, while others come into existence. The situation is different for aspects which do not exist or which are less pronounced in sequences with RPV closed. The report also covers containment issues in shutdown states and discusses the applicability of existing guidance, potential gaps and deficiencies and recommendations are provided. For spent fuel pool accidents in Level 2 PSA, a set of issues is identified and addressed. If the spent fuel pool is located inside the containment, the potential release paths to the environment are almost the same as for core melt accidents in the RPV. If the spent fuel pool is located outside the containment, the potential release paths to the environment depend very much on plant specific properties, e.g. ventilation systems, building doors, roof under thermal

Simple machines

CERN Document Server

Graybill, George

2007-01-01

Just how simple are simple machines? With our ready-to-use resource, they are simple to teach and easy to learn! Chocked full of information and activities, we begin with a look at force, motion and work, and examples of simple machines in daily life are given. With this background, we move on to different kinds of simple machines including: Levers, Inclined Planes, Wedges, Screws, Pulleys, and Wheels and Axles. An exploration of some compound machines follows, such as the can opener. Our resource is a real time-saver as all the reading passages, student activities are provided. Presented in s

Machine performance assessment and enhancement for a hexapod machine

Energy Technology Data Exchange (ETDEWEB)

Mou, J.I. [Arizona State Univ., Tempe, AZ (United States); King, C. [Sandia National Labs., Livermore, CA (United States). Integrated Manufacturing Systems Center

1998-03-19

The focus of this study is to develop a sensor fused process modeling and control methodology to model, assess, and then enhance the performance of a hexapod machine for precision product realization. Deterministic modeling technique was used to derive models for machine performance assessment and enhancement. Sensor fusion methodology was adopted to identify the parameters of the derived models. Empirical models and computational algorithms were also derived and implemented to model, assess, and then enhance the machine performance. The developed sensor fusion algorithms can be implemented on a PC-based open architecture controller to receive information from various sensors, assess the status of the process, determine the proper action, and deliver the command to actuators for task execution. This will enhance a hexapod machine`s capability to produce workpieces within the imposed dimensional tolerances.

Superconducting rotating machines

International Nuclear Information System (INIS)

Smith, J.L. Jr.; Kirtley, J.L. Jr.; Thullen, P.

1975-01-01

The opportunities and limitations of the applications of superconductors in rotating electric machines are given. The relevant properties of superconductors and the fundamental requirements for rotating electric machines are discussed. The current state-of-the-art of superconducting machines is reviewed. Key problems, future developments and the long range potential of superconducting machines are assessed

Evolution of the ATLAS distributed computing system during the LHC long shutdown

Science.gov (United States)

Campana, S.; Atlas Collaboration

2014-06-01

The ATLAS Distributed Computing project (ADC) was established in 2007 to develop and operate a framework, following the ATLAS computing model, to enable data storage, processing and bookkeeping on top of the Worldwide LHC Computing Grid (WLCG) distributed infrastructure. ADC development has always been driven by operations and this contributed to its success. The system has fulfilled the demanding requirements of ATLAS, daily consolidating worldwide up to 1 PB of data and running more than 1.5 million payloads distributed globally, supporting almost one thousand concurrent distributed analysis users. Comprehensive automation and monitoring minimized the operational manpower required. The flexibility of the system to adjust to operational needs has been important to the success of the ATLAS physics program. The LHC shutdown in 2013-2015 affords an opportunity to improve the system in light of operational experience and scale it to cope with the demanding requirements of 2015 and beyond, most notably a much higher trigger rate and event pileup. We will describe the evolution of the ADC software foreseen during this period. This includes consolidating the existing Production and Distributed Analysis framework (PanDA) and ATLAS Grid Information System (AGIS), together with the development and commissioning of next generation systems for distributed data management (DDM/Rucio) and production (Prodsys-2). We will explain how new technologies such as Cloud Computing and NoSQL databases, which ATLAS investigated as R&D projects in past years, will be integrated in production. Finally, we will describe more fundamental developments such as breaking job-to-data locality by exploiting storage federations and caches, and event level (rather than file or dataset level) workload engines.

Evolution of the ATLAS distributed computing system during the LHC long shutdown

International Nuclear Information System (INIS)

Campana, S

2014-01-01

The ATLAS Distributed Computing project (ADC) was established in 2007 to develop and operate a framework, following the ATLAS computing model, to enable data storage, processing and bookkeeping on top of the Worldwide LHC Computing Grid (WLCG) distributed infrastructure. ADC development has always been driven by operations and this contributed to its success. The system has fulfilled the demanding requirements of ATLAS, daily consolidating worldwide up to 1 PB of data and running more than 1.5 million payloads distributed globally, supporting almost one thousand concurrent distributed analysis users. Comprehensive automation and monitoring minimized the operational manpower required. The flexibility of the system to adjust to operational needs has been important to the success of the ATLAS physics program. The LHC shutdown in 2013-2015 affords an opportunity to improve the system in light of operational experience and scale it to cope with the demanding requirements of 2015 and beyond, most notably a much higher trigger rate and event pileup. We will describe the evolution of the ADC software foreseen during this period. This includes consolidating the existing Production and Distributed Analysis framework (PanDA) and ATLAS Grid Information System (AGIS), together with the development and commissioning of next generation systems for distributed data management (DDM/Rucio) and production (Prodsys-2). We will explain how new technologies such as Cloud Computing and NoSQL databases, which ATLAS investigated as R and D projects in past years, will be integrated in production. Finally, we will describe more fundamental developments such as breaking job-to-data locality by exploiting storage federations and caches, and event level (rather than file or dataset level) workload engines.

Energy of the LHC after the 2013-2014 shutdown

International Nuclear Information System (INIS)

Todesco, E.; Lorin, C.; Bajko, M.

2012-01-01

In 2008 all the LHC main dipole circuits were trained to 5 TeV, two sectors to 6 TeV, and one sector was pushed up to 6.6 TeV. In the 5-6 TeV range, a few quenches were needed to retrain the LHC dipoles, and none for the quadrupoles. On the other hand, in the 6- 7 TeV range a larger than expected number of quenches was observed in the main dipoles. Using this limited set of data, tentative estimates were given to guess the number of quenches needed to reach nominal energy. After three years, the only additional experimental data are the retraining of the magnets individually tested at SM18, either coming from the spares or from the 3-4 sector. After presenting this additional information, we will consider the different scenarios that can be envisaged to train the LHC main magnets after the Long Shut-down 1 (LS1), the expected energy, the impact on the commissioning time and the associated risk. (authors)

Advanced wind turbine with lift-destroying aileron for shutdown

Science.gov (United States)

Coleman, Clint; Juengst, Theresa M.; Zuteck, Michael D.

1996-06-18

An advanced aileron configuration for wind turbine rotors featuring an aileron with a bottom surface that slopes upwardly at an angle toward the nose region of the aileron. The aileron rotates about a center of rotation which is located within the envelope of the aileron, but does not protrude substantially into the air flowing past the aileron while the aileron is deflected to angles within a control range of angles. This allows for strong positive control of the rotation of the rotor. When the aileron is rotated to angles within a shutdown range of deflection angles, lift-destroying, turbulence-producing cross-flow of air through a flow gap, and turbulence created by the aileron, create sufficient drag to stop rotation of the rotor assembly. The profile of the aileron further allows the center of rotation to be located within the envelope of the aileron, at or near the centers of pressure and mass of the aileron. The location of the center of rotation optimizes aerodynamically and gyroscopically induced hinge moments and provides a fail safe configuration.

Sustainable machining

CERN Document Server

2017-01-01

This book provides an overview on current sustainable machining. Its chapters cover the concept in economic, social and environmental dimensions. It provides the reader with proper ways to handle several pollutants produced during the machining process. The book is useful on both undergraduate and postgraduate levels and it is of interest to all those working with manufacturing and machining technology.

Revisiting the analysis of passive plasma shutdown during an ex-vessel loss of coolant accident in ITER blanket

International Nuclear Information System (INIS)

Rivas, J.C.; Dies, J.; Fajarnés, X.

2015-01-01

Highlights: • We have repeated the safety analysis for the hypothesis of passive plasma shutdown for beryllium evaporation during an ex-vessel LOCA of ITER first wall, with AINA code. • We have performed a sensitivity analysis over some key parameters that represents uncertainties in physics and engineering, to identify cliff edge effects. • The obtained results for the 500 MW inductive scenario, with an ex-vessel LOCA affecting a third of first wall surface are similar to those of previous studies and point to the possibility of a passive plasma shutdown during this safety case, before a serious damage is inflicted to the ITER wall. • The sensitivity analysis revealed a new scenario potentially damaging for the first wall if we increase fusion power and time delay for impurity transport, and decrease fraction of affected first wall area and initial beryllium fraction in plasma. • After studying the 700 MW inductive scenario, with an ex-vessel LOCA affecting 10% of first wall surface, with 0.5% of Be in plasma and a time delay twice the energy confinement time, it was found that affected area of first wall would melt before a passive plasma shutdown occurs. - Abstract: In this contribution, the analysis of passive safety during an ex-vessel loss of coolant accident (LOCA) in the first wall/shield blanket of ITER has been studied with AINA safety code. In the past, this case has been studied using robust safety arguments, based on simple 0D models for plasma balance equations and 1D models for wall heat transfer. The conclusion was that, after first wall heating up due to the loss of all coolant, the beryllium evaporation in the wall surface would induce a growing impurity flux into core plasma that finally would end in a passive shut down of the discharge. The analysis of plasma-wall transients in this work is based in results from AINA code simulations. AINA (Analyses of IN vessel Accidents) code is a safety code developed at Fusion Energy Engineering

The development of management information systems for running machines at full potential

Energy Technology Data Exchange (ETDEWEB)

Steel, W.T.

1988-08-01

Statistics show that in the UK in the month of March 1988, coal face machines ran on average 114 minutes per machine shift. The average for the financial year 1987/88 was 110 minutes, which was 34% of available time. Since January 1986, machine available time has been held at around 320 min. During the same period, however, machine running time has remained static also even though several hundred million pounds has been invested in heavy duty equipment, and the number of retreat faces as a percentage of the total number in operation has increased. Our machines generally are operating at less than 50% of potential, potential being defined as the output produced if the machines operate at the expected rate, and stop only for the expected turn-round time. These statistics are derived from method study standards, which are perhaps open to challenge, but on these norms, one extra minute of machine running time per machine shift throughout the industry in the year 1987/88 would have produced about 26 million pounds of extra revenue. Although the statistics are generalisations, they demonstrate not only the problem to which the industry must address itself if it is to be competitive but also the scope which is available for improvements. 5 figs.

Advanced Electrical Machines and Machine-Based Systems for Electric and Hybrid Vehicles

Directory of Open Access Journals (Sweden)

Ming Cheng

2015-09-01

Full Text Available The paper presents a number of advanced solutions on electric machines and machine-based systems for the powertrain of electric vehicles (EVs. Two types of systems are considered, namely the drive systems designated to the EV propulsion and the power split devices utilized in the popular series-parallel hybrid electric vehicle architecture. After reviewing the main requirements for the electric drive systems, the paper illustrates advanced electric machine topologies, including a stator permanent magnet (stator-PM motor, a hybrid-excitation motor, a flux memory motor and a redundant motor structure. Then, it illustrates advanced electric drive systems, such as the magnetic-geared in-wheel drive and the integrated starter generator (ISG. Finally, three machine-based implementations of the power split devices are expounded, built up around the dual-rotor PM machine, the dual-stator PM brushless machine and the magnetic-geared dual-rotor machine. As a conclusion, the development trends in the field of electric machines and machine-based systems for EVs are summarized.

Asynchronized synchronous machines

CERN Document Server

Botvinnik, M M

1964-01-01

Asynchronized Synchronous Machines focuses on the theoretical research on asynchronized synchronous (AS) machines, which are "hybrids” of synchronous and induction machines that can operate with slip. Topics covered in this book include the initial equations; vector diagram of an AS machine; regulation in cases of deviation from the law of full compensation; parameters of the excitation system; and schematic diagram of an excitation regulator. The possible applications of AS machines and its calculations in certain cases are also discussed. This publication is beneficial for students and indiv

The efficacy of support vector machines (SVM)

Indian Academy of Sciences (India)

(2006) by applying an SVM statistical learning machine on the time-scale wavelet decomposition methods. We used the data of 108 events in central Japan with magnitude ranging from 3 to 7.4 recorded at KiK-net network stations, for a source–receiver distance of up to 150 km during the period 1998–2011. We applied a ...

Machine Shop Lathes.

Science.gov (United States)

Dunn, James

This guide, the second in a series of five machine shop curriculum manuals, was designed for use in machine shop courses in Oklahoma. The purpose of the manual is to equip students with basic knowledge and skills that will enable them to enter the machine trade at the machine-operator level. The curriculum is designed so that it can be used in…

Station blackout with failure of wired shutdown system for AHWR

International Nuclear Information System (INIS)

Srivastava, A.; Contractor, A.D.; Chatterjee, B.; Kumar, Rajesh

2015-01-01

Advanced Heavy Water Reactor (AHWR) is a vertical pressure tube type boiling light water cooled and heavy water moderated reactor. This reactor has several advance safety features. One of the important passive design features of this reactor is that the heat removal is achieved through natural circulation of primary coolant at all power level without primary coolant pumps. Station blackout (SBO) scenario has become very important in aftermath of Fukushima event. The existing reactor has to demonstrate that design features are sufficient to mitigate the scenario whereas the new reactor design are adding specific features to tackle such scenario for prolonged period. The present study demonstrates the design features of AHWR to mitigate the SBO scenario along with failure of wired shutdown system. SBO event leads to feed water pump trip and loss of condenser vacuum which in turn results into loss of feed water and turbine trip on low condenser vacuum signal. Stoppage of steam flow to the turbine and bypass to the condenser lead to bottling up of the system, causing MHT pressure to rise. In the absence of reactor scram, the pressure continues to rise. Isolation Condenser (IC) valve starts opening at a pressure of 7.65 MPa. The pressure continues to rise as IC system is designed for decay heat removal and reactor power is brought down to decay power level through Passive Poison Injection System (PPIS) when the pressure reaches 8.4 MPa. The analysis shows that the event do not lead to undesirable clad surface temperature rise due to reactor trip by PPIS and decay heat removal for prolonged time by IC system. Thermal hydraulic response of different parameters like pressure, temperatures, and flows in MHT system is analyzed for this scenario. Pressure during transient is found to be well below the system pressure criteria of 110% of design pressure. This analysis highlights the design robustness of AHWR. (author)

Predicting genome-wide redundancy using machine learning

Directory of Open Access Journals (Sweden)

Shasha Dennis E

2010-11-01

Full Text Available Abstract Background Gene duplication can lead to genetic redundancy, which masks the function of mutated genes in genetic analyses. Methods to increase sensitivity in identifying genetic redundancy can improve the efficiency of reverse genetics and lend insights into the evolutionary outcomes of gene duplication. Machine learning techniques are well suited to classifying gene family members into redundant and non-redundant gene pairs in model species where sufficient genetic and genomic data is available, such as Arabidopsis thaliana, the test case used here. Results Machine learning techniques that combine multiple attributes led to a dramatic improvement in predicting genetic redundancy over single trait classifiers alone, such as BLAST E-values or expression correlation. In withholding analysis, one of the methods used here, Support Vector Machines, was two-fold more precise than single attribute classifiers, reaching a level where the majority of redundant calls were correctly labeled. Using this higher confidence in identifying redundancy, machine learning predicts that about half of all genes in Arabidopsis showed the signature of predicted redundancy with at least one but typically less than three other family members. Interestingly, a large proportion of predicted redundant gene pairs were relatively old duplications (e.g., Ks > 1, suggesting that redundancy is stable over long evolutionary periods. Conclusions Machine learning predicts that most genes will have a functionally redundant paralog but will exhibit redundancy with relatively few genes within a family. The predictions and gene pair attributes for Arabidopsis provide a new resource for research in genetics and genome evolution. These techniques can now be applied to other organisms.

Machining of a bioactive nanocomposite orthopedic fixation device.

Science.gov (United States)

Sparnell, Amie; Aniket; El-Ghannam, Ahmed

2012-08-01

Bioactive ceramics bond to bone and enhance bone formation. However, they have poor mechanical properties which restrict their machinability as well as their application as load bearing implants. The goal of this study was to machine bioactive fixation screws using a silica-calcium phosphate nanocomposite (SCPC50). The effect of compact pressure, holding time, and thermal treatment on the microstructure, machinability, and mechanical properties of SCPC50 cylinders were investigated. Samples prepared by powder metallurgy technique at compact pressure range of 100-300 MPa and treated at 900°C/1 h scored a poor machinability rating of (1/5) due to the significant formation of amorphous silicate phase at the grain boundaries. On the other hand, lowering of compact pressure and sintering temperature to 30 MPa/3 h and 700°C/2 h, respectively, minimized the formation of the amorphous phase and raised the machinability rating to (5/5). The modulus of elasticity and ultimate strength of machinable SCPC50 were 10.8 ± 2.0 GPa and 72.8 ± 22.8 MPa, respectively, which are comparable to the corresponding values for adult human cortical bone. qRT-PCR analyses showed that bone cells attached to SCPC50 significantly upregulated osteocalcin mRNA expression as compared to the cells on Ti-6Al-4V. Moreover, cells attached to SCPC50 produced mineralized bone-like tissue within 8 days. On the other hand, cells attached to Ti-6Al-4V failed to produce bone mineral under the same experimental conditions. Results of the study suggest that machinable SCPC50 has the potential to serve as an attractive new material for orthopedic fixation devices. Copyright © 2012 Wiley Periodicals, Inc.

Shutdown dose rate analysis with CAD geometry, Cartesian/tetrahedral mesh, and advanced variance reduction

International Nuclear Information System (INIS)

Biondo, Elliott D.; Davis, Andrew; Wilson, Paul P.H.

2016-01-01

Highlights: • A CAD-based shutdown dose rate analysis workflow has been implemented. • Cartesian and superimposed tetrahedral mesh are fully supported. • Biased and unbiased photon source sampling options are available. • Hybrid Monte Carlo/deterministic techniques accelerate photon transport. • The workflow has been validated with the FNG-ITER benchmark problem. - Abstract: In fusion energy systems (FES) high-energy neutrons born from burning plasma activate system components to form radionuclides. The biological dose rate that results from photons emitted by these radionuclides after shutdown—the shutdown dose rate (SDR)—must be quantified for maintenance planning. This can be done using the Rigorous Two-Step (R2S) method, which involves separate neutron and photon transport calculations, coupled by a nuclear inventory analysis code. The geometric complexity and highly attenuating configuration of FES motivates the use of CAD geometry and advanced variance reduction for this analysis. An R2S workflow has been created with the new capability of performing SDR analysis directly from CAD geometry with Cartesian or tetrahedral meshes and with biased photon source sampling, enabling the use of the Consistent Adjoint Driven Importance Sampling (CADIS) variance reduction technique. This workflow has been validated with the Frascati Neutron Generator (FNG)-ITER SDR benchmark using both Cartesian and tetrahedral meshes and both unbiased and biased photon source sampling. All results are within 20.4% of experimental values, which constitutes satisfactory agreement. Photon transport using CADIS is demonstrated to yield speedups as high as 8.5·10"5 for problems using the FNG geometry.

Chaotic behaviour of Zeeman machines at introductory course of mechanics

Science.gov (United States)

Nagy, Péter; Tasnádi, Péter

2016-05-01

Investigation of chaotic motions and cooperative systems offers a magnificent opportunity to involve modern physics into the basic course of mechanics taught to engineering students. In the present paper it will be demonstrated that Zeeman Machine can be a versatile and motivating tool for students to get introductory knowledge about chaotic motion via interactive simulations. It works in a relatively simple way and its properties can be understood very easily. Since the machine can be built easily and the simulation of its movement is also simple the experimental investigation and the theoretical description can be connected intuitively. Although Zeeman Machine is known mainly for its quasi-static and catastrophic behaviour, its dynamic properties are also of interest with its typical chaotic features. By means of a periodically driven Zeeman Machine a wide range of chaotic properties of the simple systems can be demonstrated such as bifurcation diagrams, chaotic attractors, transient chaos and so on. The main goal of this paper is the presentation of an interactive learning material for teaching the basic features of the chaotic systems through the investigation of the Zeeman Machine.

Joint optimization of maintenance, buffers and machines in manufacturing lines

Science.gov (United States)

Nahas, Nabil; Nourelfath, Mustapha

2018-01-01

This article considers a series manufacturing line composed of several machines separated by intermediate buffers of finite capacity. The goal is to find the optimal number of preventive maintenance actions performed on each machine, the optimal selection of machines and the optimal buffer allocation plan that minimize the total system cost, while providing the desired system throughput level. The mean times between failures of all machines are assumed to increase when applying periodic preventive maintenance. To estimate the production line throughput, a decomposition method is used. The decision variables in the formulated optimal design problem are buffer levels, types of machines and times between preventive maintenance actions. Three heuristic approaches are developed to solve the formulated combinatorial optimization problem. The first heuristic consists of a genetic algorithm, the second is based on the nonlinear threshold accepting metaheuristic and the third is an ant colony system. The proposed heuristics are compared and their efficiency is shown through several numerical examples. It is found that the nonlinear threshold accepting algorithm outperforms the genetic algorithm and ant colony system, while the genetic algorithm provides better results than the ant colony system for longer manufacturing lines.

Chaotic behaviour of Zeeman machines at introductory course of mechanics

International Nuclear Information System (INIS)

Nagy, P.; Tasnádi, P.

2015-01-01

Investigation of chaotic motions and cooperative systems offers a magnificent opportunity to involve modern physics into the basic course of mechanics taught to engineering students. In the present paper it will be demonstrated that Zeeman Machine can be a versatile and motivating tool for students to get introductory knowledge about chaotic motion via interactive simulations. It works in a relatively simple way and its properties can be understood very easily. Since the machine can be built easily and the simulation of its movement is also simple the experimental investigation and the theoretical description can be connected intuitively. Although Zeeman Machine is known mainly for its quasi-static and catastrophic behaviour, its dynamic properties are also of interest with its typical chaotic features. By means of a periodically driven Zeeman Machine a wide range of chaotic properties of the simple systems can be demonstrated such as bifurcation diagrams, chaotic attractors, transient chaos and so on. The main goal of this paper is the presentation of an interactive learning material for teaching the basic features of the chaotic systems through the investigation of the Zeeman Machine. 1. –

Risk contribution from low power and shutdown of a pressurized water reactor

International Nuclear Information System (INIS)

Chu, T.L.; Pratt, W.T.

1997-01-01

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 operation 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 PRA for traditional internal events and a Level 1 PRA on fire, flooding, and seismically induced core damage sequences. 12 refs., 7 tabs

Performance of the NRX shut-off rods

International Nuclear Information System (INIS)

Manson, R.E.

1965-08-01

A new type of shut-off rod of electromechanical design was developed by the American Machine and Foundry Company for use in the NRX reactor following the accident of 1952. The new rods were installed in May, 1956, as part of the control system conversion program which was completed in 1958. Some problems were encountered with limit switch adjustment but minor modifications in design led to much improved operation. he performance of the rods also improved as more experience was gained in the maintenance and adjustment of the various headgear components. Each headgear is now overhauled once a year on a routine basis. The present design of shut-off rod is considered to be very satisfactory. There has only been one occasion when a shut-off rod has failed to come fully down on a trip. Rods have failed to operate correctly on five other occasions but these occurred during shutdown periods or when the reactor was being shutdown manually. (author)

Estimation of the profile of cross-machine shrinkage of paper

International Nuclear Information System (INIS)

I'Anson, S J; Sampson, W W; Constantino, R P A; Hoole, S M

2008-01-01

In common with many other materials, paper tends to shrink as it dries. Although every attempt is made to restrain paper, some shrinkage occurs on all paper machines in the direction perpendicular to that of manufacture and this shrinkage is always much higher at the edges of the machine than in the centre. Measurement of the profile of this cross-machine shrinkage is possible using the fast Fourier transform to locate and measure periodic elements imprinted by the filtration fabrics used during the formation of the paper web. This paper describes a new method which allows the geometrical relationships within the fabric to be used along with dimensional changes to estimate shrinkage. The method has the advantages over previous methods of more tolerant sampling protocols, operator independent analysis and improved accuracy

Timer-based data acquisitioning of creep testing machines

International Nuclear Information System (INIS)

Rana, M.A.; Farooq, M.A.; Ali, L.

1998-01-01

Duration of a creep test may be short or long term extending over several years. Continuous operation of a computer for automatic data acquisition of creep testing machines is useless. Timer based data acquisitioning of the machines already interface with IBM-Pc/AT and compatibles has been streamlined for economical use of the computer. A locally designed and fabricated timer has been introduced in the system in this regard to meet the requirements of the system. The timer switches on the computer according to pre scheduled interval of time of capture creep data in Real time. The periodically captured data is logged on the hard disk for analysis and report generation. (author)

Questions and answers about the reactor shutdown at the Barsebaeck plant

International Nuclear Information System (INIS)

1992-01-01

At a scram at the Barsebaeck 2 reactor on July 28 1992, a safety valve open unintentionally, and steam was released from the reactor vessel into the containment. The emergency spray system started sprinkling the vessel (the core spray system was also active for a short while). After one hour, the sprinkling was interupted, and at about the same time it was found that the steam jet had tore off insulation material (from the containment walls) which started to clog the sieves for the emergency sprinkling water, disturbing the pumping. The clogging appeared much more rapidly than expected (1 h in stead of 10 h). Five Swedish reactors for similar design have been shutdown pending a reconstruction of the emergency spray feed system. This pamphlet is directed to the general public, explaining the problems and commenting on nuclear safety issues

Machining of Machine Elements Made of Polymer Composite Materials

Science.gov (United States)

Baurova, N. I.; Makarov, K. A.

2017-12-01

The machining of the machine elements that are made of polymer composite materials (PCMs) or are repaired using them is considered. Turning, milling, and drilling are shown to be most widely used among all methods of cutting PCMs. Cutting conditions for the machining of PCMs are presented. The factors that most strongly affect the roughness parameters and the accuracy of cutting PCMs are considered.

Mobility problems at the KNK II shut-down systems, cause investigations and valuation in comparison with the experience at other plants

International Nuclear Information System (INIS)

Hess, B.

1992-12-01

During the operation of the second core of the fast test reactor KNK II the shutdown systems showed repeatedly problems with their mobility, which also caused to be reported events. The present report gives a summary description of the events in chronological order. The investigations to remove the mobility problems and the resulting design modifications are described together with the comments of the licensing authorities on the way to the restart of the plant. The results of the post-irradiation investigations in the hot cells and of sodium-chemical investigations are also described. In addition to the comparison of the events at the KNK plant itself and a review of the experiences at comparable plants it will be shown that all known cases of mobility problems did only influence the availability of the plant but that the safe shut-down of the plant was never at risk [de

Improving Machining Accuracy of CNC Machines with Innovative Design Methods

Science.gov (United States)

Yemelyanov, N. V.; Yemelyanova, I. V.; Zubenko, V. L.

2018-03-01

The article considers achieving the machining accuracy of CNC machines by applying innovative methods in modelling and design of machining systems, drives and machine processes. The topological method of analysis involves visualizing the system as matrices of block graphs with a varying degree of detail between the upper and lower hierarchy levels. This approach combines the advantages of graph theory and the efficiency of decomposition methods, it also has visual clarity, which is inherent in both topological models and structural matrices, as well as the resiliency of linear algebra as part of the matrix-based research. The focus of the study is on the design of automated machine workstations, systems, machines and units, which can be broken into interrelated parts and presented as algebraic, topological and set-theoretical models. Every model can be transformed into a model of another type, and, as a result, can be interpreted as a system of linear and non-linear equations which solutions determine the system parameters. This paper analyses the dynamic parameters of the 1716PF4 machine at the stages of design and exploitation. Having researched the impact of the system dynamics on the component quality, the authors have developed a range of practical recommendations which have enabled one to reduce considerably the amplitude of relative motion, exclude some resonance zones within the spindle speed range of 0...6000 min-1 and improve machining accuracy.

Machinability of nickel based alloys using electrical discharge machining process

Science.gov (United States)

Khan, M. Adam; Gokul, A. K.; Bharani Dharan, M. P.; Jeevakarthikeyan, R. V. S.; Uthayakumar, M.; Thirumalai Kumaran, S.; Duraiselvam, M.

2018-04-01

The high temperature materials such as nickel based alloys and austenitic steel are frequently used for manufacturing critical aero engine turbine components. Literature on conventional and unconventional machining of steel materials is abundant over the past three decades. However the machining studies on superalloy is still a challenging task due to its inherent property and quality. Thus this material is difficult to be cut in conventional processes. Study on unconventional machining process for nickel alloys is focused in this proposed research. Inconel718 and Monel 400 are the two different candidate materials used for electrical discharge machining (EDM) process. Investigation is to prepare a blind hole using copper electrode of 6mm diameter. Electrical parameters are varied to produce plasma spark for diffusion process and machining time is made constant to calculate the experimental results of both the material. Influence of process parameters on tool wear mechanism and material removal are considered from the proposed experimental design. While machining the tool has prone to discharge more materials due to production of high energy plasma spark and eddy current effect. The surface morphology of the machined surface were observed with high resolution FE SEM. Fused electrode found to be a spherical structure over the machined surface as clumps. Surface roughness were also measured with surface profile using profilometer. It is confirmed that there is no deviation and precise roundness of drilling is maintained.

The achievements of the Z-machine; Les exploits de la Z-machine

Energy Technology Data Exchange (ETDEWEB)

Larousserie, D

2008-03-15

The ZR-machine that represents the latest generation of Z-pinch machines has recently begun preliminary testing before its full commissioning in Albuquerque (Usa). During its test the machine has well operated with electrical currents whose intensities of 26 million Ampere are already 2 times as high as the intensity of the operating current of the previous Z-machine. In 2006 the Z-machine reached temperatures of 2 billions Kelvin while 100 million Kelvin would be sufficient to ignite thermonuclear fusion. In fact the concept of Z-pinch machines was imagined in the fifties but the technological breakthrough that has allowed this recent success and the reborn of Z-machine, was the replacement of gas by an array of metal wires through which the electrical current flows and vaporizes it creating an imploding plasma. It is not well understood why Z-pinch machines generate far more radiation than theoretically expected. (A.C.)

Cases of coupled vibrations and prametric instability in rotating machines

OpenAIRE

Luneno, Jean-Claude

2012-01-01

The principal task in this research project was to analyse the causes and consequences of coupled vibrations and parametric instability in hydropower rotors; where both horizontal and vertical machines are involved. Vibration is a well-known undesirable behavior of dynamical systems characterised by persistent periodic, quasi-periodic or chaotic motions. Vibrations generate noise and cause fatigue, which initiates cracks in mechanical structures. Motions coupling can in some cases augment the...

Quantum machine learning.

Science.gov (United States)

Biamonte, Jacob; Wittek, Peter; Pancotti, Nicola; Rebentrost, Patrick; Wiebe, Nathan; Lloyd, Seth

2017-09-13

Fuelled by increasing computer power and algorithmic advances, machine learning techniques have become powerful tools for finding patterns in data. Quantum systems produce atypical patterns that classical systems are thought not to produce efficiently, so it is reasonable to postulate that quantum computers may outperform classical computers on machine learning tasks. The field of quantum machine learning explores how to devise and implement quantum software that could enable machine learning that is faster than that of classical computers. Recent work has produced quantum algorithms that could act as the building blocks of machine learning programs, but the hardware and software challenges are still considerable.

Containment closure time following the loss of shutdown cooling event of YGN Units 3 and 4

International Nuclear Information System (INIS)

Seul, Kwang Won; Bang, Young Seok; Kim, Hho Jung

1999-01-01

The YGN Units 3 and 4 plant conditions during shutdown operation were reviewed to identify the possible event scenarios following the loss of shutdown cooling (SDC) event. For the five cases of typical reactor coolant system (RCS) configurations under the worst event sequence, such as unavailable secondary cooling and no RCS inventory makeup, the thermal hydraulic analyses were performed using the RELAP5/MOS3.2 code to investigate the plant behavior following the event. The thermal hydraulic analyses include the estimation of time to boil, time to core uncovery, and time to core heat up to determine the containment closure time to prevent the uncontrolled release of fission products to atmosphere. The result indicates that the containment closure is recommended to be achieved within 42 minutes after the loss of SDC for the steam generator (SG) inlet plenum manway open case or the large cold leg open case under the worst event sequence. The containment closure time is significantly dependent on the elevation and size of the opening and the SG secondary water level condition. It is also found that the containment closure needs to be initiated before the boiling time to ensure the survivability of the workers in the containment. These results will provide using information to operators to cope with the loss of SDC event. (Author). 15 refs., 3 tabs., 7 figs