WorldWideScience

Sample records for valve closing fuel

  1. Modeling and control of fuel distribution in a dual-fuel internal combustion engine leveraging late intake valve closings

    Energy Technology Data Exchange (ETDEWEB)

    Kassa, Mateos [Mechanical, Materials, and Aerospace Engineering Department, Illinois Institute of Technology, Chicago, IL, USA; Hall, Carrie [Mechanical, Materials, and Aerospace Engineering Department, Illinois Institute of Technology, Chicago, IL, USA; Ickes, Andrew [Fuels, Engine and Aftertreatment Research, Argonne National Laboratory, Argonne, IL, USA; Wallner, Thomas [Fuels, Engine and Aftertreatment Research, Argonne National Laboratory, Argonne, IL, USA

    2016-10-07

    Advanced internal combustion engines, although generally more efficient than conventional combustion engines, often encounter limitations in multi-cylinder applications due to variations in the combustion process encountered across cylinders and between cycles. This study leverages experimental data from an inline 6-cylinder heavy-duty dual fuel engine equipped with exhaust gas recirculation (EGR), a variable geometry turbocharger, and a fully-flexible variable intake valve actuation system to study cylinder-to-cylinder variations in power production and the underlying uneven fuel distribution that causes these variations. The engine is operated with late intake valve closure timings in a dual-fuel combustion mode in which a high reactivity fuel is directly injected into the cylinders and a low reactivity fuel is port injected into the cylinders. Both dual fuel implementation and late intake valve closing (IVC) timings have been shown to improve thermal efficiency. However, experimental data from this study reveal that when late IVC timings are used on a multi-cylinder dual fuel engine a significant variation in IMEP across cylinders results and as such, leads to efficiency losses. The difference in IMEP between the different cylinders ranges from 9% at an IVC of 570°ATDC to 38% at an IVC of 610°ATDC and indicates an increasingly uneven fuel distribution. These experimental observations along with engine simulation models developed using GT-Power have been used to better understand the distribution of the port injected fuel across cylinders under various operating conditions on such dual fuel engines. This study revealed that the fuel distribution across cylinders in this dual fuel application is significantly affected by changes in the effective compression ratio as determined by the intake valve close timing as well as the design of the intake system (specifically the length of the intake runners). Late intake valve closures allow a portion of the trapped air

  2. Valve for closing a steam line

    International Nuclear Information System (INIS)

    Meyer, W.; Potrykus, G.

    1976-01-01

    Instead of several control elements, the quick-closing valve, especially in the main-steam line between steam generator and turbine of a power station has the valve cone itself as the only movable part, acting with its inner surface as a piston within a second cylinder space. The valve shaft is at the same time a piston rod with a stepped piston at the upper end. This piston is loaded in a cylinder at the upspace below the valve cover on one hand by a spring, on the other hand by its own medium. Two non-return valves, one of it in a bore of the valve cone, connect the first-mentioned cylinder space with the steam-loaded inlet resp. outlet side of the valve. For controlling the valve, a magnet valve is sufficient. By automatic control of the valve cone coupled with several pistons several control lines can be omitted. There are also no pressurized control lines outside the valve which could be damaged by exterior influences. (ERA) [de

  3. Safety valve opening and closing operation monitor

    International Nuclear Information System (INIS)

    Kodama, Kunio; Takeshima, Ikuo; Takahashi, Kiyokazu.

    1981-01-01

    Purpose: To enable the detection of the closing of a safety valve when the internal pressure in a BWR type reactor is a value which will close the safety valve, by inputting signals from a pressure detecting device mounted directly at a reactor vessel and a safety valve discharge pressure detecting device to an AND logic circuit. Constitution: A safety valve monitor is formed of a pressure switch mounted at a reactor pressure vessel, a pressure switch mounted at the exhaust pipe of the escape safety valve and a logic circuit and the lide. When the input pressure of the safety valve is raised so that the valve and the pressure switch mounted at the exhaust pipe are operated, an alarm is indicated, and the operation of the pressure switch mounted at a pressure vessel is eliminated. If the safety valve is not reclosed when the vessel pressure is decreased lower than the pressure at which it is to be reclosed after the safety valve is operated, an alarm is generated by the logic circuit since both the pressure switches are operated. (Sekiya, K.)

  4. 14 CFR 25.995 - Fuel valves.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fuel valves. 25.995 Section 25.995 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Fuel System Components § 25.995 Fuel valves. In addition...

  5. 14 CFR 29.995 - Fuel valves.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fuel valves. 29.995 Section 29.995 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Fuel System Components § 29.995 Fuel valves. In addition...

  6. 14 CFR 27.995 - Fuel valves.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fuel valves. 27.995 Section 27.995 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Powerplant Fuel System Components § 27.995 Fuel valves. (a) There must...

  7. 46 CFR 78.17-5 - Valves and closing appliances.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 3 2010-10-01 2010-10-01 false Valves and closing appliances. 78.17-5 Section 78.17-5..., Drills, and Inspections § 78.17-5 Valves and closing appliances. (a) It shall be the duty of the master to see that all valves, including cross connecting valves where fitted, and other appliances such as...

  8. 46 CFR 78.47-38 - Valves and closing appliances.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 3 2010-10-01 2010-10-01 false Valves and closing appliances. 78.47-38 Section 78.47-38... Fire and Emergency Equipment, Etc. § 78.47-38 Valves and closing appliances. (a) All valves and closing appliances, or other mechanisms which may be required to be operated for damage control purposes in case of...

  9. Closing the fuel cycle

    International Nuclear Information System (INIS)

    Aycoberry, C.; Rougeau, J.P.

    1987-01-01

    The progressive implementation of some key nuclear fuel cycle capecities in a country corresponds to a strategy for the acquisition of an independant energy source, France, Japan, and some European countries are engaged in such strategic programs. In France, COGEMA, the nuclear fuel company, has now completed the industrial demonstration of the closed fuel cycle. Its experience covers every step of the front-end and of the back-end: transportation of spent fuels, storage, reprocessing, wastes conditioning. The La Hague reprocessing plant smooth operation, as well as the large investment program under active progress can testify of full mastering of this industry. Together with other French and European companies, COGEMA is engaged in the recycling industry, both for uranium through conversion of uranyl nitrate for its further reeichment, and for plutonium through MOX fuel fabrication. Reprocessing and recycling offer the optimum solution for a complete, economic, safe and future-oriented fuel cycle, hence contributing to the necessary development of nuclear energy. (author)

  10. Novel passive normally closed microfluidic valve

    CSIR Research Space (South Africa)

    Land, K

    2009-09-01

    Full Text Available ’ represents the distance by which the membrane is depressed before actuation. This stretches the membrane to give it a pre-tension. Thus, when the pressure is removed from the inlet, the membrane returns to its original position, thereby closing the valve.... This also determines the pressure, pcritical, required to depress the membrane for actuation. Actuation occurs once the pressure from the input fluid reaches pcritical, the membrane is depressed and fluid flows freely from the inlet to the outlet. A...

  11. The closed fuel cycle

    International Nuclear Information System (INIS)

    Froment, Antoine; Gillet, Philippe

    2007-01-01

    Available in abstract form only. Full text of publication follows: The fast growth of the world's economy coupled with the need for optimizing use of natural resources, for energy security and for climate change mitigation make energy supply one of the 21. century most daring challenges. The high reliability and efficiency of nuclear energy, its competitiveness in an energy market undergoing a new oil shock are as many factors in favor of the 'renaissance' of this greenhouse gas free energy. Over 160,000 tHM of LWR1 and AGR2 Used Nuclear Fuel (UNF) have already been unloaded from the reactor cores corresponding to 7,000 tons discharged per year worldwide. By 2030, this amount could exceed 400,000 tHM and annual unloading 14,000 tHM/year. AREVA believes that closing the nuclear fuel cycle through the treatment and recycling of Used Nuclear Fuel sustains the worldwide nuclear power expansion. It is an economically sound and environmentally responsible choice, based on the preservation of natural resources through the recycling of used fuel. It furthermore provides a safe and secure management of wastes while significantly minimizing the burden left to future generations. (authors)

  12. Closing the fuel cycle

    International Nuclear Information System (INIS)

    Wolfe, B.; Judson, B.F.

    1984-01-01

    The possibilities for closing the fuel cycle in today's nuclear climate in the US are compared with those envisioned in 1977. Reprocessing, the fast breeder reactor program, and the uranium supply are discussed. The conclusion drawn is that the nuclear world is less healthy and less stable than the one previously envisioned and that the major task before the international nuclear community is to develop technologies, institutions, and accepted procedures that will allow to economically provide the huge store of energy from reprocessing and the breeder that it appears the world will desperately need

  13. Optimization analysis of swing check valve closing induced water hammer

    International Nuclear Information System (INIS)

    Han Wenwei; Han Weishi; Guo Qing; Wang Xin; Liu Chunyu

    2014-01-01

    A mathematical-physics model of double pump parallel feed system was constructed. The water hammer was precisely calculated, which was formed in the closing process of swing check valve. And a systematic analysis was carried out to determine the influence of the torques from both valve plate and damping torsion spring on the valve closing induced water hammer. The results show that the swing check valve would distinctly produce the water hammer during the closing procedure in the double pump parallel feed water system. The torques of the valve plate can partly reduce the water hammer effect, and implying appropriate materials of valve plate and appropriate spring can effectively relieve the harm of water hammer. (authors)

  14. Device for the simultaneous operation of the closing valve of a vessel and the closing valve of a transport container

    International Nuclear Information System (INIS)

    Tellier, Claude; Surriray, Michel.

    1982-01-01

    This device includes mechanisms for unlatching the closing valve of the vessel and securing it to the closing valve of the transport container and other mechanisms for vertically raising the assembly of valves, pivoting it and bringing it into a vertical position in a bulge provided in the bottom of the transport container. For example the first containment is a nuclear reactor vessel and the transport container is used for carrying an item from the vessel to an external area (for instance, a defective pump to the repair area) and for the return transport operation [fr

  15. Normally-Closed Zero-Leak Valve with Magnetostrictive Actuator

    Science.gov (United States)

    Ramspacher, Daniel J. (Inventor); Richard, James A. (Inventor)

    2017-01-01

    A non-pyrotechnic, normally-closed, zero-leak valve is a replacement for the pyrovalve used for both in-space and launch vehicle applications. The valve utilizes a magnetostrictive alloy for actuation, rather than pyrotechnic charges. The alloy, such as Terfenol-D, experiences magnetostriction, i.e. a gross elongation, when exposed to a magnetic field. This elongation fractures a parent metal seal, allowing fluid flow through the valve. The required magnetic field is generated by redundant coils that are isolated from the working fluid.

  16. Low intake valve lift in a port fuel-injected engine

    Energy Technology Data Exchange (ETDEWEB)

    Begg, S.M.; Hindle, M.P.; Cowell, T.; Heikal, M.R. [The Sir Harry Ricardo Laboratories, Centre for Automotive Engineering, Cockcroft Building, University of Brighton, Lewes Road, Brighton, East Sussex, BN2 4GJ (United Kingdom)

    2009-12-15

    A phenomenological study of the airflow and fuel spray interaction in a variable valve gasoline engine is presented. Experiments were performed in a steady-state flow rig fitted with a modified production cylinder head. The intake valve lift was varied manually. The mass flow rates of air and fuel through the test rig were adjusted to match typical engine operating conditions. Particle Image Velocimetry (PIV) and Laser Doppler Anemometry (LDA) measurements of the airflow showed the breakdown of a single, forward tumbling vortex-like structure into a pair of high-speed, turbulent jets at low valve lifts. Two transitional phases in the flow at the valve gap were identified for valve lifts less than 1.5 mm and greater than 3 mm. At the lower limit, a jet flapping instability was recorded. A port fuel injector (PFI) spray was characterised in a quiescent, chamber and within the test rig. High Speed Photography (HSP) and Phase Doppler Anemometry (PDA) were used to measure the effects of varying valve lift upon the fuel droplet characteristics. The in-cylinder measurements showed a reduction in mean droplet diameter of up to 50%, close to the valve gap, for peak valve lifts of less than 3 mm. (author)

  17. 49 CFR Appendix A to Part 180 - Internal Self-closing Stop Valve Emergency Closure Test for Liquefied Compressed Gases

    Science.gov (United States)

    2010-10-01

    ... internal self-closing stop valve's lever, piston, or other valve indicator has moved to the closed position. 2. On pump-actuated pressure differential internal valves, the three-way toggle valve handle or its...

  18. Rapsodie: A closed fuel cycle

    International Nuclear Information System (INIS)

    Levallet, E.H.; Costa, L.; Mougniot, J.C.; Robin, J.

    1977-01-01

    The Fortissimo Version of the core of the RAPSODIE fast reactor produces 40 MWTh. Since its start up in May 1970 in the CEN-CADARACHE its availability has stayed around 85%. Some of the mixed oxyde fuel pins UO 2 - 30% PuO 2 have already reached 150.000 MWd/t. The reprocessing is done in the pilot plant located in the La Hague Center and the plutonium obtained has already been re-used in the reactor. The Rapsodie-Fortissimo cycle is therefore now a closed cycle. This cycle is quite representative of fast reactor cycle characteristics and thus provides a remarkable research and development tool for the study of fabrication, in-reactor performances, transport, storage and reprocessing. These studies concern in particular the evolution of fission products and heavy isotopes content in fuel which controls both reprocessing schemes and intensity of emitted radiations. A program for the analysis of irradiated fuel has been developed either using samples collected all along the cycle, or following the actual reprocessing subassemblies. A set of basic data and calculation models has been established with two objectives: to give a better interpretation of the experimental program on one hand, and to extrapolate these results to the fuel cycle of fast reactors in general on the other hand. The first results have been quite encouraging up to now [fr

  19. Door valve for fuel handling path

    International Nuclear Information System (INIS)

    Makishima, Katsuhiko.

    1969-01-01

    A door valve is provided which seals cover gas from a liquid metal cooled reactor without leakage therefrom. A threaded shaft is screwed into a heavy box press which is packed with lead. The shaft is adapted to be rotated by an electric motor or a manually operated wheel which is disposed outside of the door valve. A valve plate is suspended from the box press by four guide wheels mounted thereon. The guide wheels are fitted into inclined guide grooves formed at the valve plate and into grooved formed in the inner wall of a valve casing. A locking ball is provided at each side of the valve plate. In operation the shaft rotates and travels to permit the box press and the valve plate to move into the door valve casing, thus releasing the locking balls. The valve plate does not contact the bottom of the casing. When the box press reaches the home position, the valve plate is carried on the valve opening, and the box press presses the valve plate to increase the tightness. The valve plate does not suffer wear as it does not slide over other parts. (Yamaguchi, T.)

  20. Door valve for fuel handling path

    International Nuclear Information System (INIS)

    Makishima, Katsuhiko.

    1969-01-01

    A door valve is provided which seals cover gas from a liquid metal cooled reactor without leakage therefrom. A threaded shaft is screwed into a heavy box press which is packed with lead. The shaft is adapted to be rotated by an electric motor or a manually operated wheel which is disposed outside of the door valve. From the box press a valve plate is suspended by four linkage bars, one for each corner. Each linkage bar is provided with two wheels which are respectively mounted at the connections with the box press and the valve plate. The wheels are carried on the horizontal grooves formed in a door valve casing. In operation the shaft rotates and travels to permit the box press and the valve plate to move into the door valve casing while the valve plate does not contact the casing. When the box press reaches the home position, the wheels drop into the recesses which are disposed at the ends of the grooves, the valve plate is carried on the valve opening, and the box press presses the valve plate to increase the tightness. The valve plate does not suffer wear as it does not over other parts. (Yamaguchi, T.)

  1. Additively Manufactured Main Fuel Valve Housing

    Science.gov (United States)

    Eddleman, David; Richard, Jim

    2015-01-01

    Selective Laser Melting (SLM) was utilized to fabricate a liquid hydrogen valve housing typical of those found in rocket engines and main propulsion systems. The SLM process allowed for a valve geometry that would be difficult, if not impossible to fabricate by traditional means. Several valve bodies were built by different SLM suppliers and assembled with valve internals. The assemblies were then tested with liquid nitrogen and operated as desired. One unit was also burst tested and sectioned for materials analysis. The design, test results, and planned testing are presented herein.

  2. Effect of the sinus of valsalva on the closing motion of bileaflet prosthetic heart valves.

    Science.gov (United States)

    Ohta, Y; Kikuta, Y; Shimooka, T; Mitamura, Y; Yuhta, T; Dohi, T

    2000-04-01

    Conventional bileaflet prosthetic mechanical heart valves close passively with backflow. Naturally, the valve has problems associated with closure, such as backflow, water hammer effect, and fracture of the leaflet. On the other hand, in the case of the natural aortic valve, the vortex flow in the sinus of Valsalva pushes the leaflet to close, and the valve starts the closing motion earlier than the prosthetic valve as the forward flow decelerates. This closing mechanism is thought to decrease backflow at valve closure. In this study, we propose a new bileaflet mechanical valve resembling a drawbridge in shape, and the prototype valve was designed so that the leaflet closes with the help of the vortex flow in the sinus. The test valve was made of aluminum alloy, and its closing motion was compared to that of the CarboMedics (CM) valve. Both valves were driven by a computer controlled hydraulic mock circulator and were photographed at 648 frames/s by a high speed charge-coupled device (CCD) camera. Each frame of the valve motion image was analyzed with a personal computer, and the opening angles were measured. The flow rate was set as 5.0 L/min. The system was pulsed with 70 bpm, and the systolic/diastolic ratio was 0.3. Glycerin water was used as the circulation fluid at room temperature, and polystyrene particles were used to visualize the streamline. The model of the sinus of Valsalva was made of transparent silicone rubber. As a result, high speed video analysis showed that the test valve started the closing motion 41 ms earlier than the CM valve, and streamline analysis showed that the test valve had a closing mechanism similar to the natural one with the effect of vortex flow. The structure of the test valve was thought to be effective for soft closure and could solve problems associated with closure.

  3. Principle and opening-closing character analysis of DC check valve

    International Nuclear Information System (INIS)

    Han Xu; Zhou Yu

    2006-01-01

    When the behaviour of main pump in PWR power plant change, as a result of arresting fluid countercurrent current by check valve, water hammer phenomena met occur more or less in loop. Serious water hammer not only met brought incident of over pressure, imperil pressure boundary, but also may engender check valve lapse. DC check valve is a kind of new theory check valve, is designed to avoid serious water hammer phenomena at tradition check valve closing, the analyses and experiment indicate that DC check valve can availably solve water hammer problem in the loop, and be able to reliably prevent fluid countercurrent. (authors)

  4. Developing an optimal valve closing rule curve for real-time pressure control in pipes

    Energy Technology Data Exchange (ETDEWEB)

    Bazarganlari, Mohammad Reza; Afshar, Hossein [Islamic Azad University, Tehran (Iran, Islamic Republic of); Kerachian, Reza [University of Tehran, Tehran (Iran, Islamic Republic of); Bashiazghadi, Seyyed Nasser [Iran University of Science and Technology, Tehran (Iran, Islamic Republic of)

    2013-01-15

    Sudden valve closure in pipeline systems can cause high pressures that may lead to serious damages. Using an optimal valve closing rule can play an important role in managing extreme pressures in sudden valve closure. In this paper, an optimal closing rule curve is developed using a multi-objective optimization model and Bayesian networks (BNs) for controlling water pressure in valve closure instead of traditional step functions or single linear functions. The method of characteristics is used to simulate transient flow caused by valve closure. Non-dominated sorting genetic algorithms-II is also used to develop a Pareto front among three objectives related to maximum and minimum water pressures, and the amount of water passes through the valve during the valve-closing process. Simulation and optimization processes are usually time-consuming, thus results of the optimization model are used for training the BN. The trained BN is capable of determining optimal real-time closing rules without running costly simulation and optimization models. To demonstrate its efficiency, the proposed methodology is applied to a reservoir-pipe-valve system and the optimal closing rule curve is calculated for the valve. The results of the linear and BN-based valve closure rules show that the latter can significantly reduce the range of variations in water hammer pressures.

  5. Echoguided closed commissurotomy for mitral valve stenosis in a dog.

    Science.gov (United States)

    Trehiou-Sechi, Emilie; Behr, Luc; Chetboul, Valérie; Pouchelon, Jean-Louis; Castaignet, Maud; Gouni, Vassiliki; Misbach, Charlotte; Petit, Amandine M P; Borenstein, Nicolas

    2011-09-01

    Surgical treatment of mitral stenosis (MS) usually consists of open mitral commissurotomy (MC) or percutaneous balloon MC, which require a cardiopulmonary bypass or transseptal approach, respectively. We describe here the first surgical management of congenital MS in a dog using a less invasive procedure, a surgical closed MC under direct echo guidance. A 5-year-old female Cairn terrier was referred for ascites, weakness, and marked exercise intolerance for 2 months, which was refractory to medical treatment. Diagnosis of severe MS associated with atrial fibrillation (AF) was confirmed by echo-Doppler examination and electrocardiography. Poor response to medical treatment suggested a corrective procedure on the valve was indicated. However, due to the cost and high mortality rate associated with cardiopulmonary bypass, a hybrid MC was recommended. A standard left intercostal thoracotomy was performed and three balloon valvuloplasty catheters of differing diameters were sequentially inserted through the left atrium under direct echo guidance. Transesophageal echocardiography revealed a 62% reduction in the pressure half-time compared to the pre-procedure. Thirteen months after surgery the dog is still doing well with resolution of ascites and a marked improvement of most echo-Doppler variables. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. Plug the socket of the main closing valve in a nuclear power plant

    International Nuclear Information System (INIS)

    Neupauer, J.; Bednar, B.

    1988-01-01

    The plug is designed for closing the main closing valve socket during a refuelling shutdown of a nuclear power plant. The plug is fixed in the using jaws forced against the socket ring part. The socket is sealed by expanding a ring between two cone trays. A valve provided in the plug allows draining the pipe. The plug is inserted in the socket using a jib suspended on a rail. Following sealing both sockets the inner surfaces of the closing valve can be decontaminated. Following decontamination, a water-proof cover is slid over the plug protecting the plug moving mechanism from damage. (J.B.). 1 fig

  7. Partially closed fuel cycle of WWER-440

    International Nuclear Information System (INIS)

    Darilek, P.; Sebian, V.; Necas, V.

    2002-01-01

    Position of nuclear energy at the energy sources competition is characterised briefly. Multi-tier transmutation system is outlined out as effective back-end solution and consequently as factor that can increase nuclear energy competitiveness. LWR and equivalent WWER are suggested as a first tier reactors. Partially closed fuel cycle with combined fuel assemblies is briefed. Main back-end effects are characterised (Authors)

  8. Sodium fast reactors with closed fuel cycle

    CERN Document Server

    Raj, Baldev; Vasudeva Rao, PR 0

    2015-01-01

    Sodium Fast Reactors with Closed Fuel Cycle delivers a detailed discussion of an important technology that is being harnessed for commercial energy production in many parts of the world. Presenting the state of the art of sodium-cooled fast reactors with closed fuel cycles, this book:Offers in-depth coverage of reactor physics, materials, design, safety analysis, validations, engineering, construction, and commissioning aspectsFeatures a special chapter on allied sciences to highlight advanced reactor core materials, specialized manufacturing technologies, chemical sensors, in-service inspecti

  9. Two-dimensional FSI simulation of closing dynamics of a tilting disc mechanical heart valve.

    Science.gov (United States)

    Govindarajan, V; Udaykumar, H S; Herbertson, L H; Deutsch, S; Manning, K B; Chandran, K B

    2010-03-01

    The fluid dynamics during valve closure resulting in high shear flows and large residence times of particles has been implicated in platelet activation and thrombus formation in mechanical heart valves. Our previous studies with bi-leaflet valves have shown that large shear stresses induced in the gap between the leaflet edge and the valve housing results in relatively high platelet activation levels whereas flow between the leaflets results in shed vortices not conducive to platelet damage. In this study we compare the result of closing dynamics of a tilting disc valve with that of a bi-leaflet valve. The two-dimensional fluid-structure interaction analysis of a tilting disc valve closure mechanics is performed with a fixed grid Cartesian mesh flow solver with local mesh refinement, and a Lagrangian particle dynamic analysis for computation of potential for platelet activation. Throughout the simulation the flow remains in the laminar regime and the flow through the gap width is marked by the development of a shear layer which separates from the leaflet downstream of the valve. Zones of re-circulation are observed in the gap between the leaflet edge and the valve housing on the major orifice region of the tilting disc valve and are seen to be migrating towards the minor orifice region. Jet flow is observed at the minor orifice region and a vortex is formed which sheds in the direction of fluid motion as observed in experiments using PIV measurements. The activation parameter computed for the tilting disc valve, at the time of closure was found to be 2.7 times greater than that of the bi-leaflet mechanical valve and was found to be in the vicinity of the minor orifice region mainly due to the migration of vortical structures from the major to the minor orifice region during the leaflet rebound of the closing phase.

  10. A numerical insight into elastomer normally closed micro valve actuation with cohesive interfacial cracking modelling

    Science.gov (United States)

    Wang, Dongyang; Ba, Dechun; Hao, Ming; Duan, Qihui; Liu, Kun; Mei, Qi

    2018-05-01

    Pneumatic NC (normally closed) valves are widely used in high density microfluidics systems. To improve actuation reliability, the actuation pressure needs to be reduced. In this work, we utilize 3D FEM (finite element method) modelling to get an insight into the valve actuation process numerically. Specifically, the progressive debonding process at the elastomer interface is simulated with CZM (cohesive zone model) method. To minimize the actuation pressure, the V-shape design has been investigated and compared with a normal straight design. The geometrical effects of valve shape has been elaborated, in terms of valve actuation pressure. Based on our simulated results, we formulate the main concerns for micro valve design and fabrication, which is significant for minimizing actuation pressures and ensuring reliable operation.

  11. Experimental and analytical studies on waterhammer generated by the closing of check valves

    International Nuclear Information System (INIS)

    Huet, J.L.; Garcia, J.L.; Coppolani, P.; Ziegler, B.

    1987-01-01

    A double-guillotine rupture on a water line upstream from a check valve generates a severe transient between the check valve and the pressure vessel on the downstream side. Successively following phenomena occur: - decrease then reversal of the flow, - closing of the check valve with impact of the plug on its seat, - waterhammer propagating in the pipe downstream from the check valve. The COMMISARIAT A L'ENERGIE ATOMIQUE (C.E.A.) FRAMATOME and ELECTRICITE DE FRANCE (E.D.F.) have undertaken a joint program in order to: - investigate the behavior uf the check valve in the event of a sudden closure, - evaluate the pressure and flow transient in the line. The program includes: - full scale tests in two loops, CLAUDIA (C.E.A.) and ECLAIR (E.D.F.), - analytical studies in order to qualify the calculation codes. This paper describes the experimental program and presents the analysis results for a benchmark test

  12. 46 CFR 153.284 - Characteristics of required quick closing valves.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Characteristics of required quick closing valves. 153.284 Section 153.284 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK... and Equipment Piping Systems and Cargo Handling Equipment § 153.284 Characteristics of required quick...

  13. Modeling closed nuclear fuel cycles processes

    Energy Technology Data Exchange (ETDEWEB)

    Shmidt, O.V. [A.A. Bochvar All-Russian Scientific Research Institute for Inorganic Materials, Rogova, 5a street, Moscow, 123098 (Russian Federation); Makeeva, I.R. [Zababakhin All-Russian Scientific Research Institute of Technical Physics, Vasiliev street 13, Snezhinsk, Chelyabinsk region, 456770 (Russian Federation); Liventsov, S.N. [Tomsk Polytechnic University, Tomsk, Lenin Avenue, 30, 634050 (Russian Federation)

    2016-07-01

    Computer models of processes are necessary for determination of optimal operating conditions for closed nuclear fuel cycle (NFC) processes. Computer models can be quickly changed in accordance with new and fresh data from experimental research. 3 kinds of process simulation are necessary. First, the VIZART software package is a balance model development used for calculating the material flow in technological processes. VIZART involves taking into account of equipment capacity, transport lines and storage volumes. Secondly, it is necessary to simulate the physico-chemical processes that are involved in the closure of NFC. The third kind of simulation is the development of software that allows the optimization, diagnostics and control of the processes which implies real-time simulation of product flows on the whole plant or on separate lines of the plant. (A.C.)

  14. Fuzzy Pattern Classification Based Detection of Faulty Electronic Fuel Control (EFC Valves Used in Diesel Engines

    Directory of Open Access Journals (Sweden)

    Umut Tugsal

    2014-05-01

    Full Text Available In this paper, we develop mathematical models of a rotary Electronic Fuel Control (EFC valve used in a Diesel engine based on dynamic performance test data and system identification methodology in order to detect the faulty EFC valves. The model takes into account the dynamics of the electrical and mechanical portions of the EFC valves. A recursive least squares (RLS type system identification methodology has been utilized to determine the transfer functions of the different types of EFC valves that were investigated in this study. Both in frequency domain and time domain methods have been utilized for this purpose. Based on the characteristic patterns exhibited by the EFC valves, a fuzzy logic based pattern classification method was utilized to evaluate the residuals and identify faulty EFC valves from good ones. The developed methodology has been shown to provide robust diagnostics for a wide range of EFC valves.

  15. Performance Evaluation of a High Bandwidth Liquid Fuel Modulation Valve for Active Combustion Control

    Science.gov (United States)

    Saus, Joseph R.; DeLaat, John C.; Chang, Clarence T.; Vrnak, Daniel R.

    2012-01-01

    At the NASA Glenn Research Center, a characterization rig was designed and constructed for the purpose of evaluating high bandwidth liquid fuel modulation devices to determine their suitability for active combustion control research. Incorporated into the rig s design are features that approximate conditions similar to those that would be encountered by a candidate device if it were installed on an actual combustion research rig. The characterized dynamic performance measures obtained through testing in the rig are planned to be accurate indicators of expected performance in an actual combustion testing environment. To evaluate how well the characterization rig predicts fuel modulator dynamic performance, characterization rig data was compared with performance data for a fuel modulator candidate when the candidate was in operation during combustion testing. Specifically, the nominal and off-nominal performance data for a magnetostrictive-actuated proportional fuel modulation valve is described. Valve performance data were collected with the characterization rig configured to emulate two different combustion rig fuel feed systems. Fuel mass flows and pressures, fuel feed line lengths, and fuel injector orifice size was approximated in the characterization rig. Valve performance data were also collected with the valve modulating the fuel into the two combustor rigs. Comparison of the predicted and actual valve performance data show that when the valve is operated near its design condition the characterization rig can appropriately predict the installed performance of the valve. Improvements to the characterization rig and accompanying modeling activities are underway to more accurately predict performance, especially for the devices under development to modulate fuel into the much smaller fuel injectors anticipated in future lean-burning low-emissions aircraft engine combustors.

  16. Real-time numerical evaluation of dynamic tests with sudden closing of valves in piping systems

    International Nuclear Information System (INIS)

    Geidel, W.; Leimbach, K.R.

    1979-01-01

    The sudden closing of a valve in a piping system causes a build-up of pressure which, in turn, causes severe vibrations of the structural system. The licensing procedure calls for on-site tests to determine the dynamic effects of such closing of valves, and to check the stresses and displacements against the allowable ones. The measurements include time histories of displacements, accelerations and internal pressure. The computer program KWUROHR for the static and dynamic analysis of piping systems has been used by KWU and several subcontractors during the past four vears. This program has been extended by adding a subroutine package which computes time histories of displacements, accelerations and stresses resulting from the input of measured time histories of internal pressures at selected locations. The computer algorithm establishes the topological connectivity between the internal pressure measuring locations, to set up a logic for linear pressure interpolation between these points and pressure steps at reducers and valves. A minimum number of input points is required to give realistic results. (orig.)

  17. Effect of vortex generators on the closing transient flow of bileaflet mechanical heart valves

    Science.gov (United States)

    Murphy, David; Dasi, Lakshmi; Yoganathan, Ajit; Glezer, Ari

    2006-11-01

    The time-periodic closing of bileaflet mechanical heart valves is accompanied by a strong flow transient that is associated with the formation of a counter-rotating vortex pair near the b-datum line of leaflet edges. The strong transitory shear that is generated by these vortices may be damaging to blood elements and may result in platelet activation. In the present work, these flow transients are mitigated using miniature vortex generator arrays that are embedded on the surface of the leaflets. Two vortex generator designs were investigated: one design comprised staggered rectangular fins and the other one staggered hemispheres. The closing transients in the absence and presence of the passive vortex generators are characterized using phase locked PIV measurements. The study utilizes a 25 mm St. Jude Medical valve placed in the aortic position of the Georgia Tech left heart simulator. Measurements of the velocity field in the center plane of the leaflets demonstrate that the dynamics of the transient vortices that precede the formation of the leakage jets can be significantly altered and controlled by relatively simple passive modifications of existing valve designs. Human blood experiments validated the effectiveness of miniature vortex generators in reducing thrombus formation by over 42 percent.

  18. Shuttle Primary Reaction Control Subsystem Thruster Fuel Valve Pilot Seal Extrusion: A Failure Correlation

    Science.gov (United States)

    Waller, Jess; Saulsberry, Regor L.

    2003-01-01

    Pilot operated valves (POVs) are used to control the flow of hypergolic propellants monomethylhydrazine (fuel) and nitrogen tetroxide (oxidizer) to the Shuttle orbiter Primary Reaction Control Subsystem (PRCS) thrusters. The POV incorporates a two-stage design: a solenoid-actuated pilot stage, which in turn controls a pressure-actuated main stage. Isolation of propellant supply from the thruster chamber is accomplished in part by a captive polytetrafluoroethylene (PTFE) pilot seal retained inside a Custom 455.1 stainless steel cavity. Extrusion of the pilot seal restricts the flow of fuel around the pilot poppet, thus impeding or preventing the main valve stage from opening. It can also prevent the main stage from staying open with adequate force margin, particularly if there is gas in the main stage actuation cavity. During thruster operation on-orbit, fuel valve pilot seal extrusion is commonly indicated by low or erratic chamber pressure or failure of the thruster to fire upon command (Fail-Off). During ground turnaround, pilot seal extrusion is commonly indicated by slow gaseous nitrogen (GN2) main valve opening times (greater than 38 ms) or slow water main valve opening response times (greater than 33 ms). Poppet lift tests and visual inspection can also detect pilot seal extrusion during ground servicing; however, direct metrology on the pilot seat assembly provides the most quantitative and accurate means of identifying extrusion. Minimizing PRCS fuel valve pilot seal extrusion has become an important issue in the effort to improve PRCS reliability and reduce associated life cycle costs.

  19. Spent fuel management and closed nuclear fuel cycle

    International Nuclear Information System (INIS)

    Kudryavtsev, E.G.

    2012-01-01

    Strategic objectives set by Rosatom Corporation in the field of spent fuel management are given. By 2030, Russia is to create technological infrastructure for innovative nuclear energy development, including complete closure of the nuclear fuel cycle. A target model of the spent NPP nuclear fuel management system until 2030 is analyzed. The schedule for key stages of putting in place the infrastructure for spent NPP fuel management is given. The financial aspect of the problem is also discussed [ru

  20. High Temperature, High Frequency Fuel Metering Valve, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Active Signal Technologies and its subcontractor Moog propose to develop a high-frequency actuator driven valve intended to achieve TRL 6 by the end of Phase II....

  1. Closed Fuel Cycle Waste Treatment Strategy

    Energy Technology Data Exchange (ETDEWEB)

    Vienna, J. D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Collins, E. D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Crum, J. V. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Ebert, W. L. [Argonne National Lab. (ANL), Argonne, IL (United States); Frank, S. M. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Garn, T. G. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Gombert, D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Jones, R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Jubin, R. T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Maio, V. C. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Marra, J. C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Matyas, J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Nenoff, T. M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Riley, B. J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Sevigny, G. J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Soelberg, N. R. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Strachan, D. M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Thallapally, P. K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Westsik, J. H. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-02-01

    This study is aimed at evaluating the existing waste management approaches for nuclear fuel cycle facilities in comparison to the objectives of implementing an advanced fuel cycle in the U.S. under current legal, regulatory, and logistical constructs. The study begins with the Global Nuclear Energy Partnership (GNEP) Integrated Waste Management Strategy (IWMS) (Gombert et al. 2008) as a general strategy and associated Waste Treatment Baseline Study (WTBS) (Gombert et al. 2007). The tenets of the IWMS are equally valid to the current waste management study. However, the flowsheet details have changed significantly from those considered under GNEP. In addition, significant additional waste management technology development has occurred since the GNEP waste management studies were performed. This study updates the information found in the WTBS, summarizes the results of more recent technology development efforts, and describes waste management approaches as they apply to a representative full recycle reprocessing flowsheet. Many of the waste management technologies discussed also apply to other potential flowsheets that involve reprocessing. These applications are occasionally discussed where the data are more readily available. The report summarizes the waste arising from aqueous reprocessing of a typical light-water reactor (LWR) fuel to separate actinides for use in fabricating metal sodium fast reactor (SFR) fuel and from electrochemical reprocessing of the metal SFR fuel to separate actinides for recycle back into the SFR in the form of metal fuel. The primary streams considered and the recommended waste forms include; Tritium in low-water cement in high integrity containers (HICs); Iodine-129: As a reference case, a glass composite material (GCM) formed by the encapsulation of the silver Mordenite (AgZ) getter material in a low-temperature glass is assumed. A number of alternatives with distinct advantages are also considered including a fused silica waste form

  2. Effects of cooling time on a closed LWR fuel cycle

    International Nuclear Information System (INIS)

    Arnold, R. P.; Forsberg, C. W.; Shwageraus, E.

    2012-01-01

    In this study, the effects of cooling time prior to reprocessing spent LWR fuel has on the reactor physics characteristics of a PWR fully loaded with homogeneously mixed U-Pu or U-TRU oxide (MOX) fuel is examined. A reactor physics analysis was completed using the CASM04e code. A void reactivity feedback coefficient analysis was also completed for an infinite lattice of fresh fuel assemblies. Some useful conclusions can be made regarding the effect that cooling time prior to reprocessing spent LWR fuel has on a closed homogeneous MOX fuel cycle. The computational analysis shows that it is more neutronically efficient to reprocess cooled spent fuel into homogeneous MOX fuel rods earlier rather than later as the fissile fuel content decreases with time. Also, the number of spent fuel rods needed to fabricate one MOX fuel rod increases as cooling time increases. In the case of TRU MOX fuel, with time, there is an economic tradeoff between fuel handling difficulty and higher throughput of fuel to be reprocessed. The void coefficient analysis shows that the void coefficient becomes progressively more restrictive on fuel Pu content with increasing spent fuel cooling time before reprocessing. (authors)

  3. Thermal performance of horizontal closed-loop oscillating heat-pipe with check valves

    International Nuclear Information System (INIS)

    Rittidech, S.; Pipatpaiboon, N.; Thongdaeng, S.

    2010-01-01

    This research investigated the thermal performance of various horizontal closed-loop oscillating heat-pipe systems with check valves (HCLOHPs/CVs). Numerous test systems were constructed using copper capillary tubes with assorted inner diameters, evaporator lengths, and check valves. The test systems were evaluated under normal operating conditions using ethanol, R123, and distilled water as working fluids. The system's evaporator sections were heated by hot water from a hot bath, and the heat was removed from the condenser sections by cold water from a cool bath. The adiabatic sections were well insulated with foam insulators. The heat-transfer performance of the various systems was evaluated in terms of the rate of heat transferred to the cold water at the condenser. The results showed that the heat-transfer performance of an HCLOHP/CV system could be improved by decreasing the evaporator length. The highest performance of all tested systems was obtained when the maximum number of system check valves was 2. The maximum heat flux occurred with a 2 mm inner diameter tube, and R123 was determined to be the most suitable working fluid

  4. Characteristics of fast reactor core designs and closed fuel cycle

    International Nuclear Information System (INIS)

    Poplavsky, V.M.; Eliseev, V.A.; Matveev, V.I.; Khomyakov, Y.S.; Tsyboulya, A.M.; Tsykunov, A.G.; Chebeskov, A.N.

    2007-01-01

    On the basis of the results of recent studies, preliminary basic requirements related to characteristics of fast reactor core and nuclear fuel cycle were elaborated. Decreasing reactivity margin due to approaching breeding ratio to 1, requirements to support non-proliferation of nuclear weapons, and requirements to decrease amount of radioactive waste are under consideration. Several designs of the BN-800 reactor core have been studied. In the case of MOX fuel it is possible to reach a breeding ratio about 1 due to the use of larger size of fuel elements with higher fuel density. Keeping low axial fertile blanket that would be reprocessed altogether with the core, it is possible to set up closed fuel cycle with the use of own produced plutonium only. Conceptual core designs of advanced commercial reactor BN-1800 with MOX and nitride fuel are also under consideration. It has been shown that it is expedient to use single enrichment fuel core design in this reactor in order to reach sufficient flattening and stability of power rating in the core. The main feature of fast reactor fuel cycle is a possibility to utilize plutonium and minor actinides which are the main contributors to the long-living radiotoxicity in irradiated nuclear fuel. The results of comparative analytical studies on the risk of plutonium proliferation in case of open and closed fuel cycle of nuclear power are also presented in the paper. (authors)

  5. Closing the nuclear fuel cycle: the impact of indecision

    International Nuclear Information System (INIS)

    Schubert, A.E.

    1976-01-01

    The supply-demand reprocessing capacity problem caused by failure to close the ''back end'' of the fuel cycle is discussed. An economic study was conducted by Allied-General of the effects of ''throwaway'' fuel cycle; results show that the reprocessing alternative with U and Pu recycle is clearly superior economically to the ''throwaway'' alternative, with a net benefit of $10 million per year per reactor. Obstacles to private enterprise in reprocessing and recycle are next considered, and some possible solutions to delays in closing the ''back end'' of the fuel cycle are discussed

  6. Analysis of Water Hammer with Different Closing Valve Laws on Transient Flow of Hydrogen-Natural Gas Mixture

    Directory of Open Access Journals (Sweden)

    Norazlina Subani

    2015-01-01

    Full Text Available Water hammer on transient flow of hydrogen-natural gas mixture in a horizontal pipeline is analysed to determine the relationship between pressure waves and different modes of closing and opening of valves. Four types of laws applicable to closing valve, namely, instantaneous, linear, concave, and convex laws, are considered. These closure laws describe the speed variation of the hydrogen-natural gas mixture as the valve is closing. The numerical solution is obtained using the reduced order modelling technique. The results show that changes in the pressure wave profile and amplitude depend on the type of closing laws, valve closure times, and the number of polygonal segments in the closing function. The pressure wave profile varies from square to triangular and trapezoidal shape depending on the type of closing laws, while the amplitude of pressure waves reduces as the closing time is reduced and the numbers of polygonal segments are increased. The instantaneous and convex closing laws give rise to minimum and maximum pressure, respectively.

  7. LWRA analysis of inadvertent closing of the main steam isolation valve in NPP Krsko

    International Nuclear Information System (INIS)

    Feretic, D.; Cavlina, N.; Grgic, D.; Spalj, S.

    1996-01-01

    The paper describes the use of system code RELAP5/mod2 and analyzer code LWRA in analysis of inadvertent closing of the main steam isolation valve that happened in NPP Krsko on September, 25 1995. Three cases were calculated in order to address different aspects of the modelled transient. This preliminary calculation showed that, even though the real plant behaviour was not completely reproduced, such kind of analysis can help to better understand plant behaviour and to identify important phenomena in the plant during transient. The results calculated by RELAP5 and LWRA were similar and both codes indicated lack of better understanding of the plant systems status. The LWRA was more than 5 times faster than real time. (author)

  8. New Concept of Designing Composite Fuel for Fast Reactors with Closing Fuel Cycle

    International Nuclear Information System (INIS)

    Savchenko, A.; Vatulin, A.; Uferov, O.; Kulakov, G.; Sorokin, V.

    2013-01-01

    For fast reactors a novel type of promising composite U-PuO2 fuel is proposed which is based on dispersion fuel elements. Basic approach to fuel element development - separated operations of fabricating uranium meat fuel element and introducing into it Pu or MA dioxides powder, that results in minimizing dust forming operations in fuel element fabrication. Novel fuel features higher characteristics in comparison to metallic or MOX fuel its fabrication technology is readily accomplished and is environmentally clean. A possibility is demonstrated of fabricating coated steel claddings to protect from interaction with fuel and fission products when use standard rod type MOX or metallic U-Pu-Zr fuel. Novel approach to reprocessing of composite fuel is demonstrated, which allows to separate uranium from burnt plutonium as well as the newly generated fissile plutonium from burnt one without chemical processes, which simplifies the closing of the nuclear fuel cycle. Novel composite fuel combines the advantages of metallic and ceramic types of fuel and has high uranium density that allows also to implicate it in BREST types reactor with conversion ratio more than 1. Peculiarities of closing nuclear cycle with composite fuel are demonstrated that allows more effective re-usage of generated Pu as well as, minimizing r/a wastes by incineration of MA in specially developed IMF design

  9. Closing the fuel cycle: A superior option for India

    International Nuclear Information System (INIS)

    Balu, K.; Purushotham, D.S.C.; Kakodkar, A.

    1999-01-01

    The closed fuel cycle option with reprocessing and recycle of uranium and plutonium (U and Pu) for power generation allows better utilization of the uranium resources. On its part, plutonium is a unique energy source. During the initial years of nuclear fuel cycle activities, reprocessing and recycle of uranium and plutonium for power generation was perceived by many countries to be among the best of long term strategies for the management of spent fuel. But, over the years, some of the countries have taken a position that once-through fuel cycle is both economical and proliferation-resistant. However, such perceptions do vary as a function of economic growth and energy security of a given country. This paper deals with techno-economic perspectives of reprocessing and recycling in the Indian nuclear power programme. Experience of developing Mixed Oxide UO 2 -PuO 2 (MOX) fuel and its actual use in a power reactor (BWR) is presented. The paper further deals with the use of MOX in PHWRs in the future and current thinking, in the Indian context, in respect of advanced fuel cycles for the future. From environmental safety considerations, the separation of long-lived isotopes and minor actinides from high level waste (HLW) would enhance the acceptability of reprocessing and recycle option. The separated actinides are suitable for recycling with MOX fuel. However, the advanced fuel cycles with such recycling of Uranium and transuranium elements call for additional sophisticated fuel cycle activities which are yet to be mastered. India is interested in both uranium and thorium fuel cycles. This paper describes the current status of the Indian nuclear power scenario with reference to the program on reactors, reprocessing and radioactive waste management, plutonium recycle options, thorium-U233 fuel cycle studies and investigations on partitioning of actinides from Purex HLW as relevant to PHWR spent fuels. (author)

  10. Closed-bore XMR (CBXMR) systems for aortic valve replacement: X-ray tube imaging performance

    International Nuclear Information System (INIS)

    Bracken, John A.; Komljenovic, Philip; Lillaney, Prasheel V.; Fahrig, Rebecca; Rowlands, J. A.

    2009-01-01

    A hybrid closed-bore x-ray/MRI system (CBXMR) is proposed to improve the safety and efficacy of percutaneous aortic valve replacement procedures. In this system, an x-ray C-arm will be positioned about 1 m from the entrance of a 1.5 T MRI scanner. The CBXMR system will harness the complementary strengths of both modalities to guide and deploy a bioprosthetic valve into the aortic annulus of the heart without coronary artery obstruction. A major challenge in constructing this system is ensuring proper operation of a rotating-anode x-ray tube in the MRI magnetic fringe field environment. The electron beam in the x-ray tube responsible for producing x rays can be deflected by the fringe field. However, the clinical impact of electron beam deflection in a magnetic field has not yet been studied. Here, the authors investigated changes in focal spot resolving power, field of view shift, and field of view truncation in x-ray images as a result of electron beam deflection. The authors found that in the fringe field acting on the x-ray tube at the clinical location for the x-ray C-arm (4 mT), focal spot size increased by only 2%, so the fringe field did not limit the resolving power of the x-ray system. The magnetic field also caused the field of view to shift by 3 mm. This shift must be corrected to avoid unnecessary primary radiation exposure to the patient and the staff in the cardiac catheterization laboratory. The fringe field was too weak to cause field of view truncation.

  11. The Otto-Atkinson engine. A study of fluid flow and combustion with early and late inlet valve closing

    Energy Technology Data Exchange (ETDEWEB)

    Haakansson, Henrik

    1999-10-01

    This report contains results of measurements on an Otto engine. The purpose for this work has been to do measurements of the flow in the cylinder but also measurements of the cylinder pressure have been performed. The flow measurements are made with the method Laser Doppler Velocimetry, LDV. The reason why these measurements are made at all are the pump losses that implies a lower efficiency for the Otto engine at part load. In this work two alternative ways that highly reduces the pump losses are examined. These are early inlet valve closing and late inlet valve closing. To further increase the efficiency at part load an increased compression ratio has been used together with the different valve strategies. With these two ways of operation, at a part load of about 4 - 5 IMEP{sub net}, increases of about 20% of the net indicated efficiency has been obtained. Additionally this report contains a chapter about the possible use of a variable valve actuation or timing system, VVA or VVT. Many conditions for the Otto cycle can be improved by the use of a variable valve actuation and in this chapter it is dealt with the most important ones.

  12. Automated Temperature Control with Adjusting Outlet Valve of Fuel in the Process of Cooking Palm Sugar

    Science.gov (United States)

    Aripin, H.; Hiron, Nurul; Priatna, Edvin; Busaeri, Nundang; Andang, Asep; Suhartono; Sabchevski, Svilen

    2018-04-01

    In this paper, a real-time temperature control system for coconut sugar cooking is presented. It is based on a thermocouple temperature sensor. The temperature in the closed evaporator is used as a control variable of the DC servo control system for opening and closing of a valve embedded in a gas burner. The output power level, which is necessary in order to reach the target temperature is controlled by the microcontroller ATMega328P. A circuit module for control of the valve and temperature sensors as well as software for data acquisition have been implemented. The test results show that the system properly stabilizes the temperature in the closed evaporator for coconut sugar cooking in the range from room temperature to 110°C. A set point can be reached and held with an accuracy of ±0.75°C at a temperature of 110°C for 60 minutes.

  13. A statistical analysis on failure-to open/close probability of pneumatic valve in sodium cooling systems

    International Nuclear Information System (INIS)

    Kurisaka, Kenichi

    1999-11-01

    The objective of this study is to develop fundamental data for examination on efficiency of preventive maintenance and surveillance test from the standpoint of failure probability. In this study, as a major standby component, a pneumatic valve in sodium cooling systems was selected. A statistical analysis was made about a trend of valve in sodium cooling systems was selected. A statistical analysis was made about a trend of valve failure-to-open/close (FTOC) probability depending on number of demands ('n'), time since installation ('t') and standby time since last open/close action ('T'). The analysis is based on the field data of operating- and failure-experiences stored in the Component Reliability Database and Statistical Analysis System for LMFBR's (CORDS). In the analysis, the FTOC probability ('P') was expressed as follows: P=1-exp{-C-En-F/n-λT-aT(t-T/2)-AT 2 /2}. The functional parameters, 'C', 'E', 'F', 'λ', 'a' and 'A', were estimated with the maximum likelihood estimation method. As a result, the FTOC probability is almost expressed with the failure probability being derived from the failure rate under assumption of the Poisson distribution only when valve cycle (i.e. open-close-open cycle) exceeds about 100 days. When the valve cycle is shorter than about 100 days, the FTOC probability can be adequately estimated with the parameter model proposed in this study. The results obtained from this study may make it possible to derive an adequate frequency of surveillance test for a given target of the FTOC probability. (author)

  14. Gas release from pressurized closed pores in nuclear fuels

    International Nuclear Information System (INIS)

    Bailey, P.; Donnelly, S.E.; Armour, D.G.; Matzke, H.

    1988-01-01

    Gas release from the nuclear fuels UO 2 and UN out of pressurized closed pores produced by autoclave anneals has been studied by Thermal Desorption Spectrometry (TDS). Investigation of gas release during heating and cooling has indicated stress related mechanical effects leading to gas release. This release occurred in a narrow temperature range between about 1000 and 1500 K for UO 2 , but it continued down to ambient temperature for UN. No burst release was observed above 1500 K for UO 2 . (orig.)

  15. Statistical analysis on failure-to-open/close probability of motor-operated valve in sodium system

    International Nuclear Information System (INIS)

    Kurisaka, Kenichi

    1998-08-01

    The objective of this work is to develop basic data for examination on efficiency of preventive maintenance and actuation test from the standpoint of failure probability. This work consists of a statistical trend analysis of valve failure probability in a failure-to-open/close mode on time since installation and time since last open/close action, based on the field data of operating- and failure-experience. In this work, the terms both dependent and independent on time were considered in the failure probability. The linear aging model was modified and applied to the first term. In this model there are two terms with both failure rates in proportion to time since installation and to time since last open/close-demand. Because of sufficient statistical population, motor-operated valves (MOV's) in sodium system were selected to be analyzed from the CORDS database which contains operating data and failure data of components in the fast reactors and sodium test facilities. According to these data, the functional parameters were statistically estimated to quantify the valve failure probability in a failure-to-open/close mode, with consideration of uncertainty. (J.P.N.)

  16. Analytical solution and numerical study on water hammer in a pipeline closed with an elastically attached valve

    Science.gov (United States)

    Henclik, Sławomir

    2018-03-01

    The influence of dynamic fluid-structure interaction (FSI) onto the course of water hammer (WH) can be significant in non-rigid pipeline systems. The essence of this effect is the dynamic transfer of liquid energy to the pipeline structure and back, which is important for elastic structures and can be negligible for rigid ones. In the paper a special model of such behavior is analyzed. A straight pipeline with a steady flow, fixed to the floor with several rigid supports is assumed. The transient is generated by a quickly closed valve installed at the end of the pipeline. FSI effects are assumed to be present mainly at the valve which is fixed with a spring dash-pot attachment. Analysis of WH runs, especially transient pressure changes, for various stiffness and damping parameters of the spring dash-pot valve attachment is presented in the paper. The solutions are found analytically and numerically. Numerical results have been computed with the use of an own computer program developed on the basis of the four equation model of WH-FSI and the specific boundary conditions formulated at the valve. Analytical solutions have been found with the separation of variables method for slightly simplified assumptions. Damping at the dash-pot is taken into account within the numerical study. The influence of valve attachment parameters onto the WH courses was discovered and it was found the transient amplitudes can be reduced. Such a system, elastically attached shut-off valve in a pipeline or other, equivalent design can be a real solution applicable in practice.

  17. Use of the disruption mitigation valve in closed loop for routine protection at JET

    International Nuclear Information System (INIS)

    Reux, Cédric; Lehnen, Michael; Kruezi, Uron; Jachmich, Stefan; Card, Peter; Heinola, Kalle; Joffrin, Emmanuel; Lomas, Peter J.; Marsen, Stefan; Matthews, Guy; Riccardo, Valeria; Rimini, Fernanda; Vries, Peter de

    2013-01-01

    Highlights: ► A massive gas injection valve was used for disruption routine mitigation at JET. ► A disruption mitigation valve was integrated in JET real time systems. ► Simple triggering schemes such as mode lock were used for disruption detection. ► High forces disruptions were prevented by the use of the gas valve. ► Radiated energy is higher in mitigated disruption than in unmitigated ones. -- Abstract: Disruptions are a major concern for next-generation tokamaks, including ITER. Heat loads, electromagnetic forces and runaway electrons generated by disruptions have to be mitigated for a reliable operation of future machines. Massive gas injection is one of the methods proposed for disruption mitigation. This article reports the first use of massive gas injection as an active disruption protection system at JET. During the 2011–2012 campaigns, 67 disruptions have been mitigated by the disruption mitigation valve (DMV) following a detection by mode lock amplitude and loop voltage changes. Most of disruptions where the valve was intended to be used were successfully mitigated by the DMV, although at different stages of the typical slow disruptions of the ITER-like wall. The fraction of magnetic and thermal energy radiated during the disruption was found to be increased by the action of the DMV. Vertical forces dispersion was also reduced. No non-sustained breakdown was observed following pulses terminated by the disruption mitigation valve

  18. Use of the disruption mitigation valve in closed loop for routine protection at JET

    Energy Technology Data Exchange (ETDEWEB)

    Reux, Cédric, E-mail: cedric.reux@ccfe.ac.uk [Ecole Polytechnique, LPP, CNRS UMR 7648, 91128 Palaiseau (France); JET-EFDA, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Lehnen, Michael; Kruezi, Uron [Association EURATOM-FZJ, Trilateral Euregio Cluster, 52425 Julich (Germany); Jachmich, Stefan [Laboratoire de Physique des Plasmas-Laboratorium voor Plasmafysica, Association EURATOM-Belgian State Institute ERM/KMS, B-1000 Brussels (Belgium); EFDA-CSU, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Card, Peter [Culham Science Centre, EURATOM/CCFE Association, Abingdon OX14 3DB (United Kingdom); Heinola, Kalle [Department of Physics, University of Helsinki, P.O. Box 64, 00014 University of Helsinki (Finland); Joffrin, Emmanuel [CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France); Lomas, Peter J. [Culham Science Centre, EURATOM/CCFE Association, Abingdon OX14 3DB (United Kingdom); Marsen, Stefan [Max-Planck-Institut für Plasmaphysik, Teilinstitut Greifswald, EURATOM-Assoziation, D-17491 Greifswald (Germany); Matthews, Guy; Riccardo, Valeria; Rimini, Fernanda [Culham Science Centre, EURATOM/CCFE Association, Abingdon OX14 3DB (United Kingdom); Vries, Peter de [FOM Institute DIFFER, P.O. Box 1207, 3430 BE Nieuwegein (Netherlands)

    2013-10-15

    Highlights: ► A massive gas injection valve was used for disruption routine mitigation at JET. ► A disruption mitigation valve was integrated in JET real time systems. ► Simple triggering schemes such as mode lock were used for disruption detection. ► High forces disruptions were prevented by the use of the gas valve. ► Radiated energy is higher in mitigated disruption than in unmitigated ones. -- Abstract: Disruptions are a major concern for next-generation tokamaks, including ITER. Heat loads, electromagnetic forces and runaway electrons generated by disruptions have to be mitigated for a reliable operation of future machines. Massive gas injection is one of the methods proposed for disruption mitigation. This article reports the first use of massive gas injection as an active disruption protection system at JET. During the 2011–2012 campaigns, 67 disruptions have been mitigated by the disruption mitigation valve (DMV) following a detection by mode lock amplitude and loop voltage changes. Most of disruptions where the valve was intended to be used were successfully mitigated by the DMV, although at different stages of the typical slow disruptions of the ITER-like wall. The fraction of magnetic and thermal energy radiated during the disruption was found to be increased by the action of the DMV. Vertical forces dispersion was also reduced. No non-sustained breakdown was observed following pulses terminated by the disruption mitigation valve.

  19. Alterations of valve closing behavior in juvenile Catarina scallops (Argopecten ventricosus Sowerby, 1842) exposed to toxic metals.

    Science.gov (United States)

    Sobrino-Figueroa, A; Cáceres-Martínez, C

    2009-11-01

    We conducted an evaluation of alterations produced in the valve closing speed of juvenile Argopecten ventricosus (Catarina scallop) exposed to the metals cadmium, chromium and lead, because of the connection of this response to the state of health of the mollusk. Bioassays were conducted with 50 juveniles (length 3 +/- 0.5 cm) exposed to 0.02, 0.1, 0.2 mg Cd l(-1); 0.1, 0.5, 1.0 mg Cr l(-1); 0.04, 0.2, 0.4 mg Pb l(-1) and 0.8 and 1.6 mg Cd + Cr + Pb l(-1) for 480 h. The average valve closing speed at the end of the experiment was under 1 s in the control group, from 2 to 3.6 s in the bioassays with cadmium, from 1.4 to 3.4 s with chromium, from 3 to 12 s with lead, and from 12 to 15 s with the metal mixtures. It was found that there are significant differences between the values recorded in assays with metals and the control (P < 0.05). The retardation of valve closing in the organisms exposed to toxic substances is probably caused by damage to the sensory cilia located on the edge of the mantle.

  20. Determination of equilibrium fuel composition for fast reactor in closed fuel cycle

    Directory of Open Access Journals (Sweden)

    Ternovykha Mikhail

    2017-01-01

    Full Text Available Technique of evaluation of multiplying and reactivity characteristics of fast reactor operating in the mode of multiple refueling is presented. We describe the calculation model of the vertical section of the reactor. Calculation validations of the possibility of correct application of methods and models are given. Results on the isotopic composition, mass feed, and changes in the reactivity of the reactor in closed fuel cycle are obtained. Recommendations for choosing perspective fuel compositions for further research are proposed.

  1. Optimization experiment of gas oil direct injection valve for CNG dual fuel diesel engine

    Energy Technology Data Exchange (ETDEWEB)

    Kim, B.Y. [Chonnam National University Graduate School, Jeonju (Korea); Park, C. K. [Chonnam National University, Jeonju (Korea)

    1999-04-01

    In this study, we studied for a conversion from diesel engine to natural gas dual fuel engine. For this experimental, we tested about the injection quantity characteristics of pilot valve with the plunger diameter at the retraction volume and investigated to the engine performance and exhaust emissions with the nozzle hole number and injection nozzle diameter. As a result, when the plunger diameter is 7.5 mm at the retraction volume, 25 mm{sup 3}/st, the injection quantity characteristics develop. Also, when a nozzle type is 4*{phi} 0.24, total hydrocarbon(THC) emission reduce at low equivalence ratio. (author). 5 refs., 10 figs., 2 tabs.

  2. Closing nuclear fuel cycle with fast reactors: problems and prospects

    Energy Technology Data Exchange (ETDEWEB)

    Shadrin, A.; Dvoeglazov, K.; Ivanov, V. [Bochvar Institute - VNIINM, Moscow (Russian Federation)

    2013-07-01

    The closed nuclear fuel cycle (CNFC) with fast reactors (FR) is the most promising way of nuclear energetics development because it prevents spent nuclear fuel (SNF) accumulation and minimizes radwaste volume due to minor actinides (MA) transmutation. CNFC with FR requires the elaboration of safety, environmentally acceptable and economically effective methods of treatment of SNF with high burn-up and low cooling time. The up-to-date industrially implemented SNF reprocessing technologies based on hydrometallurgical methods are not suitable for the reprocessing of SNF with high burn-up and low cooling time. The alternative dry methods (such as electrorefining in molten salts or fluoride technologies) applicable for such SNF reprocessing have not found implementation at industrial scale. So the cost of SNF reprocessing by means of dry technologies can hardly be estimated. Another problem of dry technologies is the recovery of fissionable materials pure enough for dense fuel fabrication. A combination of technical solutions performed with hydrometallurgical and dry technologies (pyro-technology) is proposed and it appears to be a promising way for the elaboration of economically, ecologically and socially accepted technology of FR SNF management. This paper deals with discussion of main principle of dry and aqueous operations combination that probably would provide safety and economic efficiency of the FR SNF reprocessing. (authors)

  3. Multiple recycle of REMIX fuel at VVER-1000 operation in closed fuel cycle

    Energy Technology Data Exchange (ETDEWEB)

    Alekseev, P. N.; Bobrov, E. A., E-mail: evgeniybobrov89@rambler.ru; Chibinyaev, A. V.; Teplov, P. S.; Dudnikov, A. A. [National Research Center Kurchatov Institute (Russian Federation)

    2015-12-15

    The basic features of loading the VVER-1000 core with a new variant of REMIX fuel (REgenerated MIXture of U–Pu oxides) are considered during its multiple recycle in a closed nuclear fuel cycle. The fuel composition is produced on the basis of the uranium–plutonium regenerate extracted at processing the spent nuclear fuel (SNF) from a VVER-1000, depleted uranium, and the fissionable material: {sup 235}U as a part of highly enriched uranium (HEU) from warheads superfluous for defense purposes or {sup 233}U accumulated in thorium blankets of fusion (electronuclear) neutron sources or fast reactors. Production of such a fuel assumes no use of natural uranium in addition. When converting a part of the VVER-1000 reactors to the closed fuel cycle based on the REMIX technology, the consumption of natural uranium decreases considerably, and there is no substantial degradation of the isotopic composition of plutonium or change in the reactor-safety characteristics at the passage from recycle to recycle.

  4. The Use of Large Valve Overlap in Scavenging a Supercharged Spark-ignition Engine Using Fuel Injection

    Science.gov (United States)

    Schey, Oscar W; Young, Alfred W

    1932-01-01

    This investigation was conducted to determine the effect of more complete scavenging on the full throttle power and the fuel consumption of a four-stroke-cycle engine. The NACA single-cylinder universal test engine equipped with both a fuel-injection system and a carburetor was used. The engine was scavenged by using a large valve overlap and maintaining a pressure in the inlet manifold of 2 inches of mercury above atmospheric. The maximum valve overlap used was 112 degrees. Tests were conducted for a range of compression ratios from 5.5 to 8.5. Except for variable speed tests, all tests were conducted at an engine speed of 1,500 r.p.m. The results of the tests show that the clearance volume of an engine can be scavenged by using a large valve overlap and about 2 to 5 inches of mercury pressure difference between the inlet and exhaust valve. With a fuel-injection system when the clearance volume was scavenged, a b.m.e.p. of over 185 pounds per square inch and a fuel consumption of 9.45 pound per brake horsepower per hour were obtained with a 6.5 compression ratio. An increase of approximately 10 pounds per square inch b.m.e.p. was obtained with a fuel-injection system over that with a carburetor.

  5. Biomass fueled closed cycle gas turbine with water injection

    Energy Technology Data Exchange (ETDEWEB)

    Bardi, Silvia [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Chemical Engineering and Technology

    2001-01-01

    Direct water injection has been studied for a small scale ({approx} 8 MW fuel input) closed cycle gas turbine coupled to a biomass fueled CFB furnace. Two different working fluids have been considered (helium-water mixture and nitrogen-water mixture). The water injection could take place between the compressor stages, as an intercooler, or after the high pressure compressor, as an aftercooler. Both this options have been studied, varying the relative humidity levels after the injection and the temperatures of the injected water. The effect of water injection on thermodynamic properties of the working fluids has been studied, together with its effect on turbomachinery isentropic efficiency. A sensitivity analysis on turbomachinery efficiency and cycle base pressure has been included. The results from this study have been compared to the performance of a dry closed cycle without water injection. The wet cycle shows an electric efficiency in the range 29-32% with helium-water mixture as working fluid and 30-32% with nitrogen-water mixture as working fluid, while the total efficiency (referring to the fuel LHV) is always higher than 100%. In the non-injected cycle the electric efficiency is 30-35% with helium and 32-36 with nitrogen. The total efficiency in the dry case with two level intercooling and postcooling is 87-89%, while is higher than 100% when only one stage inter- and postcooling is present. Aside from this, the study also includes a sizing of the heat exchangers for the different cycle variations. The heat transfer area is very sensible to the working fluid and to the amount of injected water and it's always higher when a nitrogen-water mixture is used. Compared to the cycle without water injection, by the way, the number of heat exchangers is reduced. This will lead to a lower pressure drop and a simpler plant layout. The total heat transfer area, however, is higher in the wet cycle than in the dry cycle.

  6. CFD simulation of flow-pressure characteristics of a pressure control valve for automotive fuel supply system

    International Nuclear Information System (INIS)

    Wu, Dazhuan; Li, Shiyang; Wu, Peng

    2015-01-01

    Highlights: • Direct CFD method for flow-pressure characteristic of a pressure control valve. • Fitted and interpreted the constants of the spool hydraulic force equation. • Established a flow coefficient function of both valve opening and pressure drop. • Developed an indirect CFD method based on the valve-governing equations. - Abstract: This study aims to elaborate on specific computational fluid dynamics (CFD) simulation methods for fitting the flow-pressure curve of a pressure control valve, which is spring-load valve widely used in the automotive fuel supply system. Given that the couple mechanism exists between the flow field in the valve and the spring system, numerous researchers chose to fit the characteristic curve with experimental approaches but scarcely focused on CFD methods. A direct CFD method is introduced in this study to solve this problem. Two evaluation criteria are used to determine whether the internal flow is physically real. An experiment is conducted to verify the simulation results, and the accuracy of this CFD method is proved. However, it is designed to solve one operating condition with fixed spring parameters and the accuracy depends on the amount of operating conditions. Thus, an indirect CFD method is developed based on the well-elaborated valve-governing equations to improve the efficiency and broaden the application extension. This method aims to simulate the exact value of the equation constants to uncouple the flow by numerical method. It is capable of dealing with changed operating conditions and varied spring parameters, and the results are also verified. The visualization of the internal flow provides a better understanding of the flow fields in the valve. The valve gap directly influences the hydraulic force distribution on the spool and causes most pressure loss. The physical meaning of the function constants are explained based on the flow analysis

  7. Liquid air fueled open–closed cycle Stirling engine

    International Nuclear Information System (INIS)

    Xu, Weiqing; Wang, Jia; Cai, Maolin; Shi, Yan

    2015-01-01

    Highlights: • Energy of liquid air is divided into cryogenic energy and expansion energy. • Open–closed cycle Stirling mechanism is employed to improve efficiency. • The Schmidt theory is modified to describe temperature variation in cold space. - Abstract: An unconventional Stirling engine is proposed and its theoretical analysis is performed. The engine belongs to a “cryogenic heat engine” that is fueled by cryogenic medium. Conventional “cryogenic heat engine” employs liquid air as pressure source, but disregards its heat-absorbing ability. Therefore, its efficiency can only be improved by increasing vapor pressure, accordingly increasing the demand on pressure resistance and sealing. In the proposed engine, the added Stirling mechanism helps achieve its high efficiency and simplicity by utilizing the heat-absorbing ability of liquid air. On one hand, based on Stirling mechanism, gas in the hot space absorbs heat from atmosphere when expanding; gas in the cold space is cooled down by liquid air when compressed. Taking atmosphere as heat source and liquid air as heat sink, a closed Stirling cycle is formed. On the other hand, an exhaust port is set in the hot space. When expanding in the hot space, the vaporized gas is discharged through the exhaust port. Thus, an open cycle is established. To model and analyze the system, the Schmidt theory is modified to describe temperature variation in the cold space, and irreversible characteristic of regenerator is incorporated in the thermodynamic model. The results obtained from the model show that under the same working pressure, the efficiency of the proposed engine is potentially higher than that of conventional ones and to achieve the same efficiency, the working pressure could be lower with the new mechanism. Its efficiency could be improved by reducing temperature difference between the regenerator and the cold/hot space, increasing the swept volume ratio, decreasing the liquid–gas ratio. To keep

  8. BWR fuel assembly bottom nozzle with one-way coolant flow valve

    International Nuclear Information System (INIS)

    Taleyarkhan, R.P.

    1987-01-01

    In a nuclear reactor having a flow of coolant/moderator fluid therein, at least one fuel assembly installed in the fluid flow, the fuel assembly is described comprising in combination: a bundle of elongated fuel rods disposed in side-by-side relationship so as to form an array of spaced fuel rods; an outer tubular flow channel surrounding the fuel rods so as to direct the flow of coolant/moderator fluid along the fuel rods; bottom and top nozzles mounted at opposite ends of the flow channel and having an inlet and outlet respectively for allowing entry and exit of the flow of coolant/moderator fluid into and from the flow channel and along the fuel rods therein; and a coolant flow direction control device operatively disposed in the bottom nozzle so as to open the inlet thereof to the flow of coolant/moderator fluid in an inflow direction into the flow channel through the bottom nozzle inlet but close the inlet to the flow of coolant/moderator fluid from the flow channel through the bottom nozzle inlet upon reversal of coolant/moderator fluid flow from the inflow direction

  9. Measurement of opening and closing angles of aortic valve prostheses in vivo using dual-source computed tomography: Comparison with those of manufacturers' in 10 different types

    International Nuclear Information System (INIS)

    Suh, Young Joo; Kim, Young Jin; Hong, Yoo Jin; Lee, Hye Jeong; Hur, Jin; Im, Dong Jin; Kim, Yun Jung; Choi, Byoung Wook

    2015-01-01

    The aims of this study were to compare opening and closing angles of normally functioning mechanical aortic valves measured on dual-source computed tomography (CT) with the manufacturers' values and to compare CT-measured opening angles according to valve function. A total of 140 patients with 10 different types of mechanical aortic valves, who underwent dual-source cardiac CT, were included. Opening and closing angles were measured on CT images. Agreement between angles in normally functioning valves and the manufacturer values was assessed using the interclass coefficient and the Bland-Altman method. CT-measured opening angles were compared between normal functioning valves and suspected dysfunctioning valves. The CT-measured opening angles of normally functioning valves and manufacturers' values showed excellent agreement for seven valve types (intraclass coefficient [ICC], 0.977; 95% confidence interval [CI], 0.962-0.987). The mean differences in opening angles between the CT measurements and the manufacturers' values were 1.2° in seven types of valves, 11.0° in On-X valves, and 15.5° in ATS valves. The manufacturers' closing angles and those measured by CT showed excellent agreement for all valve types (ICC, 0.953; 95% CI, 0.920-0.972). Among valves with suspected dysfunction, those with limitation of motion (LOM) and an increased pressure gradient (PG) had smaller opening angles than those with LOM only (p < 0.05). Dual-source cardiac CT accurately measures opening and closing angles in most types of mechanical aortic valves, compared with the manufacturers' values. Opening angles on CT differ according to the type of valve dysfunction and a decreased opening angle may suggest an elevated PG

  10. Mitral Valve Stenosis

    Science.gov (United States)

    ... the left ventricle from flowing backward. A defective heart valve fails to either open or close fully. Risk factors Mitral valve stenosis is less common today than it once was because the most common cause, ... other heart valve problems, mitral valve stenosis can strain your ...

  11. Fuel control apparatus of carburetor in deceleration

    Energy Technology Data Exchange (ETDEWEB)

    Ishii, N

    1974-11-20

    A fuel control valve for carburetors during deceleration operation is described for fuel conservation. The device cuts off the fuel supply to the cylinder during deceleration. The control valve is regulated by a magnetic switch, and the electrical current to the switch is controlled through a device sensible to the pressure difference to both sides of the throttle valve in the carburetor. When the cylinder becomes lower in pressure than the atmospheric pressure, the pressure activates the electrical current switch, thus activating the magnetic switch to close the fuel control valve. The device also prevents the engine from running after the ignition key is disconnected.

  12. Multinode analysis of small breaks for B and W's 205-fuel-assembly nuclear plants with internals vent valves

    International Nuclear Information System (INIS)

    Jones, R.C.; Dunn, B.M.; Parks, C.E.

    1976-03-01

    Multinode analyses were conducted for several small breaks in the reactor coolant system of B and W's 205-fuel-assembly nuclear plants with internals vent valves. The multinode blowdown code CRAFT was used to evaluate the hydrodynamics and transient water inventories of the reactor coolant system. The FOAM code was used to compute a swell level history for the core, and the THETA1-B code was used to perform transient fuel pin thermal calculations. Curves showing the parameters of interest are presented. The results are well within the Final Acceptance Criteria

  13. Multinode analysis of small breaks for B and W's 145-fuel-assembly nuclear plants with internals vent valves

    International Nuclear Information System (INIS)

    Parks, C.E.; Allen, R.J.; Cartin, L.R.

    1976-03-01

    Multinode analyses were conducted for several small breaks in the reactor coolant system of B and W's 145 fuel-assembly nuclear plants with internals vent valves. The multinode blowdown code CRAFT was used to evaluate the hydrodynamics and transient water inventories of the reactor coolant system. The FOAM code was used to compute a swell level history for the core, and the THETA1-B code was used to perform transient fuel pin thermal calculations. Curves showing the parameters of interest are presented. These results are well within the Final Acceptance Criteria

  14. Effects of structure parameters on flow and cavitation characteristics within control valve of fuel injector for modern diesel engine

    International Nuclear Information System (INIS)

    Wang, Chao; Li, Guo-Xiu; Sun, Zuo-Yu; Wang, Lan; Sun, Shu-Ping; Gu, Jiao-Jiao; Wu, Xiao-Jun

    2016-01-01

    Highlights: • The Schnerr-Sauer model was used to calculate the cavitation source term. • The development process and influencing factors of cavitation were studied. • The flow process inside control valve during the ball valve opened were studied. • The effects of the structure parameters of the control valve on the cavitation and flow were studied. - Abstract: Cavitation is a common phenomenon in diesel injector and has a strong influence on the internal flow. However, studies so far have focused on cavitation characteristics inside the nozzle. Its influence on the flow during control valve opening remains still unclear. In the paper, a computational study focused on the flow and cavitation phenomena within control valve has been reported and the effects of control valve’s structure parameters (including rounded edge, seal cone angle and outflowing control-orifice structure) on the flow and cavitation characteristics have been investigated in detail. Firstly the 3D model has been validated in terms of single injection quantity and fuel injection duration, showing a good consistency. And then, the development from sheet cavitation to cloud cavitation and the relationship between cavitation, pressure and velocity has been discussed. Based on the numerical results obtained, it is shown that not only the variation of pressure but also the velocity is the important factor which affects cavitation. The increase of the flow velocity reduces the pressure within the flow field which can aggravate the development of cavitation. As cavitation region increases, the fuel flow is hindered and the flow velocity decreases. However, the decrease of flow velocity has suppressed the development of cavitation. All of those variations form a cyclical process.

  15. Novel Active Combustion Control Valve

    Science.gov (United States)

    Caspermeyer, Matt

    2014-01-01

    This project presents an innovative solution for active combustion control. Relative to the state of the art, this concept provides frequency modulation (greater than 1,000 Hz) in combination with high-amplitude modulation (in excess of 30 percent flow) and can be adapted to a large range of fuel injector sizes. Existing valves often have low flow modulation strength. To achieve higher flow modulation requires excessively large valves or too much electrical power to be practical. This active combustion control valve (ACCV) has high-frequency and -amplitude modulation, consumes low electrical power, is closely coupled with the fuel injector for modulation strength, and is practical in size and weight. By mitigating combustion instabilities at higher frequencies than have been previously achieved (approximately 1,000 Hz), this new technology enables gas turbines to run at operating points that produce lower emissions and higher performance.

  16. The choice of the fuel assembly for VVER-1000 in a closed fuel cycle based on REMIX-technology

    International Nuclear Information System (INIS)

    Bobrov, E.; Alekseev, P.; Chibinyaev, A.; Teplov, P.; Dudnikov, A.

    2016-01-01

    REMIX (Regenerated Mixture) fuel is produced directly from a non-separated mix of recycled uranium and plutonium from reprocessed used fuel and the fabrication technology of such fuel is called REMIX-technology. This paper shows basic features of different fuel assembly (FA) application for VVER-1000 in a closed fuel cycle based on REMIX-technology. This investigation shows how the change in the water-fuel ratio in the VVER FA affects the fuel characteristics produced by REMIX technology during multiple recycling. It is shown that for for the traditional REMIX-fuel it does not make sense to change anything in the design of VVER FA, because there are no advantages in the fuel feed consumption. The natural uranium economy by the fifth cycle reached about 29%. In the case of the REMIX fuel based on uranium-plutonium from SNF MOX fuel, it would be appropriate to use fuel assemblies with a water-fuel ratio of 1.5

  17. Problem: Heart Valve Regurgitation

    Science.gov (United States)

    ... should be completely closed For example: Watch an animation of mitral valve regurgitation A leaking mitral valve ... Not Alone Popular Articles 1 Understanding Blood Pressure Readings 2 Sodium and Salt 3 Heart Attack Symptoms ...

  18. Aortic valve surgery - open

    Science.gov (United States)

    ... gov/ency/article/007408.htm Aortic valve surgery - open To use the sharing features on this page, ... separates the heart and aorta. The aortic valve opens so blood can flow out. It then closes ...

  19. Closed-Loop Pure Oxygen Static Feed Fuel Cell for Lunar Missions, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — In order to address the NASA lunar mission, DESC proposes to develop a proton exchange membrane (PEM) closed-loop pure oxygen fuel cell for application to lunar...

  20. Comparative analysis of methods and tools for open and closed fuel cycles modeling: MESSAGE and DESAE

    International Nuclear Information System (INIS)

    Andrianov, A.A.; Korovin, Yu.A.; Murogov, V.M.; Fedorova, E.V.; Fesenko, G.A.

    2006-01-01

    Comparative analysis of optimization and simulation methods by the example of MESSAGE and DESAE programs is carried out for nuclear power prospects and advanced fuel cycles modeling. Test calculations for open and two-component nuclear power and closed fuel cycle are performed. Auxiliary simulation-dynamic model is developed to specify MESSAGE and DESAE modeling approaches difference. The model description is given [ru

  1. Closing the fuel cycle - Reaching a public consensus

    International Nuclear Information System (INIS)

    Altshuler, B.; Janouch, F.; Wilson, R.

    1997-01-01

    There are three reasons for wanting nuclear power: it does not produce air pollution, or add to global warming; and it is effectively sustainable. What priority is attached to them? Is the possibility of alternate fuels being developed in the next 20 years large enough that mankind can afford not to develop the nuclear option as a possibility? Is the breeder reactor really needed, and when is the earliest time? Was the NAS 1994 (Panofsky) committee right that the existence of excess weapons plutonium present is a clear and present danger to the USA? If so how can we persuade the President to act? Is there a clear and present danger to other countries too? If so why are they still waiting for the U.S. to act? What are the true economic costs of reprocessing using the present PUREX process and can they be brought down? Is the extra cost of disposing of whole fuel rods vs separated waste, more or less than this? What, if any, is the difference (such as heat from Pu 238 ) between the ease of using ''reactor grade'' plutonium and ''weapons grade'' plutonium to make an atomic bomb? Can the difference be increased, and can this difference (if any) be translated into a lower cost for protection of or greater public acceptance of reactor grade plutonium? What could be an international research effort for a better fuel cycle? e.g: Introducing an IFR fuel cycle into Beloyarsk, Monju and/or Phoenix? Introducing a thorium cycle? Has anyone carefully Recorded, Understood and Explained the past history of breeder reactor technology both of accidents, and of failures and successes? If so, where is it? If not, why not? Is the report by Clarke of NRPB in UK on plutonium toxicity that belies the claim that it is unusually toxic widely known? If not, why not? Can the MAYAK experience with misuse of plutonium be used to help in public understanding? Since India and Pakistan will not sign NPT, can more imaginative, quiet, talks with Indian and Pakistani leaders persuade them to come to

  2. Face-Sealing Butterfly Valve

    Science.gov (United States)

    Tervo, John N.

    1992-01-01

    Valve plate made to translate as well as rotate. Valve opened and closed by turning shaft and lever. Interactions among lever, spring, valve plate, and face seal cause plate to undergo combination of translation and rotation so valve plate clears seal during parts of opening and closing motions.

  3. Closing the fuel cycle: the evidence in the long run

    International Nuclear Information System (INIS)

    Devezeaux de Lavergne, J.G.; L'Epine, P. de; Pehuet, F.; Pinson, P.

    1996-01-01

    The purpose of the contribution is to explain the following points: (i) The choice of the Reprocessing Conditioning Recycling (RCR) policy means benefitting from a flexible technology in the medium term, with the possibility of a periodic review and fine tuning of the back-end flows and quantities (e.g. the plutonium inventory). (ii) Long term fuel cycle management in Germany is sustainable, on the basis of progressive multirecycling steps that will control the plutonium baseload inventory; from todays achievements, on can reckon such a scheme is confronted with no major technical limit. An attractive feature of the recycling scheme is to open the way to future advanced processes, such as minimisation of ultimate waste volume or partition and transmutation of TRU, if needed. (iii) The RCR policy is already cost efficient and well be clearly advantageous in the long run. To illustrate and quantify these points, an aggregated model of annual fuel requirements in Germany has been elaborated; it has been applied to the period 1979-2029, thus integrating past and future requirements. Some results are presented hereafter. (orig./DG)

  4. Dynamic analysis of once-through and closed fuel cycle economics using Monte Carlo simulation

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Sungyeol, E-mail: csy@kaeri.re.kr; Lee, Hyo Jik, E-mail: hyojik@kaeri.re.kr; Ko, Won Il, E-mail: nwiko@kaeri.re.kr

    2014-10-01

    Highlights: • Dynamic behavior of system costs, both reactor and fuel cycle costs, is analyzed. • Relative economics of once-through and closed fuel cycles is explored. • Probabilistic approaches are adopted for levelized electricity generation costs. • Main cost drivers for cost gaps between once-through and closed cycles are identified. - Abstract: Although no consensus about the best approach to manage spent fuels has been achieved, economics is one of the major criteria for assessing and selecting acceptable management options. This study compares the reactor and fuel cycle costs of the closed system associated with sodium-cooled fast reactors and pyroprocessing versus the once-through system. We specifically investigated the fuel cycle transition cases of the Republic of Korea from 2013 to 2100. The results revealed that the closed system (34.00 mills/kWh as a mean value) could be more expensive than the once-through system (32.75 mills/kWh). In contrast, the once-through fuel cycle costs (8.31 mills/kWh), excluding reactor costs, were projected to be greater than the closed fuel cycle costs (7.77 mills/kWh) because of the increased costs of interim storage estimated by the Korean government and the limited contribution of backend fuel cycle components to the discounted costs. The capital cost of sodium-cooled fast reactor is the largest component contributing to the cost gap between the two systems. Among fuel cycle components, pyroprocessing has the largest uncertainty contribution to the cost gap. We also calculated the breakeven unit costs of SFR capital cost and PWR spent fuel pyroprocessing cost.

  5. Stress analysis on the valve of the rotating shield, coupled with fuel element loading-unloading machine in a PWR pressure vessel

    International Nuclear Information System (INIS)

    Albuquerque, L.B. de; Jesus Miranda, C.A. de.

    1992-01-01

    A finite element static analysis was performed with the valve of the Rotating Shield (RS) which is coupled with the Fuel. Element Loading-Unloading Machine under OBE earthquake. The applied leads were obtained from a previous seismic analysis with the response spectrum method of the MTC under OBE load. A 3-D model with shell elements was developed for the valve body and for a part of the RS. The ANSYS program, version 4.4 A, was used. The two main scopes of this work were to verify the valve stresses and the functionality of its moving parts during the earthquake. (author)

  6. Heart Valve Diseases

    Science.gov (United States)

    Your heart has four valves. Normally, these valves open to let blood flow through or out of your heart, and then shut to keep it from flowing ... close tightly. It's one of the most common heart valve conditions. Sometimes it causes regurgitation. Stenosis - when ...

  7. Closed Nuclear Fuel Cycle Technologies to Meet Near-Term and Transition Period Requirements

    International Nuclear Information System (INIS)

    Collins, E.D.; Felker, L.K.; Benker, D.E.; Campbell, D.O.

    2008-01-01

    A scenario that very likely fits conditions in the U.S. nuclear power industry and can meet the goals of cost minimization, waste minimization, and provisions of engineered safeguards for proliferation resistance, including no separated plutonium, to close the fuel cycle with full actinide recycle is evaluated. Processing aged fuels, removed from the reactor for 30 years or more, can provide significant advantages in cost reduction and waste minimization. The UREX+3 separations process is being developed to separate used fuel components for reuse, thus minimizing waste generation and storage in geologic repositories. Near-term use of existing and new thermal spectrum reactors can be used initially for recycle actinide transmutation. A transition period will eventually occur, when economic conditions will allow commercial deployment of fast reactors; during this time, recycled plutonium can be diverted into fast reactor fuel and conversion of depleted uranium into additional fuel material can be considered. (authors)

  8. Closed Nuclear Fuel Cycle Technologies to Meet Near-Term and Transition Period Requirements

    Energy Technology Data Exchange (ETDEWEB)

    Collins, E.D.; Felker, L.K.; Benker, D.E.; Campbell, D.O. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee, 37831-6152 (United States)

    2008-07-01

    A scenario that very likely fits conditions in the U.S. nuclear power industry and can meet the goals of cost minimization, waste minimization, and provisions of engineered safeguards for proliferation resistance, including no separated plutonium, to close the fuel cycle with full actinide recycle is evaluated. Processing aged fuels, removed from the reactor for 30 years or more, can provide significant advantages in cost reduction and waste minimization. The UREX+3 separations process is being developed to separate used fuel components for reuse, thus minimizing waste generation and storage in geologic repositories. Near-term use of existing and new thermal spectrum reactors can be used initially for recycle actinide transmutation. A transition period will eventually occur, when economic conditions will allow commercial deployment of fast reactors; during this time, recycled plutonium can be diverted into fast reactor fuel and conversion of depleted uranium into additional fuel material can be considered. (authors)

  9. Fuel fired heat sources

    Energy Technology Data Exchange (ETDEWEB)

    Ortlinghaus, U

    1977-09-08

    Fuel fired heat sources with a valve-controlled ignition and main burner, whose flame is monitored and whose control valve is closed or opened by a controller according to the control deviation between actual and reference heat source temperature, previously suffered the disadvantage of high consumption of ignition gas. According to the invention this disadvantage is avoided by closing the ignition valve from the controller via a delay unit and having the delay time of the delay unit controlled either by the temperature measured by the sensor or increasing it with increasing deviation of the actual value of pre-temperature from the reference value of the pre-temperature.

  10. A modelling study into the effects of variable valve timing on the gas exchange process and performance of a 4-valve DI homogeneous charge compression ignition (HCCI) engine

    International Nuclear Information System (INIS)

    Mahrous, A-F.M.; Potrzebowski, A.; Wyszynski, M.L.; Xu, H.M.; Tsolakis, A.; Luszcz, P.

    2009-01-01

    Homogeneous charge compression ignition (HCCI) combustion mode is a relatively new combustion technology that can be achieved by using specially designed cams with reduced lift and duration. The auto-ignition in HCCI engine can be facilitated by adjusting the timing of the exhaust-valve-closing and, to some extent, the timing of the intake-valve-opening so as to capture a proportion of the hot exhaust gases in the engine cylinder during the gas exchange process. The effects of variable valve timing strategy on the gas exchange process and performance of a 4-valve direct injection HCCI engine were computationally investigated using a 1D fluid-dynamic engine cycle simulation code. A non-typical intake valve strategy was examined; whereby the intake valves were assumed to be independently actuated with the same valve-lift profile but at different timings. Using such an intake valves strategy, the obtained results showed that the operating range of the exhaust-valve-timing within which the HCCI combustion can be facilitated and maintained becomes much wider than that of the typical intake-valve-timing case. Also it was found that the engine parameters such as load and volumetric efficiency are significantly modified with the use of the non-typical intake-valve-timing. Additionally, the results demonstrated the potential of the non-typical intake-valve strategy in achieving and maintaining the HCCI combustion at much lower loads within a wide range of valve timings. Minimizing the pumping work penalty, and consequently improving the fuel economy, was shown as an advantage of using the non-typical intake-valve-timing with the timing of the early intake valve coupled with a symmetric degree of exhaust-valve-closing timing

  11. A modelling study into the effects of variable valve timing on the gas exchange process and performance of a 4-valve DI homogeneous charge compression ignition (HCCI) engine

    Energy Technology Data Exchange (ETDEWEB)

    Mahrous, A-F.M. [School of Mechanical Engineering, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Lecturer at the Department of Mechanical Power Engineering, Faculty of Engineering (Shebin El-Kom), Menoufiya University, Shebin El-Kom (Egypt); Potrzebowski, A.; Wyszynski, M.L.; Xu, H.M.; Tsolakis, A.; Luszcz, P. [School of Mechanical Engineering, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)

    2009-02-15

    Homogeneous charge compression ignition (HCCI) combustion mode is a relatively new combustion technology that can be achieved by using specially designed cams with reduced lift and duration. The auto-ignition in HCCI engine can be facilitated by adjusting the timing of the exhaust-valve-closing and, to some extent, the timing of the intake-valve-opening so as to capture a proportion of the hot exhaust gases in the engine cylinder during the gas exchange process. The effects of variable valve timing strategy on the gas exchange process and performance of a 4-valve direct injection HCCI engine were computationally investigated using a 1D fluid-dynamic engine cycle simulation code. A non-typical intake valve strategy was examined; whereby the intake valves were assumed to be independently actuated with the same valve-lift profile but at different timings. Using such an intake valves strategy, the obtained results showed that the operating range of the exhaust-valve-timing within which the HCCI combustion can be facilitated and maintained becomes much wider than that of the typical intake-valve-timing case. Also it was found that the engine parameters such as load and volumetric efficiency are significantly modified with the use of the non-typical intake-valve-timing. Additionally, the results demonstrated the potential of the non-typical intake-valve strategy in achieving and maintaining the HCCI combustion at much lower loads within a wide range of valve timings. Minimizing the pumping work penalty, and consequently improving the fuel economy, was shown as an advantage of using the non-typical intake-valve-timing with the timing of the early intake valve coupled with a symmetric degree of exhaust-valve-closing timing. (author)

  12. Assessment of the environmental footprint of nuclear energy systems. Comparison between closed and open fuel cycles

    International Nuclear Information System (INIS)

    Poinssot, Ch.; Bourg, S.; Ouvrier, N.; Combernoux, N.; Rostaing, C.; Vargas-Gonzalez, M.; Bruno, J.

    2014-01-01

    Energy perspectives for the current century are dominated by the anticipated significant increase of energy needs. Particularly, electricity consumption is anticipated to increase by a factor higher than two before 2050. Energy choices are considered as structuring political choices that implies a long-standing and stable policy based on objective criteria. LCA (life cycle analysis) is a structured basis for deriving relevant indicators which can allow the comparison of a wide range of impacts of different energy sources. Among the energy-mix, nuclear power is anticipated to have very low GHG-emissions. However, its viability is severely addressed by the public opinion after the Fukushima accident. Therefore, a global LCA of the French nuclear fuel cycle was performed as a reference model. Results were compared in terms of impact with other energy sources. It emphasized that the French nuclear energy is one of the less impacting energy, comparable with renewable energy. In a second, part, the French scenario was compared with an equivalent open fuel cycle scenario. It demonstrates that an open fuel cycle would require about 16% more natural uranium, would have a bigger environmental footprint on the “non radioactive indicators” and would produce a higher volume of high level radioactive waste. - Highlights: • A life cycle analysis of the French close nuclear fuel cycle is performed. • The French nuclear energy is one of the less environmental impacting energy. • The French close fuel cycle is compared to an equivalent open fuel cycle. • An open fuel cycle would have a bigger environmental impact than the French fuel cycle. • Spent nuclear fuel recycling has a positive impact on the environmental footprint

  13. A proliferation-resistant closed nuclear fuel cycle with radiation-equivalent disposal of radioactive waste

    International Nuclear Information System (INIS)

    Adamov, E.O.; Gabaraev, B.A.; Ganev, I.K.; Lopatkin, A.V.; Orlov, V.V.

    1998-01-01

    The growing energy demand in the next century can be met by large-scale nuclear power that can be deployed around fast reactors operating in a closed U-Pu cycle. The main requirements to the future fuel cycle are 1) reduction of the radiation risk from radioactive waste owing to transmutation of the most hazardous long-lived actinides and fission products in reactors and due to thorough treatment of radwaste to remove these elements, with provision of a balance between the activity of waste put to final disposal and that of uranium extracted from earth; 2) no possibility to use closed cycle facilities for Pu extraction from spent fuel for the purpose of weapons production; physical protection of fuel against thefts (nonproliferation). (author)

  14. Critical experiments supporting close proximity water storage of power reactor fuel. Technical progress report

    International Nuclear Information System (INIS)

    Baldwin, M.N.; Hoovler, G.S.; Eng, R.L.; Welfare, F.G.

    1979-07-01

    Close-packed storage of LWR fuel assemblies is needed in order to expand the capacity of existing underwater storage pools. This increased capacity is required to accommodate the large volume of spent fuel produced by prolonged onsite storage. To provide benchmark criticality data in support of this effort, 20 critical assemblies were constructed that simulated a variety of close-packed LWR fuel storage configurations. Criticality calculations using the Monte Carlo KENO-IV code were performed to provide an analytical basis for comparison with the experimental data. Each critical configuration is documented in sufficient detail to permit the use of these data in validating calculational methods according to ANSI Standard N16.9-1975

  15. Swing check valve

    International Nuclear Information System (INIS)

    Eminger, H.E.

    1977-01-01

    A swing check valve which includes a valve body having an inlet and outlet is described. A recess in the valve body designed to hold a seal ring and a check valve disc swingable between open and closed positions. The disc is supported by a high strength wire secured at one end in a support spacer pinned through bearing blocks fixed to the valve body and at its other end in a groove formed on the outer peripheral surface of the disc. The parts are designed and chosen such to provide a lightweight valve disc which is held open by minimum velocity of fluid flowing through the valve which thus reduces oscillations and accompanying wear of bearings supporting the valve operating parts. (Auth.)

  16. Research and Development of Miniaturized Fuel Evaporation Closed Chamber for Motorcycle

    Directory of Open Access Journals (Sweden)

    Hong Bin

    2016-01-01

    Full Text Available With the increasingly serious environmental pollution, pollution emissions of motorcycles had gradually been concerned in all developed countries. But the fuel evaporative emissions had not attracted sufficient attention and its test equipment was far from perfect. Thus, this paper addressed the miniaturized problems of closed chamber. On the basis of analyzing fuel evaporative emission regulations and the features of closed room, technical solutions are determined and a prototype was successfully developed. The paper successfully resolved the seal problem and innovatively developed the pressure balance system and the temperature and humidity regulation system. After experimental verification, the prototype had reliable performance and stable operation. And it met the requirements of the relevant standards and it was also equivalent to imported equipments. Thus, this paper successfully resolved the miniaturized problems of closed chamber.

  17. Some conditions and prospects of transition to closed fuel cycle in Russia

    International Nuclear Information System (INIS)

    Lependin, A.V.; Oussanov, V.I.; Lependina, E.V.; Ioughai, S.V.

    2001-01-01

    Nuclear policy of Russia is based on the necessity of closure of nuclear fuel cycle. But at the same time schedule of such a going is not defined. In this study some conditions and possible time-frames of going the nuclear fuel cycle of Russia to closure are discussed. Naturally, the main condition is revival of Russian economy wherein nuclear power will turn to be necessary in a number of Russian regions. But the question is whether closure of nuclear cycle strategy will be implemented in the near future or nuclear power will develop based on open fuel cycle over a long period of time? at present economic circumstances in Russia has formed in such a way that economics of current projects is not favourable to going to closure of cycle due to high capital investment cost and low fuel component of costs, due to low cost of natural uranium. Ecological analysis performed within the framework of external cost model also does not suggest that closed cycle has essential advantages at present, but also in sight. The authors have considered a model including not only external costs but also total resources expenditures with long-term power development. In the framework of such a method it can be demonstrated that closed fuel cycle has some important advantages taking into account not only tasks of immediate future, but power development strategy for the period of 30-50 years. Under conditions of nuclear capacities increase (to 30-50 GW) limitation of cheap uranium resources available in Russia will assume a new significance. Approach of prices at the back-end stages of nuclear fuel cycle to West Europe level also will favour to going to a closed fuel cycle. More severe ecological requirements answering to a sustainable development concept also will make a contribution. Closure of fuel cycle can be significantly accelerated in the case of implementation of weapon plutonium utilization program. The factors mentioned above facilitate evenly to going to a closed nuclear fuel

  18. Modeling, Parameters Identification, and Control of High Pressure Fuel Cell Back-Pressure Valve

    Directory of Open Access Journals (Sweden)

    Fengxiang Chen

    2014-01-01

    Full Text Available The reactant pressure is crucial to the efficiency and lifespan of a high pressure PEMFC engine. This paper analyses a regulated back-pressure valve (BPV for the cathode outlet flow in a high pressure PEMFC engine, which can achieve precisely pressure control. The modeling, parameters identification, and nonlinear controller design of a BPV system are considered. The identified parameters are used in designing active disturbance rejection controller (ADRC. Simulations and extensive experiments are conducted with the xPC Target and show that the proposed controller can not only achieve good dynamic and static performance but also have strong robustness against parameters’ disturbance and external disturbance.

  19. Internal combustion engine with rotary valve assembly having variable intake valve timing

    Science.gov (United States)

    Hansen, Craig N.; Cross, Paul C.

    1995-01-01

    An internal combustion engine has rotary valves associated with movable shutters operable to vary the closing of intake air/fuel port sections to obtain peak volumetric efficiency over the entire range of speed of the engine. The shutters are moved automatically by a control mechanism that is responsive to the RPM of the engine. A foot-operated lever associated with the control mechanism is also used to move the shutters between their open and closed positions.

  20. Critical experiments supporting close proximity water storage of power reactor fuel. Technical progress report, July 1, 1978-September 30, 1978

    Energy Technology Data Exchange (ETDEWEB)

    Baldwin, M.N.; Hoovler, G.S.; Eng, R.L.; Welfare, F.G.

    1978-11-01

    Experimental measurements are being taken on critical configurations of clusters of fuel rods mocking up LWR-type fuel elements in close proximity water storage. The results will serve to benchmark the computer codes used in designing nuclear power reactor fuel storage racks. KENO calculations of Cores I to VI are within two standard deviations of the measured k/sub eff/ values.

  1. Definition of breeding gain for the closed fuel cycle and application to a gas cooled fast reactor

    International Nuclear Information System (INIS)

    Van Rooijen, W. F. G.; Kloosterman, J. L.; Van Der Hagen, T. H. J. J.; Van Dam, H.

    2006-01-01

    In this paper a definition is given for the Breeding Gain (BG) of a nuclear reactor, taking into account compositional changes of the fuel during irradiation, cool down and reprocessing. A definition is given for the reactivity weights required to calculate BG. To calculate the effects of changes in the initial fuel composition on BG, first order nuclide perturbation theory is used. The theory is applied to the fuel cycle of GFR600, a 600 MWth Generation IV Gas Cooled Fast Reactor. This reactor should have a closed fuel cycle, with a BG equal to zero, breeding just enough new fuel during irradiation to allow refueling by only adding fertile material. All Heavy Metal is recycled in the closed fuel cycle. The result is that a closed fuel cycle is possible if the reprocessing has low losses ( 238 U, 15% Pu, and low amounts of the Minor Actinides. (authors)

  2. Magnetic Check Valve

    Science.gov (United States)

    Morris, Brian G.; Bozeman, Richard J., Jr.

    1994-01-01

    Poppet in proposed check valve restored to closed condition by magnetic attraction instead of spring force. Oscillations suppressed, with consequent reduction of wear. Stationary magnetic disk mounted just upstream of poppet, also containing magnet. Valve body nonmagnetic. Forward pressure or flow would push poppet away from stationary magnetic disk so fluid flows easily around poppet. Stop in valve body prevents poppet from being swept away. When flow stopped or started to reverse, magnetic attraction draws poppet back to disk. Poppet then engages floating O-ring, thereby closing valve and preventing reverse flow. Floating O-ring facilitates sealing at low loads.

  3. Fast molten salt reactor-transmuter for closing nuclear fuel cycle on minor actinides

    International Nuclear Information System (INIS)

    Dudnikov, A. A.; Alekseev, P. N.; Subbotin, S. A.

    2007-01-01

    Creation fast critical molten salt reactor for burning-out minor actinides and separate long-living fission products in the closed nuclear fuel cycle is the most perspective and actual direction. The reactor on melts salts - molten salt homogeneous reactor with the circulating fuel, working as burner and transmuter long-living radioactive nuclides in closed nuclear fuel cycle, can serve as an effective ecological cordon from contamination of the nature long-living radiotoxic nuclides. High-flux fast critical molten-salt nuclear reactors in structure of the closed nuclear fuel cycle of the future nuclear power can effectively burning-out / transmute dangerous long-living radioactive nuclides, make radioisotopes, partially utilize plutonium and produce thermal and electric energy. Such reactor allows solving the problems constraining development of large-scale nuclear power, including fueling, minimization of radioactive waste and non-proliferation. Burning minor actinides in molten salt reactor is capable to facilitate work solid fuel power reactors in system NP with the closed nuclear fuel cycle and to reduce transient losses at processing and fabrications fuel pins. At substantiation MSR-transmuter/burner as solvents fuel nuclides for molten-salt reactors various salts were examined, for example: LiF - BeF2; NaF - LiF - BeF2; NaF-LiF ; NaF-ZrF4 ; LiF-NaF -KF; NaCl. RRC 'Kurchatov institute' together with other employees have developed the basic design reactor installations with molten salt reactor - burner long-living nuclides for fluoride fuel composition with the limited solubility minor actinides (MAF3 10 mol %) allows to develop in some times more effective molten salt reactor with fast neutron spectrum - burner/ transmuter of the long-living radioactive waste. In high-flux fast reactors on melts salts within a year it is possible to burn ∼300 kg minor actinides per 1 GW thermal power of reactor. The technical and economic estimation given power

  4. Physics studies of weapons plutonium disposition in the Integral Fast Reactor closed fuel cycle

    International Nuclear Information System (INIS)

    Hill, R.N.; Wade, D.C.; Liaw, J.R.; Fujita, E.K.

    1995-01-01

    The core performance impact of weapons plutonium introduction into the Integral Fast Reactor (IFR) closed fuel cycle is investigated by comparing three disposition scenarios: a power production mode, a moderate destruction mode, and a maximum destruction mode, all at a constant heat rating of 840 MW(thermal). For each scenario, two fuel cycle models are evaluated: cores using weapons material as the sole source of transuranics in a once-through mode and recycle cores using weapons material only as required for a makeup feed. In addition, the impact of alternative feeds (recycled light water reactor or liquid-metal reactor transuranics) on burner core performance is assessed. Calculated results include mass flows, detailed isotopic distributions, neutronic performance characteristics, and reactivity feedback coefficients. In general, it is shown that weapons plutonium does not have an adverse effect on IFR core performance characteristics; also, favorable performance can be maintained for a wide variety of feed materials and fuel cycle strategies

  5. A safeguards approach for a closed geological repository for spent fuel

    International Nuclear Information System (INIS)

    Meer, K. van der; Carchon, R.

    1999-01-01

    After closure of a geological repository a diversion of fissile material can only take place by excavating spent fuel containers and bringing them to the surface. Therefore mining activities are required, either by reopening the original shaft, by creating a new shaft or by approaching the containers underground via a neighbouring mine The recovery time of the stored spent fuel plays an important role in the determination of the timeliness criterion and, therefore, the inspection frequency of the site. Obviously, this frequency can create a financial constraint due to the infinite character of the spent fuel storage in a geological repository. Anomalies for detection of a possible diversion are undeclared mining activities. The safeguards approach has to assure Continuity Of Knowledge (COK) of the fissile material. By consequence, a safeguards approach that is developed for a closed repository, is influenced by the safeguards approach applied to an open. repository and a conditioning facility. A closed repository is verified by DIV. To perform the DIV satellite monitoring could be performed for surface verification and e.g. seismic techniques could be used for verification that no undeclared mining activities underground take place. Visual inspections of the site by inspectors have to reveal concealment methods used by a potential diverter. These measures should guarantee that the disposed spent fuel remains untouched. (author)

  6. Analysis of changes in the fuel component of the cost of electricity in the transition to a closed fuel cycle in nuclear power system

    Energy Technology Data Exchange (ETDEWEB)

    Gurin, Andrey V. [National Research Centre ' ' Kurchatov Institute' ' , Moscow (Russian Federation); Alekseev, P.N.

    2017-09-15

    This paper presents a study of scenarios of transition to a closed fuel cycle in the system of nuclear power, built basing on resource availability requirements at the stage of full life-cycle reactors. Conventionally, there are three main scenarios for the development of nuclear energy: with VVER reactors operating in an open fuel cycle; with VVER reactors operating in a closed fuel cycle; and co-operating VVER and BN, operating in a closed fuel cycle. For the considered scenarios, a quantitative estimation of change in time of material balances were performed, including spent fuel balance, balance of plutonium, reprocessed and depleted uranium, radioactive waste, and the analysis of the fuel component of the cost of electricity.

  7. Analysis of changes in the fuel component of the cost of electricity in the transition to a closed fuel cycle in nuclear power system

    International Nuclear Information System (INIS)

    Gurin, Andrey V.; Alekseev, P.N.

    2017-01-01

    This paper presents a study of scenarios of transition to a closed fuel cycle in the system of nuclear power, built basing on resource availability requirements at the stage of full life-cycle reactors. Conventionally, there are three main scenarios for the development of nuclear energy: with VVER reactors operating in an open fuel cycle; with VVER reactors operating in a closed fuel cycle; and co-operating VVER and BN, operating in a closed fuel cycle. For the considered scenarios, a quantitative estimation of change in time of material balances were performed, including spent fuel balance, balance of plutonium, reprocessed and depleted uranium, radioactive waste, and the analysis of the fuel component of the cost of electricity.

  8. Cryogenic Cam Butterfly Valve

    Science.gov (United States)

    McCormack, Kenneth J. (Inventor)

    2016-01-01

    A cryogenic cam butterfly valve has a body that includes an axially extending fluid conduit formed there through. A disc lug is connected to a back side of a valve disc and has a circular bore that receives and is larger than a cam of a cam shaft. The valve disc is rotatable for a quarter turn within the body about a lug axis that is offset from the shaft axis. Actuating the cam shaft in the closing rotational direction first causes the camming side of the cam of the cam shaft to rotate the disc lug and the valve disc a quarter turn from the open position to the closed position. Further actuating causes the camming side of the cam shaft to translate the valve disc into sealed contact with the valve seat. Opening rotational direction of the cam shaft reverses these motions.

  9. Convex optimisation approach to constrained fuel optimal control of spacecraft in close relative motion

    Science.gov (United States)

    Massioni, Paolo; Massari, Mauro

    2018-05-01

    This paper describes an interesting and powerful approach to the constrained fuel-optimal control of spacecraft in close relative motion. The proposed approach is well suited for problems under linear dynamic equations, therefore perfectly fitting to the case of spacecraft flying in close relative motion. If the solution of the optimisation is approximated as a polynomial with respect to the time variable, then the problem can be approached with a technique developed in the control engineering community, known as "Sum Of Squares" (SOS), and the constraints can be reduced to bounds on the polynomials. Such a technique allows rewriting polynomial bounding problems in the form of convex optimisation problems, at the cost of a certain amount of conservatism. The principles of the techniques are explained and some application related to spacecraft flying in close relative motion are shown.

  10. The benefits of a fast reactor closed fuel cycle in the UK

    International Nuclear Information System (INIS)

    Gregg, R.; Hesketh, K.

    2013-01-01

    The work has shown that starting a fast reactor closed fuel cycle in the UK, requires virtually all of Britain's existing and future PWR spent fuel to be reprocessed, in order to obtain the plutonium needed. The existing UK Pu stockpile is sufficient to initially support only a modest SFR 'closed' fleet assuming spent fuel can be reprocessed shortly after discharge (i.e. after two years cooling). For a substantial fast reactor fleet, most Pu will have to originate from reprocessing future spent PWR fuel. Therefore, the maximum fast reactor fleet size will be limited by the preceding PWR fleet size, so scenarios involving fast reactors still require significant quantities of uranium ore indirectly. However, once a fast reactor fuel cycle has been established, the very substantial quantities of uranium tails in the UK would ensure there is sufficient material for several centuries. Both the short and long term impacts on a repository have been considered in this work. Over the short term, the decay heat emanating from the HLW and spent fuel will limit the density of waste within a repository. For scenarios involving fast reactors, the only significant heat bearing actinide content will be present in the final cores, resulting in a 50% overall reduction in decay energy deposited within the repository when compared with an equivalent open fuel cycle. Over the longer term, radiological dose becomes more important. Total radiotoxicity (normalised by electricity generated) is lower for scenarios with Pu recycle after 2000 years. Scenarios involving fast reactors have the lowest radiotoxicity since the quantities of certain actinides (Np, Pu and Am) eventually stabilise. However, total radiotoxicity as a measure of radiological risk does not account for differences in radionuclide mobility once in repository. Radiological dose is dominated by a small number of fission products so is therefore not affected significantly by reactor type or recycling strategy (since the

  11. Multinode analysis of small breaks for B and W's 177-fuel-assembly nuclear plants with raised loop arrangement and internals vent valves

    International Nuclear Information System (INIS)

    Cartin, L.R.; Hill, J.M.; Parks, C.E.

    1976-03-01

    Multinode analyses were conducted for several small breaks in the reactor coolant system of B and W's 177-fuel-assembly nuclear plants with a raised loop arrangement and internals vent valves. The multinode blowdown code CRAFT was used to evaluate the hydrodynamics and transient water inventories of the reactor coolant system. The FOAM code was used to compute a swell level history for the core, and THETAL-B was used to perform transient fuel pin thermal calculations. Curves showing parameters of interest are presented. The results of these analyses are acceptable within the guidelines set forth in the Final Acceptance Criteria

  12. Heart valve surgery

    Science.gov (United States)

    ... replacement; Valve repair; Heart valve prosthesis; Mechanical valves; Prosthetic valves ... surgery. Your heart valve has been damaged by infection ( endocarditis ). You have received a new heart valve ...

  13. Physics studies of weapons plutonium disposition in the IFR closed fuel cycle

    International Nuclear Information System (INIS)

    Hill, R.N.; Wade, D.C.; Liaw, J.R.; Fujita, E.K.

    1994-01-01

    The core performance impact of weapons plutonium introduction into the IFR closed fuel cycle is investigated by comparing three disposition scenarios: a power production mode, a moderate destruction mode, and a maximum destruction mode all at a constant heat rating of 840 MWt. For each scenario, two fuel cycle models are evaluated: cores using weapons material as the sole source of transuranics in a once-through mode, and recycle corns using weapons material only as required for a make-up feed. Calculated results include mass flows, detailed isotopic distributions, neutronic performance characteristics, and reactivity feedback coefficients. In general, it is shown that weapons plutonium feed does not have an adverse impact on IFR core performance characteristics

  14. Closed fuel cycle and contemporary tendencies of the nuclear facilities development

    International Nuclear Information System (INIS)

    Lelek, V.; Hron, M.

    2003-01-01

    The decision to develop nuclear facility is given not only through technical and financial arguments, but sometimes even the greater weight is on political, general safety and public acceptance reasons. Moreover a responsible statement about financial needs is at the beginning of the study possible only with a great error (roughly speaking - factor of two) and a time estimation up to the industrial facilities is about fifteen or even more years. If the technical development and realization is successful, we can express a more responsible conclusion only in such long time intervals. During such long periods, the criteria for political and financial decisions could be changed and the technical development will necessary follow the new situation with a change in the stream of money. On the other side, the stream of money into technology leads to a more precise forecast and a more responsible decision for future realizations. We shall try, in the paper, to reflect technical problems in the closed fuel cycle (like solid and liquid fuel options) with the public demands (refusing of nuclear energy and spent fuel disposal generally, preferring waste less technologies) and political safety aspects (nonproliferation, spent fuel storages). There will be a special attention devoted to such problems in smaller countries, where demands for energy cannot be covered by local classical sources and nuclear energy and spent fuel are already long time reality. The organizational measures and tendencies will be analyzed how to compose sufficiently great and qualified collectives to be able to overcome from the local final disposal development to the common technology realizing practically closed fuel cycle and enabling decomposition of water for the hydrogen production during the first half of this century. Overview information will be given about the Czech national technical program within the EU Program (MOST Project) and within the cooperation with Russian institutes in the molten

  15. Flow and mixing of gas in cylinder of a stratified charge engine with two intake valves. Effects of late closing valve timing and intake port configurations; Kyuki nibenshiki sojo kyuki engine no cylinder nai gas ryudo to kongo. Osotoji valve timing oyobi port keijo ni yoru eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Charoenphonphanich, C; Niwa, H; Ennoji, H; Iijima, T [Tokai University, Tokyo (Japan)

    1997-10-01

    A numerical analysis of the flow and mixing of rich mixture and air inducted into the cylinder through each of the two intake ports of a stratified charge engine have been carried out. Numerical calculations were performed by finite volume method for three types of the intake port configurations: inverse V type, parallel type and V type and two types of valve timing; conventional and late closing (Miller cycle). Velocity field, turbulent kinetic energy and distribution of mixture concentration in the cylinder were examined. 3 refs., 10 figs.

  16. Redo mitral valve surgery

    Directory of Open Access Journals (Sweden)

    Redoy Ranjan

    2018-03-01

    Full Text Available This study is based on the findings of a single surgeon’s practice of mitral valve replacement of 167 patients from April 2005 to June 2017 who developed symptomatic mitral restenosis after closed or open mitral commisurotomy. Both clinical and color doppler echocardiographic data of peri-operative and six months follow-up period were evaluated and compared to assess the early outcome of the redo mitral valve surgery. With male-female ratio of 1: 2.2 and after a duration of 6 to 22 years symptom free interval between the redo procedures, the selected patients with mitral valve restenosis undergone valve replacement with either mechanical valve in 62% cases and also tissue valve in 38% cases. Particular emphasis was given to separate the adhered pericardium from the heart completely to ameliorate base to apex and global contraction of the heart. Besides favorable post-operative clinical outcome, the echocardiographic findings were also encouraging as there was statistically significant increase in the mitral valve area and ejection fraction with significant decrease in the left atrial diameter, pressure gradient across the mitral valve and pulmonary artery systolic pressure. Therefore, in case of inevitable mitral restenosis after closed or open commisurotomy, mitral valve replacement is a promising treatment modality.

  17. Closed loop engine control for regulating NOx emissions, using a two-dimensional fuel-air curve

    Science.gov (United States)

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

    2007-01-30

    An engine control strategy that ensures that NOx emissions from the engine will be maintained at an acceptable level. The control strategy is based on a two-dimensional fuel-air curve, in which air manifold pressure (AMP) is a function of fuel header pressure and engine speed. The control strategy provides for closed loop NOx adjustment to a base AMP value derived from the fuel-air curve.

  18. Introducing close-range photogrammetry for characterizing forest understory plant diversity and surface fuel structure at fine scales

    Science.gov (United States)

    Benjamin C. Bright; E. Louise Loudermilk; Scott M. Pokswinski; Andrew T. Hudak; Joseph J. O' Brien

    2016-01-01

    Methods characterizing fine-scale fuels and plant diversity can advance understanding of plant-fire interactions across scales and help in efforts to monitor important ecosystems such as longleaf pine (Pinus palustris Mill.) forests of the southeastern United States. Here, we evaluate the utility of close-range photogrammetry for measuring fuels and plant...

  19. Nuclear material attractiveness: an assessment of material associated with a closed fuel cycle

    International Nuclear Information System (INIS)

    Bathke, C.G.; Wallace, R.K.; Hase, K.R.; Jarvinen, G.D.; Ireland, J.R.; Johnson, M.W.; Ebbinghaus, B.B.; Sleaford, B.W.; Robel, M.; Bradley, K.S.; Collins, B.A.; Prichard, A.W.; Smith, B.W.

    2010-01-01

    This paper examines the attractiveness of materials mixtures containing special nuclear materials (SNM) associated with the various processing steps required for a closed fuel cycle. This paper combines the results from earlier studies that examined the attractiveness of SNM associated with the processing of spent light water reactor (LWR) fuel by various reprocessing schemes and the recycle of plutonium as a mixed oxide (MOX) fuel in LWR with new results for the final, repeated burning of SNM in fast-spectrum reactors: fast reactors and accelerator driven systems (ADS). The results of this paper suggest that all reprocessing products evaluated so far need to be rigorously safeguarded and provided moderate to high levels of physical protection. These studies were performed at the request of the United States Department of Energy (DOE), and are based on the calculation of 'attractiveness levels' that has been couched in terms chosen for consistency with those normally used for nuclear materials in DOE nuclear facilities. The methodology and key findings will be presented. Additionally, how these attractiveness levels relate to proliferation resistance (e.g. by increasing impediments to the diversion, theft, or undeclared production of SNM for the purpose of acquiring a nuclear weapon), and how they could be used to help inform policy makers, will be discussed. (authors)

  20. Nuclear Material Attractiveness: An Assessment Of Material Associated With A Closed Fuel Cycle

    International Nuclear Information System (INIS)

    Bathke, C.G.; Ebbinghaus, B.; Sleaford, Brad W.; Wallace, R.K.; Collins, Brian A.; Hase, Kevin R.; Robel, Martin; Jarvinen, G.D.; Bradley, Keith S.; Ireland, J.R.; Johnson, M.W.; Prichard, Andrew W.; Smith, Brian W.

    2010-01-01

    This paper examines the attractiveness of materials mixtures containing special nuclear materials (SNM) associated with the various processing steps required for a closed fuel cycle. This paper combines the results from earlier studies that examined the attractiveness of SNM associated with the processing of spent light water reactor (LWR) fuel by various reprocessing schemes and the recycle of plutonium as a mixed oxide (MOX) fuel in LWR with new results for the final, repeated burning of SNM in fast-spectrum reactors: fast reactors and accelerator driven systems (ADS). The results of this paper suggest that all reprocessing products evaluated so far need to be rigorously safeguarded and provided moderate to high levels of physical protection. These studies were performed at the request of the United States Department of Energy (DOE), and are based on the calculation of 'attractiveness levels' that has been couched in terms chosen for consistency with those normally used for nuclear materials in DOE nuclear facilities. The methodology and key findings will be presented. Additionally, how these attractiveness levels relate to proliferation resistance (e.g. by increasing impediments to the diversion, theft, or undeclared production of SNM for the purpose of acquiring a nuclear weapon), and how they could be used to help inform policy makers, will be discussed.

  1. Valve Disease

    Science.gov (United States)

    ... blood. There are 4 valves in the heart: tricuspid, pulmonary, mitral, and aortic. Two types of problems can disrupt blood flow through the valves: regurgitation or stenosis. Regurgitation is also called insufficiency or incompetence. Regurgitation happens when a valve doesn’ ...

  2. A Practical Approach to a Closed Nuclear Fuel Cycle and Sustained Nuclear Energy - 12383

    Energy Technology Data Exchange (ETDEWEB)

    Collins, Emory D.; Del Cul, Guillermo D.; Spencer, Barry B.; Williams, Kent A. [Oak Ridge National Laboratory, P.O. Box 2008, MS-6152, Oak Ridge TN 37831 (United States)

    2012-07-01

    Recent systems analysis studies at Oak Ridge National Laboratory (ORNL) have shown that sufficient information is available from previous research and development (R and D), industrial experience, and current studies to make rational decisions on a practical approach to a closed nuclear fuel cycle in the United States. These studies show that a near-term decision is needed to recycle used nuclear fuel (UNF) in the United States, to encourage public recognition that a practical solution to disposal of nuclear energy wastes, primarily UNF, is achievable, and to ensure a focus on essential near-term actions and future R and D. Recognition of the importance of time factors is essential, including the multi-decade time period required to implement industrial-scale fuel recycle at the capacity needed, and the effects of radioactive decay on proliferation resistance, recycling complexity, radioactive emissions, and high-level-waste storage, disposal form development, and eventual emplacement in a geologic repository. Analysis of time factors led to identification of the benefits of processing older fuel and an 'optimum decay storage time'. Further benefits of focused R and D can ensure more complete recycling of UNF components and minimize wastes requiring disposal. Analysis of recycling costs and nonproliferation requirements, which are often cited as reasons for delaying a decision to recycle, shows that (1) the differences in costs of nuclear energy with open or closed fuel cycles are insignificant and (2) nonproliferation requirements can be met by a combination of 'safeguards-by-design' co-location of back-end fuel cycle facilities, and applied engineered safeguards and monitoring. The study shows why different methods of separating and recycling used fuel components do not have a significant effect on nonproliferation requirements and can be selected on other bases, such as process efficiency, maturity, and cost-effectiveness. Finally, the study

  3. A Practical Approach to a Closed Nuclear Fuel Cycle and Sustained Nuclear Energy - 12383

    Energy Technology Data Exchange (ETDEWEB)

    Collins, Emory D.; Del Cul, Guillermo D.; Spencer, Barry B.; Williams, Kent A. [Oak Ridge National Laboratory, P.O. Box 2008, MS-6152, Oak Ridge TN 37831 (United States)

    2012-07-01

    Recent systems analysis studies at Oak Ridge National Laboratory (ORNL) have shown that sufficient information is available from previous research and development (R and D), industrial experience, and current studies to make rational decisions on a practical approach to a closed nuclear fuel cycle in the United States. These studies show that a near-term decision is needed to recycle used nuclear fuel (UNF) in the United States, to encourage public recognition that a practical solution to disposal of nuclear energy wastes, primarily UNF, is achievable, and to ensure a focus on essential near-term actions and future R and D. Recognition of the importance of time factors is essential, including the multi-decade time period required to implement industrial-scale fuel recycle at the capacity needed, and the effects of radioactive decay on proliferation resistance, recycling complexity, radioactive emissions, and high-level-waste storage, disposal form development, and eventual emplacement in a geologic repository. Analysis of time factors led to identification of the benefits of processing older fuel and an 'optimum decay storage time'. Further benefits of focused R and D can ensure more complete recycling of UNF components and minimize wastes requiring disposal. Analysis of recycling costs and nonproliferation requirements, which are often cited as reasons for delaying a decision to recycle, shows that (1) the differences in costs of nuclear energy with open or closed fuel cycles are insignificant and (2) nonproliferation requirements can be met by a combination of 'safeguards-by-design' co-location of back-end fuel cycle facilities, and applied engineered safeguards and monitoring. The study shows why different methods of separating and recycling used fuel components do not have a significant effect on nonproliferation requirements and can be selected on other bases, such as process efficiency, maturity, and cost-effectiveness. Finally, the study concludes that

  4. Valve for gas centrifuges

    Science.gov (United States)

    Hahs, Charles A.; Burbage, Charles H.

    1984-01-01

    The invention is a pneumatically operated valve assembly for simultaneously (1) closing gas-transfer lines connected to a gas centrifuge or the like and (2) establishing a recycle path between two of the lines so closed. The valve assembly is especially designed to be compact, fast-acting, reliable, and comparatively inexpensive. It provides large reductions in capital costs for gas-centrifuge cascades.

  5. Variants of Regenerated Fissile Materials Usage in Thermal Reactors as the First Stage of Fuel Cycle Closing

    Science.gov (United States)

    Andrianova, E. A.; Tsibul'skiy, V. F.

    2017-12-01

    At present, 240 000 t of spent nuclear fuel (SF) has been accumulated in the world. Its long-term storage should meet safety conditions and requires noticeable finances, which grow every year. Obviously, this situation cannot exist for a long time; in the end, it will require a final decision. At present, several variants of solution of the problem of SF management are considered. Since most of the operating reactors and those under construction are thermal reactors, it is reasonable to assume that the structure of the nuclear power industry in the near and medium-term future will be unchanged, and it will be necessary to utilize plutonium in thermal reactors. In this study, different strategies of SF management are compared: open fuel cycle with long-term SF storage, closed fuel cycle with MOX fuel usage in thermal reactors and subsequent long-term storage of SF from MOX fuel, and closed fuel cycle in thermal reactors with heterogeneous fuel arrangement. The concept of heterogeneous fuel arrangement is considered in detail. While in the case of traditional fuel it is necessary to reprocess the whole amount of spent fuel, in the case of heterogeneous arrangement, it is possible to separate plutonium and 238U in different fuel rods. In this case, it is possible to achieve nearly complete burning of fissile isotopes of plutonium in fuel rods loaded with plutonium. These fuel rods with burned plutonium can be buried after cooling without reprocessing. They would contain just several percent of initially loaded plutonium, mainly even isotopes. Fuel rods with 238U alone should be reprocessed in the usual way.

  6. RIAR experimental base development concept 1. Multi-purpose pyrochemical complex for experimental justification of innovative closed fuel cycle technologies

    Energy Technology Data Exchange (ETDEWEB)

    Bychkov, A.V.; Kormilitsyn, M.V. [Research Institute of Atomic Reactors, Dimitrovgrad-10, Ulyanovsk region, 433510 (Russian Federation)

    2009-06-15

    The principles of closed FC arrangement on the basis of non-aqueous methods allow the development of production addressing two tasks simultaneously: production of fresh fuel and reprocessing of irradiated fuel, that makes it possible to achieve the industrial level of implementation of closed FC of fast reactors of new generation in a series variant of standardized process modules on the basis of innovative pyrochemical high-effective compact technologies. For the purpose of experimental justification of innovative closed FC technologies at the RIAR site, the existing experimental base is being updated and a multi-purpose pyrochemical complex is developed: - Experimental complex of pyrochemical molten salt facilities to reprocess all types of spent fuel (MOX, nitride, metallic, IMF) of fast reactors of new generation (BN-800, MBIR, BREST). - Experimental complex of facilities to master a gas-fluoride technology of reprocessing intractable fuel, research reactors fuel and thermal SNF. - Transition of the existing facility of pyro-electrochemical production of MOX fuel into the mode of reprocessing of the BN-800 MOX SNF. - Renovation of the facilities for production of fuel elements from experimental, re-fabricated, innovative and high-active fuel - a complex of heavy and glove boxes - to produce experimental fuel elements and targets with MAs on the basis of oxides (vibro and pellets), mixed nitrides, metal alloys and inert matrices in heavy boxes. - Upgrading of the complex for mastering and demonstration of the processes for radioactive waste management and spent fuel pyrochemical reprocessing. The report covers main concept and design solutions, plans and schedule of the program for development of pyrochemical complex for experimental justification of innovative closed FC technologies. (authors)

  7. Technology readiness of partitioning and transmutation toward closed fuel cycle in Japan

    International Nuclear Information System (INIS)

    Ikeda, Kazumi; Kurata, Masaki; Morita, Yasuji; Tsujimoto, Kazufumi; Minato, Kazuo; Koyama, Shin-ichi

    2011-01-01

    This paper treats technology readiness level (TRL) assessment of Partitioning and Transmutation (P-T) toward closed fuel cycle in JAPAN. The purpose is providing clarified information related to the current maturity of the partitioning and transmutation technologies by applying the methodology of TRL, parallel to attempting to establish common indications among relating technology area. The methodology should be one of useful communication tools between specialists and management level, and also among countries interested in the P-T technologies. The generic TRL in this study is based on the GNEP (Global Nuclear Energy Partnership)'s definition: TRL 3 shows the status that critical function is proved and elemental technologies are identified, TRL 4 represents that relating technologies are validated at bench scale in laboratory environment, and TRL 5 achieves the completion of development related to the subsystem and elemental technologies. Detailed indications are established through discussion of the relating specialists. Reviewed technological area includes P-T and minor actinide (MA) cycle: Fast Breeder Reactor (FBR) and Accelerator driven system (ADS) for MA transmutation, partitioning processes, and MA-bearing fuels. The assessments reveal that TRL spreads around TRL 3 to TRL 4 because each system requires more the development of elemental technologies. Transmutation core of FBR is assessed to be TRL 4 in that MA bearing integral test is required additionally, and ADS becomes TRL 3 because the elemental technologies were identified and the requirements were specified. Consequently, the common key issue is how the nuclear calculation methodology will be validated for MA-bearing-fuelled core, since several percentages of MA changes the void reactivity and the Doppler Effect significantly, which are inherently important in reactor safety. It should be that critical experiments with several kg of americium or more are difficult in the existing experimental

  8. BN800: The advanced sodium cooled fast reactor plant based on close fuel cycle

    International Nuclear Information System (INIS)

    Wu Xingman

    2011-01-01

    As one of the advanced countries with actually fastest reactor technology, Russia has always taken a leading role in the forefront of the development of fast reactor technology. After successful operation of BN600 fast reactor nuclear power station with a capacity of six hundred thousand kilowatts of electric power for nearly 30 years, and after a few decades of several design optimization improved and completed on its basis, it is finally decided to build Unit 4 of Beloyarsk nuclear power station (BN800 fast reactor power station). The BN800 fast reactor nuclear power station is considered to be the project of the world's most advanced fast reactor nuclear power being put into implementation. The fast reactor technology in China has been developed for decades. With the Chinese pilot fast reactor to be put into operation soon, the Chinese model fast reactor power station has been put on the agenda. Meanwhile, the closed fuel cycle development strategy with fast reactor as key aspect has given rise to the concern of experts and decision-making level in relevant areas. Based on the experiences accumulated in many years in dealing the Sino-Russian cooperation in fast reactor technology, with reference to the latest Russian published and authoritative literatures regarding BN800 fast reactor nuclear power station, the author compiled this article into a comprehensive introduction for reference by leaders and experts dealing in the related fields of nuclear fuel cycle strategy and fast reactor technology development researches, etc. (authors)

  9. Closing the gap between spent fuel storage and final disposal in a multinational management system

    International Nuclear Information System (INIS)

    Bredell, P.J.

    1999-01-01

    In this paper, a multinational spent fuel management concept is proposed. The management concept is based on a service agreement between countries, which intend participating in a common spent fuel (SNF) management venture. Accordingly, one of the participants in this venture would act as the hosting country, while the others fulfil the role of customer countries. The hosting country would agree to accept SNF from customer countries under specific conditions, as required by the service agreement. The service agreement should cover a sufficient number of options that customers can use, such as storage, reprocessing or disposal. The service offering should be flexible enough to accommodate diverse customer requirements. Typically, the first step in the multinational management process is the storage of the SNF delivered to the hosting country. The final step being the disposal of the material in a deep geologic repository. This paper explores the ways and means of closing the gap between the first and last steps in the management process. (author)

  10. Tight valve

    International Nuclear Information System (INIS)

    Guedj, F.

    1987-01-01

    This sealed valve is made with a valve seat, an axial valve with a rod fixed to its upper end, a thick bell surrounding the rod and welded by a thin join on the valve casing, a threated ring screwed onto the upper end of the rod and a magnet or electromagnet rotating the ring outside the bell [fr

  11. Liquid air fueled open-closed cycle Stirling engine and its exergy analysis

    International Nuclear Information System (INIS)

    Wang, Jia; Xu, Weiqing; Ding, Shuiting; Shi, Yan; Cai, Maolin; Rehman, Ali

    2015-01-01

    An unconventional Stirling engine is proposed and its theoretical analysis is performed. The engine belongs to a “cryogenic heat engine” that is fueled by cryogenic medium. Conventional “cryogenic heat engine” employs liquid air as a pressure source, but disregards its heat-absorbing ability. Therefore, its efficiency can only be improved by increasing vapor pressure, accordingly increasing the demand on pressure resistance and sealing. In the proposed engine, a closed cycle structure of Stirling engine is added to combine with the open cycle structure of a conventional cryogenic heat engine to achieve high efficiency and simplicity by utilizing the heat-absorbing ability of liquid air. Besides, the theoretical analysis of the proposed engine is performed. The Schmidt theory is modified to model temperature variation in the cold space of the engine, and irreversible characteristic of regenerator is incorporated in the thermodynamic model. The modeling results show that under the same working pressure, the efficiency of the proposed engine is potentially higher than that of conventional ones and to achieve the same efficiency, the working pressure could be lower with the new mechanism. Composition of exergy loss in the proposed engine is analyzed. - Highlights: • Cryogenic energy is better exploited by the open-closed cycle Stirling mechanism. • The Schmidt theory is modified to model temperature variation. • Irreversible characteristics are incorporated in the thermodynamic model. • Composition of exergy loss in proposed engine is analyzed.

  12. A shut-off valve for flexible tubing

    Science.gov (United States)

    Reyburn, W. W.

    1972-01-01

    Design of light weight valve for flexible tubing is described. Valve is hand operated and provides positive sealing in normally closed position. Diagram is provided to show construction of valve. Principles of operation are explained.

  13. Method of effecting fast turbine valving for improvement of power system stability

    International Nuclear Information System (INIS)

    Park, R.H.

    1981-01-01

    As a improved way of effecting fast valving of turbines of power system steam-electric generating units for the purpose of improving the stability of power transmission over transmission circuits to which their generators make connection, when stability is threatened by line faults and certain other stability endangering events, the heretofore employed and/or advocated practice of automatically closing intercept valves at fastest available closing speed in response to a fast valving signal, and thereafter automatically fully reopening them in a matter of seconds, is modified by providing to reopen the valves only partially to and thereafter retain them at a preset partially open position. For best results the process of what can be termed sustained partial reopening is so effected as to result in its completion within a fraction of a second following the peak of the first forward swing of the generator rotor. Control valves may be either held open, or automatically fully or partly closed and thereafter fully opened in a preprogrammed manner, or automatically moved to and thereafter held in a partly closed position, by means of a preprogrammed process of repositioning in which the valves may optionally be first fully or partly closed and thereafter partly reopened. Avoidance of discharge of steam through high pressure safety valves can be had with use of suitably controlled power operated valves that discharge steam to the condenser or to atmosphere. Where there is an intermediate pressure turbine that is supplied with superheated steam, use of sustained partial control valve closure, if employed, is supplemented by provision for reduction of rate of heat release within the steam generator in order to protect the reheater from overheating. As a way to restrict increase of reheat pressure of fossil fuel installations, and to minimize increase in the msr (Moisture separator-reheater) pressure of nuclear units, provision is optionally made of normally closed by-pass v

  14. Check valve

    Science.gov (United States)

    Upton, H.A.; Garcia, P.

    1999-08-24

    A check valve for use in a GDCS of a nuclear reactor and having a motor driven disk including a rotatable armature for rotating the check valve disk over its entire range of motion is described. In one embodiment, the check valve includes a valve body having a coolant flow channel extending therethrough. The coolant flow channel includes an inlet end and an outlet end. A valve body seat is located on an inner surface of the valve body. The check valve further includes a disk assembly, sometimes referred to as the motor driven disc, having a counterweight and a disk shaped valve. The disk valve includes a disk base having a seat for seating with the valve body seat. The disk assembly further includes a first hinge pin member which extends at least partially through the disk assembly and is engaged to the disk. The disk valve is rotatable relative to the first hinge pin member. The check valve also includes a motor having a stator frame with a stator bore therein. An armature is rotatably positioned within the stator bore and the armature is coupled to the disk valve to cause the disk valve to rotate about its full range of motion. 5 figs.

  15. Check valve

    International Nuclear Information System (INIS)

    Upton, H.A.; Garcia, P.

    1999-01-01

    A check valve for use in a GDCS of a nuclear reactor and having a motor driven disk including a rotatable armature for rotating the check valve disk over its entire range of motion is described. In one embodiment, the check valve includes a valve body having a coolant flow channel extending therethrough. The coolant flow channel includes an inlet end and an outlet end. A valve body seat is located on an inner surface of the valve body. The check valve further includes a disk assembly, sometimes referred to as the motor driven disc, having a counterweight and a disk shaped valve. The disk valve includes a disk base having a seat for seating with the valve body seat. The disk assembly further includes a first hinge pin member which extends at least partially through the disk assembly and is engaged to the disk. The disk valve is rotatable relative to the first hinge pin member. The check valve also includes a motor having a stator frame with a stator bore therein. An armature is rotatably positioned within the stator bore and the armature is coupled to the disk valve to cause the disk valve to rotate about its full range of motion. 5 figs

  16. An Improved Quantum-Behaved Particle Swarm Optimization Method for Economic Dispatch Problems with Multiple Fuel Options and Valve-Points Effects

    Directory of Open Access Journals (Sweden)

    Hong-Yun Zhang

    2012-09-01

    Full Text Available Quantum-behaved particle swarm optimization (QPSO is an efficient and powerful population-based optimization technique, which is inspired by the conventional particle swarm optimization (PSO and quantum mechanics theories. In this paper, an improved QPSO named SQPSO is proposed, which combines QPSO with a selective probability operator to solve the economic dispatch (ED problems with valve-point effects and multiple fuel options. To show the performance of the proposed SQPSO, it is tested on five standard benchmark functions and two ED benchmark problems, including a 40-unit ED problem with valve-point effects and a 10-unit ED problem with multiple fuel options. The results are compared with differential evolution (DE, particle swarm optimization (PSO and basic QPSO, as well as a number of other methods reported in the literature in terms of solution quality, convergence speed and robustness. The simulation results confirm that the proposed SQPSO is effective and reliable for both function optimization and ED problems.

  17. Coanda effect in valves

    Directory of Open Access Journals (Sweden)

    Uruba Václav

    2017-01-01

    Full Text Available Coanda effect takes place in flow within valves diffuser for certain conditions. The valve plug in half-closed position forms wall-jet, which could be stable or instable, depending on geometry and other conditions. This phenomenon was subject of experimental study using time-resolved PIV technique. For the acquired data analysis the special spatio-temporal methods have been used.

  18. Nuclear reactor steam depressurization valve

    International Nuclear Information System (INIS)

    Moore, G.L.

    1991-01-01

    This patent describes improvement in a nuclear reactor plant, an improved steam depressurization valve positioned intermediate along a steam discharge pipe for controlling the venting of steam pressure from the reactor through the pipe. The improvement comprises: a housing including a domed cover forming a chamber and having a partition plate dividing the chamber into a fluid pressure activation compartment and a steam flow control compartment, the valve housing being provided with an inlet connection and an outlet connection in the steam flow control compartment, and a fluid duct in communication with a source of fluid pressure for operating the valve; a valve set mounted within the fluid flow control compartment comprising a cylindrical section surrounding the inlet connection with one end adjoining the connection and having a radially projecting flange at the other end with a contoured extended valve sealing flange provided with an annular valve sealing member, and a valve cylinder traversing the partition plate and reciprocally movable within an opening in the partition plate with one terminal and extending into the fluid pressure activation compartment and the other terminal end extending into the steam flow control compartment coaxially aligned with the valve seat surrounding the inlet connection, the valve cylinder being surrounded by two bellow fluid seals and provided with guides to inhibit lateral movement, an end of the valve cylinder extending into the fluid flow control compartment having a radially projecting flange substantially conterminous with the valve seat flange and having a contoured surface facing and complimentary to the contoured valve seating surface whereby the two contoured valve surfaces can meet in matching relationship, thus providing a pressure actuated reciprocatable valve member for making closing contact with the valve seat and withdrawing therefrom for opening fluid flow through the valve

  19. Assessment of Proliferation Resistance of Closed Nuclear Fuel Cycle System with Sodium Cooled Fast Reactors Using INPRO Evaluation Methodology

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young In; Hahn, Do Hee; Won, Byung Chool; Lee, Dong Uk

    2007-11-15

    Using the INPRO methodology, the proliferation resistance of an innovative nuclear energy system(INS) defined as a closed nuclear fuel cycle system consisting of KALIMER and pyroprocessing, has been assessed. Considering a very early development stage of the INS concept, the PR assessment is carried out based on intrinsic features, if required information and data are not available. The PR assessment of KALIMER and JSFR using the INPRO methodology affirmed that an adequate proliferation resistance has been achieved in both INSs CNFC-SFR, considering the assessor's progress and maturity of design development. KALIMER and JSFR are developed or being developed conforming to the targets and criteria defined for developing Gen IV nuclear reactor system. Based on these assessment results, proliferation resistance and physical protection(PR and PP) of KALIMER and JSFR are evaluated from the viewpoint of requirements for future nuclear fuel cycle system. The envisioned INSs CNFC-SFR rely on active plutonium management based on a closed fuel cycle, in which a fissile material is recycled in an integrated fuel cycle facility within proper safeguards. There is no isolated plutonium in the closed fuel cycle. The material remains continuously in a sequence of highly radioactive matrices within inaccessible facilities. The proliferation resistance assessment should be an ongoing analysis that keeps up with the progress and maturity of the design of Gen IV SFR.

  20. Assessment of Proliferation Resistance of Closed Nuclear Fuel Cycle System with Sodium Cooled Fast Reactors Using INPRO Evaluation Methodology

    International Nuclear Information System (INIS)

    Kim, Young In; Hahn, Do Hee; Won, Byung Chool; Lee, Dong Uk

    2007-11-01

    Using the INPRO methodology, the proliferation resistance of an innovative nuclear energy system(INS) defined as a closed nuclear fuel cycle system consisting of KALIMER and pyroprocessing, has been assessed. Considering a very early development stage of the INS concept, the PR assessment is carried out based on intrinsic features, if required information and data are not available. The PR assessment of KALIMER and JSFR using the INPRO methodology affirmed that an adequate proliferation resistance has been achieved in both INSs CNFC-SFR, considering the assessor's progress and maturity of design development. KALIMER and JSFR are developed or being developed conforming to the targets and criteria defined for developing Gen IV nuclear reactor system. Based on these assessment results, proliferation resistance and physical protection(PR and PP) of KALIMER and JSFR are evaluated from the viewpoint of requirements for future nuclear fuel cycle system. The envisioned INSs CNFC-SFR rely on active plutonium management based on a closed fuel cycle, in which a fissile material is recycled in an integrated fuel cycle facility within proper safeguards. There is no isolated plutonium in the closed fuel cycle. The material remains continuously in a sequence of highly radioactive matrices within inaccessible facilities. The proliferation resistance assessment should be an ongoing analysis that keeps up with the progress and maturity of the design of Gen IV SFR

  1. Current collector design for closed-plenum polymer electrolyte membrane fuel cells

    Science.gov (United States)

    Daniels, F. A.; Attingre, C.; Kucernak, A. R.; Brett, D. J. L.

    2014-03-01

    This work presents a non-isothermal, single-phase, three-dimensional model of the effects of current collector geometry in a 5 cm2 closed-plenum polymer electrolyte membrane (PEM) fuel cell constructed using printed circuit boards (PCBs). Two geometries were considered in this study: parallel slot and circular hole designs. A computational fluid dynamics (CFD) package was used to account for species, momentum, charge and membrane water distribution within the cell for each design. The model shows that the cell can reach high current densities in the range of 0.8 A cm-2-1.2 A cm-2 at 0.45 V for both designs. The results indicate that the transport phenomena are significantly governed by the flow field plate design. A sensitivity analysis on the channel opening ratio shows that the parallel slot design with a 50% opening ratio shows the most promising performance due to better species, heat and charge distribution. Modelling and experimental analysis confirm that flooding inhibits performance, but the risk can be minimised by reducing the relative humidity of the cathode feed to 50%. Moreover, overheating is a potential problem due to the insulating effect of the PCB base layer and as such strategies should be implemented to combat its adverse effects.

  2. Multiple recycling of fuel in prototype fast breeder reactor in a closed ...

    Indian Academy of Sciences (India)

    Our previous study in this regard for the prototype fast breeder reactor ... This study aims at finding the feasibility of multiple recycling of PFBR fuel with external ...... maximum allowable Pu content in fuel based on chemistry/metallurgical ...

  3. Control Valve

    Energy Technology Data Exchange (ETDEWEB)

    Moore, Wayne R.

    2018-03-20

    A control valve includes a first conduit having a first inlet and a first outlet and defining a first passage; a second conduit having a second inlet and a second outlet and defining a second passage, the second conduit extending into the first passage such that the second inlet is located within the first passage; and a valve plate disposed pivotably within the first passage, the valve plate defining a valve plate surface. Pivoting of the valve plate within the first passage varies flow from the first inlet to the first outlet and the valve plate is pivotal between a first position and a second position such that in the first position the valve plate substantially prevents fluid communication between the first passage and the second passage and such that in the second position the valve plate permits fluid communication between the first passage and the second passage.

  4. Nuclear fuel cycle, nuclear fuel makes the rounds: choosing a closed fuel cycle, nuclear fuel cycle processes, front-end of the fuel cycle: from crude ore to enriched uranium, back-end of the fuel cycle: the second life of nuclear fuel, and tomorrow: multiple recycling while generating increasingly less waste

    International Nuclear Information System (INIS)

    Philippon, Patrick

    2016-01-01

    France has opted for a policy of processing and recycling spent fuel. This option has already been deployed commercially since the 1990's, but will reach its full potential with the fourth generation. The CEA developed the processes in use today, and is pursuing research to improve, extend, and adapt these technologies to tomorrow's challenges. France has opted for a 'closed cycle' to recycle the reusable materials in spent fuel (uranium and plutonium) and optimise ultimate waste management. France has opted for a 'closed' nuclear fuel cycle. Spent fuel is processed to recover the reusable materials: uranium and plutonium. The remaining components (fission products and minor actinides) are the ultimate waste. This info-graphic shows the main steps in the fuel cycle currently implemented commercially in France. From the mine to the reactor, a vast industrial system ensures the conversion of uranium contained in the ore to obtain uranium oxide (UOX) fuel pellets. Selective extraction, purification, enrichment - key scientific and technical challenges for the teams in the Nuclear Energy Division (DEN). The back-end stages of the fuel cycle for recycling the reusable materials in spent fuel and conditioning the final waste-forms have reached maturity. CEA teams are pursuing their research in support of industry to optimise these processes. Multi-recycle plutonium, make even better use of uranium resources and, over the longer term, explore the possibility of transmuting the most highly radioactive waste: these are the challenges facing future nuclear systems. (authors)

  5. Valve assembly

    International Nuclear Information System (INIS)

    Sandling, M.

    1981-01-01

    An improved valve assembly, used for controlling the flow of radioactive slurry, is described. Radioactive contamination of the air during removal or replacement of the valve is prevented by sucking air from the atmosphere through a portion of the structure above the valve housing. (U.K.)

  6. Hydraulic engine valve actuation system including independent feedback control

    Science.gov (United States)

    Marriott, Craig D

    2013-06-04

    A hydraulic valve actuation assembly may include a housing, a piston, a supply control valve, a closing control valve, and an opening control valve. The housing may define a first fluid chamber, a second fluid chamber, and a third fluid chamber. The piston may be axially secured to an engine valve and located within the first, second and third fluid chambers. The supply control valve may control a hydraulic fluid supply to the piston. The closing control valve may be located between the supply control valve and the second fluid chamber and may control fluid flow from the second fluid chamber to the supply control valve. The opening control valve may be located between the supply control valve and the second fluid chamber and may control fluid flow from the supply control valve to the second fluid chamber.

  7. Natural Transmutation of Actinides via the Fission Reaction in the Closed Thorium-Uranium-Plutonium Fuel Cycle

    Science.gov (United States)

    Marshalkin, V. Ye.; Povyshev, V. M.

    2017-12-01

    It is shown for a closed thorium-uranium-plutonium fuel cycle that, upon processing of one metric ton of irradiated fuel after each four-year campaign, the radioactive wastes contain 54 kg of fission products, 0.8 kg of thorium, 0.10 kg of uranium isotopes, 0.005 kg of plutonium isotopes, 0.002 kg of neptunium, and "trace" amounts of americium and curium isotopes. This qualitatively simplifies the handling of high-level wastes in nuclear power engineering.

  8. All heavy metals closed-cycle analysis on water-cooled reactors of uranium and thorium fuel cycle systems

    International Nuclear Information System (INIS)

    Permana, Sidik; Sekimoto, Hiroshi; Waris, Abdul; Takaki, Naoyuki

    2009-01-01

    Uranium and Thorium fuels as the basis fuel of nuclear energy utilization has been used for several reactor types which produce trans-uranium or trans-thorium as 'by product' nuclear reaction with higher mass number and the remaining uranium and thorium fuels. The utilization of recycled spent fuel as world wide concerns are spent fuel of uranium and plutonium and in some cases using recycled minor actinide (MA). Those fuel schemes are used for improving an optimum nuclear fuel utilization as well to reduce the radioactive waste from spent fuels. A closed-cycle analysis of all heavy metals on water-cooled cases for both uranium and thorium fuel cycles has been investigated to evaluate the criticality condition, breeding performances, uranium or thorium utilization capability and void reactivity condition. Water-cooled reactor is used for the basic design study including light water and heavy water-cooled as an established technology as well as commercialized nuclear technologies. A developed coupling code of equilibrium fuel cycle burnup code and cell calculation of SRAC code are used for optimization analysis with JENDL 3.3 as nuclear data library. An equilibrium burnup calculation is adopted for estimating an equilibrium state condition of nuclide composition and cell calculation is performed for calculating microscopic neutron cross-sections and fluxes in relation to the effect of different fuel compositions, different fuel pin types and moderation ratios. The sensitivity analysis such as criticality, breeding performance, and void reactivity are strongly depends on moderation ratio and each fuel case has its trend as a function of moderation ratio. Heavy water coolant shows better breeding performance compared with light water coolant, however, it obtains less negative or more positive void reactivity. Equilibrium nuclide compositions are also evaluated to show the production of main nuclides and also to analyze the isotopic composition pattern especially

  9. DISCHARGE VALVE FOR GRANULAR MATERIAL

    Science.gov (United States)

    Stoughton, L.D.; Robinson, S.T.

    1962-05-15

    A gravity-red dispenser or valve is designed for discharging the fueled spherical elements used in a pebble bed reactor. The dispenser consists of an axially movable tube terminating under a hood having side walls with openings. When the tube is moved so that its top edge is above the tops of the side openings the elements will not flow. As the tube is moved downwardly, the elements flow into the hood through the side openings and over the top edge into the tube at an increasing rate as the tube is lowered further. The tube is spaced at all times from the hood and side walls a distance greater than the diameter of the largest element to prevent damaging of the elements when the dispenser is closed to flow. (AEC)

  10. Digital Simulation of Closed Loop Zvs-Zcs Bidirectional Dc-Dc Converter for Fuel Cell and Battery Application

    Directory of Open Access Journals (Sweden)

    V. V. Subrahmanya Kumar Bhajana

    2010-08-01

    Full Text Available A closed loop ZVS-ZCS bidirectional dc-dc converter is modeled and appropriate digital simulations are provided. With the ZVS-ZCS concept, the MATLAB simulation results of application to a fuel cell and battery application have been obtained whenever the input voltage exceeds the given 24V, at that time the load voltage will change from 180V to 230V. But due to this usage the load is disturbed and there is instability in the model. Using closed loop the output voltage is stabilized.

  11. Closed-Cycle Hydrogen-Oxygen Regenerative Fuel Cell at the NASA Glenn Research Center-An Update

    Science.gov (United States)

    Bents, David J.; Chang, Bei-Jiann; Johnson, Donald W.; Garcia, Christopher P.

    2008-01-01

    The closed cycle hydrogen-oxygen proton exchange membrane (PEM) regenerative fuel cell (RFC) at the NASA Glenn Research Center has demonstrated multiple back-to-back contiguous cycles at rated power and round-trip efficiencies up to 52 percent. It is the first fully closed cycle RFC ever demonstrated. (The entire system is sealed; nothing enters or escapes the system other than electrical power and heat.) During fiscal year fiscal year (FY) FY06 to FY07, the system s numerous modifications and internal improvements focused on reducing parasitic power, heat loss, and noise signature; increasing its functionality as an unattended automated energy storage device; and in-service reliability.

  12. Latest design of gate valves

    Energy Technology Data Exchange (ETDEWEB)

    Kurzhofer, U.; Stolte, J.; Weyand, M.

    1996-12-01

    Babcock Sempell, one of the most important valve manufacturers in Europe, has delivered valves for the nuclear power industry since the beginning of the peaceful application of nuclear power in the 1960s. The latest innovation by Babcock Sempell is a gate valve that meets all recent technical requirements of the nuclear power technology. At the moment in the United States, Germany, Sweden, and many other countries, motor-operated gate and globe valves are judged very critically. Besides the absolute control of the so-called {open_quotes}trip failure,{close_quotes} the integrity of all valve parts submitted to operational forces must be maintained. In case of failure of the limit and torque switches, all valve designs have been tested with respect to the quality of guidance of the gate. The guidances (i.e., guides) shall avoid a tilting of the gate during the closing procedure. The gate valve newly designed by Babcock Sempell fulfills all these characteristic criteria. In addition, the valve has cobalt-free seat hardfacing, the suitability of which has been proven by friction tests as well as full-scale blowdown tests at the GAP of Siemens in Karlstein, West Germany. Babcock Sempell was to deliver more than 30 gate valves of this type for 5 Swedish nuclear power stations by autumn 1995. In the presentation, the author will report on the testing performed, qualifications, and sizing criteria which led to the new technical design.

  13. Perspectives on the closed fuel cycle - Implications for high-level waste matrices

    International Nuclear Information System (INIS)

    Gras, Jean-Marie; Quang, Richard Do; Masson, Herve; Lieven, Thierry; Ferry, Cecile; Poinssot, Christophe; Debes, Michel; Delbecq, Jean-Michel

    2007-01-01

    Nuclear energy accounts for 80% of electricity production in France, generating approximately 1150 t of spent fuel for an electrical output of 420 TWh. Based on a reprocessing-conditioning-recycling strategy, the orientations taken by Electricite de France (EDF) for the mid-term and the far-future are to keep the fleet performances at the highest level, and to maintain the nuclear option fully open by the replacement of present pressurized water reactor (PWR) by new light water reactor (LWR), such as the evolutionary pressurized reactor (EPR) and future Generation IV designs. Adaptations of waste materials to new requirements will come with these orientations in order to meet long-term energy sustainability. In particular, waste materials and spent fuels are expected to meet increased requirements in comparison with the present situation. So the treatment of higher burn-up UO 2 spent fuel and MOX fuel requires determining the performances of glass and other matrices according to several criteria: chemical 'digestibility' (i.e. capacity of glass to incorporate fission products and minor actinides without loss of quality), resistance to alpha self-irradiation, residual power in view of disposal. Considering the long-term evolution of spent MOX fuel in storage, the helium production, the influence of irradiation damages accumulation and the evolution of the microstructure of the fuel pellet need to be known, as well as for the future fuels. Further, the eventual transmutation of minor actinides in fast neutron reactors (FR) of Generation IV, if its interest in optimising high-level waste management is proven, may also raise new challenges about the materials and fuel design. Some major questions in terms of waste materials and spent fuel are discussed in this paper

  14. Closed ThUOX Fuel Cycle for LWRs with ADTT (ATW) Backend for the 21st Century

    International Nuclear Information System (INIS)

    Beller, D.E.; Sailor, W.C.; Venneri, F.

    1998-01-01

    A future nuclear energy scenario with a closed, thorium-uranium-oxide (ThUOX) fuel cycle and new light water reactors (TULWRs) supported by Accelerator Transmutation of Waste (ATW) systems could provide several improvements beyond today's once-through, UO 2 -fueled nuclear technology. A deployment scenario with TULWRs plus ATWs to burn the actinides produced by these LWRs and to close the back-end of the ThUOX fuel cycle was modeled to satisfy a US demand that increases linearly from 80 GWe in 2020 to 200 GWe by 2100. During the first 20 years of the scenario (2000-2020), nuclear energy production in the US declines from today's 100 GWe to about 80 GWe, in accordance with forecasts of the US DOE's Energy Information Administration. No new nuclear systems are added during this declining nuclear energy period, and all existing LWRs are shut down by 2045. Beginning in 2020, ATWs that transmute the actinides from existing LWRs are deployed, along with TULWRs and additional ATWs with a support ratio of 1 ATW to 7 TULWRs to meet the energy demand scenario. A final mix of 174 GWe from TULWRs and 26 GWe from ATWs provides the 200 GWe demand in 2100. Compared to a once-through LWR scenario that meets the same energy demand, the TULWR/ATW concept could result in the following improvements: depletion of natural uranium resources would be reduced by 50%; inventories of Pu which may result in weapons proliferation will be reduced in quantity by more than 98% and in quality because of higher neutron emissions and 50 times the alpha-decay heating of weapons-grade plutonium; actinides (and possibly fission products) for final disposal in nuclear waste would be substantially reduced; and the cost of fuel and the fuel cycle may be 20-30% less than the once-through UO 2 fuel cycle

  15. Convincing about the advanced use of nuclear energy closing the fuel cycle: from a burden to a solution

    International Nuclear Information System (INIS)

    Neau, Henry Jacques

    2007-01-01

    France has associated a closed fuel cycle with its nuclear program, and developed the corresponding treatment recycling capabilities accordingly. This choice was recently consolidated by law. according to the sustainable management of radioactive materials and waste act of June 2006, the volume and radio toxicity reduction of nuclear waste is an objective that can notably be reached with their treatment and conditioning. Presently, used fuel valuable components (U and Pu) are recycled into MOX fuel and RepU, when fission products are conditioned under an extremely solid and resistant form which cannot disperse and dissolve in the environment (High Level Vitrified Waste). Safety and waste minimisation remain the AREVA constant objective. Presently operated treatment and recycling AREVA NC facilities are using mature industrial technologies, which address environment preservation and non proliferation concerns. This french national choice requires a permanent global acceptance strategy towards politicians, media, associations and more generally public opinion: to. be accepted, in needs to be understood. Transparency, dialogue and information are keywords for AREVA NC to be sure that closing the fuel cycle is considered as the best option available now for responsibly managing the waste, respecting the environment, preserving the resource and securing the future. Partnering in this Global Acceptance policy with other countries and customers, who already rely- or plan to do so - on this recycling strategy is both a reality and a permanent axis of development for AREVA NC

  16. Some conditions and prospects of going to a closed fuel cycle in Russia

    International Nuclear Information System (INIS)

    Lependin, A.V.; Oussanov, V.; Lependina, E.V.

    2000-01-01

    Nuclear policy in Russia is based on the necessity of closure of the nuclear fuel cycle. At the same time, the schedule of such a move is not yet defined. In this study, some conditions and possible time frames of taking the nuclear fuel cycle of Russia to closure are discussed. Naturally, the main condition is the revival of the Russian economy wherein nuclear power will turn out to be necessary in a number of Russian regions. The question is whether the closure of nuclear cycle strategy will be implemented in the near future or nuclear power will develop based on the open fuel cycle over a long period of time? (authors)

  17. Effects of the blockage ratio of a valve disk on loss coefficient in a butterfly valve

    International Nuclear Information System (INIS)

    Rho, Hyung Joon; Lee, Jee Keun; Choi, Hee Joo

    2008-01-01

    The loss coefficient of the butterfly valve which allows partial opening of the valve at closed position and is applicable to the small-sized pipe system with the diameter of 1 inch was measured for the variation of the valve disk blockage ratio. Two different types of the valve disk configuration to adjust the blockage ratio were considered. One was the solid type valve disk of which the diameter was changed into the smaller size rather than the pipe diameter, and the other was the perforate type valve disk on which some holes were perforated. The results from two types of valve disk were compared to identify their characteristics in the loss coefficient distributions. The loss coefficient and the controllable angle of the valve disk were decreased exponentially with the decrease of the blockage ratio. In addition, the perforate valve disk had the effect on the higher loss coefficient rather than the solid type valve disk

  18. Idling operation apparatus for multicylinder fuel injection engine

    Energy Technology Data Exchange (ETDEWEB)

    Kanahira, A

    1974-11-20

    A device to cut off the fuel supply to a number of cylinders at idling is described for those engines equipped with multicylinder fuel injection systems. The discontinuation of the fuel gas supply to the cylinders is made by a magnetically operated valve which is related to the accelerator. When the engine is idling, a switch activates the magnetic valve and the tube leading to the cylinder closes while a valve on the tube leading to a dual tank opens, and the pumped gas returns to the tank. This valve is installed on several cylinders, but not on all. Thus, at idling only a certain number of cylinders are firing, which lowers the hydrocarbon levels in the exhaust gas since non-firing cylinders intake and discharge only air.

  19. Mitral Valve Disease

    Science.gov (United States)

    ... for mitral valve replacement—mechanical valves (metal) or biological valves (tissue). The principal advantage of mechanical valves ... small risk of stroke due to blood clotting. Biological valves usually are made from animal tissue. Biological ...

  20. Prospects of subcritical molten salt reactor for minor actinides incineration in closed fuel cycle

    Energy Technology Data Exchange (ETDEWEB)

    Alekseev, Pavel N.; Balanin, Andrey L.; Dudnikov, Anatoly A.; Fomichenko, Petr A.; Nevinitsa, Vladimir A.; Frolov, Aleksey A.; Lubina, Anna S.; Sedov, Aleksey A.; Subbotin, Aleksey S.; Blandinsky, Viktor Yu. [Nuclear Research Centre ' ' Kurchatov Institute' ' , Moscow (Russian Federation)

    2015-09-15

    A subcritical molten salt reactor is proposed for minor actinides (separated from spent fuel VVER-1000 light water reactor) incineration and for {sup 233}U conversion from {sup 232}Th. Here the subcritical molten salt reactor with fuel composition of heavy nuclide fluorides in molten LiF - NaF - KF salt and with external neutron source, based on 1 GeV proton accelerator and molten salt cooled tungsten target is considered. The paper presents the results of parametrical analysis of equilibrium nuclide composition of molten salt reactor with minor actinides feed in dependence of core dimensions, average neutron flux and external neutron source intensity. Reactor design is defined; requirements to external neutron source are posed; heavy nuclides equilibrium and fuel cycle main parameters are calculated.

  1. Spring valve for well completion

    Energy Technology Data Exchange (ETDEWEB)

    Gorbatov, P T

    1966-07-22

    A spring-loaded valve for well completion consists of a housing with a spring-loaded closing element. In order to protect the closing element from corrosion which might lower the pressure drop, the closing element is made in the form of a piston. It is tightly connected with sealing elements. The housing has orifices, overlapping the piston in the initial position.

  2. Closed-form solution of a two-dimensional fuel temperature model for TRIGA-type reactors

    Energy Technology Data Exchange (ETDEWEB)

    Rivard, J B [Sandia Laboratories (United States)

    1974-07-01

    If azimuthal power density variations are ignored, the steady-state temperature distribution within a TRIGA-type fuel element is given by the solution of the Poisson equation in two dimensions (r and z) . This paper presents a closed-form solution of this equation as a function of the axial and radial power density profiles, the conductivity of the U-ZrH, the inlet temperature, specific heat and flow rate of the coolant, and the overall heat transfer coefficient. The method begins with the development of a system of linear ordinary differential equations describing mass and energy balances in the fuel and coolant. From the solution of this system, an expression for the second derivative of the fuel temperature distribution in the axial (z) direction is found. Substitution of this expression into the Poisson equation for T(r,z) reduces it from a partial differential equation to an ordinary differential equation in r, which is subsequently solved in closed-form. The results of typical calculations using the model are presented. (author)

  3. Nuclear power technology system with molten salt reactor for transuranium nuclides burning in closed fuel cycle

    International Nuclear Information System (INIS)

    Alekseev, P.N.; Dudnikov, A.A.; Ignatiev, V.V.; Prusakov, V.N.; Ponomarev-Stepnoy, N.N.; Subbotin, S.A.

    2000-01-01

    A concept of nuclear power technology system with homogeneous molten salt reactors for burning and transmutation of long-lived radioactive toxic nuclides is considered in the paper. Disposition of such reactors in enterprises of fuel cycle allows to provide them with power and facilitate solution of problems with rad waste with minimal losses. (Authors)

  4. Double-disc gate valve

    International Nuclear Information System (INIS)

    Wheatley, S.J.

    1979-01-01

    The invention relates to an improvement in a conventional double-disc gate valve having a vertically movable gate assembly including a wedge, spreaders slidably engaged therewith, a valve disc carried by the spreaders. When the gate assembly is lowered to a selected point in the valve casing, the valve discs are moved transversely outward to close inlet and outlet ports in the casing. The valve includes hold-down means for guiding the disc-and-spreader assemblies as they are moved transversely outward and inward. If such valves are operated at relatively high differential pressures, they sometimes jam during opening. Such jamming has been a problem for many years in gate valves used in gaseous diffusion plants for the separation of uranium isotopes. The invention is based on the finding that the above-mentioned jamming results when the outlet disc tilts about its horizontal axis in a certain way during opening of the valve. In accordance with the invention, tilting of the outlet disc is maintained at a tolerable value by providing the disc with a rigid downwardly extending member and by providing the casing with a stop for limiting inward arcuate movement of the member to a preselected value during opening of the valve

  5. Status of sodium cooled fast reactors with closed fuel cycle in India

    International Nuclear Information System (INIS)

    Raj, B.

    2007-01-01

    Fast reactors form the second stage of India's 3-stage nuclear power programme. The seed for India's fast reactor programme was sown through the construction of the Fast Breeder Test Reactor (FBTR) at IGCAR, Kalpakkam, that was commissioned in 1985. FBTR has operated with an unique, indigenously developed plutonium rich mixed carbide fuel, which has reached a burn up as high as 155 GWd/t without any fuel failure in the core. The sodium systems in the reactor have performed excellently. The availability of the reactor has been as high as 92% in the recent campaigns. The fuel discharged from FBTR up to 100 GWd/t has been reprocessed successfully. The experience gained in the construction, commissioning and operation of FBTR has provided the necessary confidence to launch a Prototype FBR of 500 MWe capacity (PFBR). This reactor will be fuelled by uranium, plutonium mixed oxide. The reactor construction started in 2003 and the reactor is scheduled to be commissioned by 2010. The design of the reactor has incorporated the worldwide operating experience from the FBRs and has addressed various safety issues reported in literature, besides introducing a number of innovative features which have reduced the unit energy cost and contributed to its enhanced safety. Simultaneous with the construction of the reactor, the fuel cycle of the reactor has been addressed in a comprehensive manner and construction of a fuel cycle facility has been initiated. Subsequent to the PFBR, 4 more reactors with identical design are proposed to be constructed. Various elements of reactor design are being carefully analysed with the aim of introducing innovative features towards further reduction in unit energy cost and enhancing safety in these reactors

  6. Rates of fuel discharge as affected by the design of fuel-injection systems for internal-combustion engines

    Science.gov (United States)

    Gelalles, A G; Marsh, E T

    1933-01-01

    Using the method of weighing fuel collected in a receiver during a definite interval of the injection period, rates of discharge were determined, and the effects noted, when various changes were made in a fuel-injection system. The injection system consisted primarily of a by-pass controlled fuel pump and an automatic injection valve. The variables of the system studied were the pump speed, pump-throttle setting, discharge-orifice diameter, injection-valve opening and closing pressures, and injection-tube length and diameter.

  7. Improved valve and dash-pot assembly

    Science.gov (United States)

    Chang, S.C.

    1985-04-23

    A dash-pot valve comprises a cylinder submerged in the fluid of a housing and have a piston attached to a plunger projecting into the path of closing movement of a pivotal valve member. A vortex chamber in said cylinder is provided with targentially directed inlets to generate vortex flow upon retraction of said plunger and effect increasing resistance against said piston to progressively retard the closing rate of said valve member toward its seat.

  8. Valve and dash-pot assembly

    Science.gov (United States)

    Chang, Shih-Chih

    1986-01-01

    A dash-pot valve comprising a cylinder submerged in the fluid of a housing and having a piston attached to a plunger projecting into the path of closing movement of a pivotal valve member. A vortex chamber in said cylinder is provided with tangentially directed inlets to generate vortex flow upon retraction of said plunger and effect increasing resistance against said piston to progressively retard the closing rate of said valve member toward its seat.

  9. Safety valve including a hydraulic brake and hydraulic brake that could be fitted into a valve

    International Nuclear Information System (INIS)

    Chabat-Courrede, Jean.

    1981-01-01

    Making of a safety valve that can be fitted to a containment vessel filled with a non compressible fluid, such as the water system of a nuclear power station. It includes a hydraulic brake located between the valve and the elastic means, close to the valve which completely suppresses the high frequency oscillations of the equipment [fr

  10. Closing the nuclear fuel cycle in the U.S., economics and business models

    International Nuclear Information System (INIS)

    Ratti, Stefano; Hanson, Alan; Shakir, Sam; Louvet, Thibault

    2007-01-01

    There are different strategies available for managing used nuclear fuel. Some countries recycle used fuel to re-utilize valuable material, while others store used fuel for future disposal in geologic repositories ('once-through' fuel cycle). For the last twenty years, the U.S. has adopted the once-through cycle and has begun the development of a geologic repository for used fuel disposal at Yucca Mountain. Several factors have emerged in the last few years and have started to re-open the debate on what is the appropriate used fuel management strategy in the U.S. Most notably, cost estimates for the development of a geologic repository have escalated and are expected to keep increasing in the near future. At the same time, the U.S. is seeing a renewed interest in nuclear energy and significant nuclear power generation capacity is expected to be added to the current base. Moreover, price of uranium have experience a dramatic rise, as much as a seven-fold increase, in the last two years. Finally, the recycling strategy has proven to be operationally effective in countries other than the U.S. and a solid industrial experience base has accumulated. Recycling as part of a comprehensive nuclear waste management strategy and complementary to an exclusive once-through strategy appear to be a viable option that requires serious consideration. Several questions need to be addressed to determine the viability of recycling in the U.S. What are the underlying economics and how does recycling compare with alternative options? What approach for technology and funding has the highest success rate for such a capital-intensive project? What kind of infrastructure (recycling plant, transportation, process, etc.) is needed? What is the most appropriate development schedule? Several scenarios have been evaluated through economic modeling and analyses of system dynamics. Results indicate that a recycling approach that includes a commercially-developed integrated recycling facility

  11. Water hammer caused by closure of turbine safety spherical valves

    Science.gov (United States)

    Karadžić, U.; Bergant, A.; Vukoslavčević, P.

    2010-08-01

    This paper investigates water hammer effects caused by closure of spherical valves against the discharge. During the first phase of modernisation of Perućica high-head hydropower plant (HPP), Montenegro, safety spherical valves (inlet turbine valves) have been refurbished on the first two Pelton turbine units. The valve closure is controlled by the valve actuator (hydraulic servomotor). Because the torque acting on the valve body is dependent on flow conditions the valve closing time may vary significantly for different flow velocities (passive valve). For the passive valve the torques acting on the valve body should be considered in the valve model. The valve closing time results from numerical simulation. On the contrary, for the active valve the valve closing time is assumed prior to simulation. The spherical valve boundary condition is incorporated into the method of characteristics (MOC) algorithm. The staggered (diamond) grid in applying the MOC is used in this paper. The passive valve boundary condition is described by the water hammer equations, the valve equation that relates discharge to pressure head drop and the dynamic equation of the valve body motion (torque equation). The active valve boundary condition is described by the first two equations, respectively. Standard quasi-steady friction model is used for estimating friction losses in plant's tunnel and penstocks. Numerical results using both the active and the passive spherical valve models are compared with results of measurements. It has been found that the influence of flow conditions on the spherical valve closing time is minor for the cases considered. Computed and measured results agree reasonably well.

  12. Water hammer caused by closure of turbine safety spherical valves

    International Nuclear Information System (INIS)

    Karadzic, U; Vukoslavcevic, P; Bergant, A

    2010-01-01

    This paper investigates water hammer effects caused by closure of spherical valves against the discharge. During the first phase of modernisation of Perucica high-head hydropower plant (HPP), Montenegro, safety spherical valves (inlet turbine valves) have been refurbished on the first two Pelton turbine units. The valve closure is controlled by the valve actuator (hydraulic servomotor). Because the torque acting on the valve body is dependent on flow conditions the valve closing time may vary significantly for different flow velocities (passive valve). For the passive valve the torques acting on the valve body should be considered in the valve model. The valve closing time results from numerical simulation. On the contrary, for the active valve the valve closing time is assumed prior to simulation. The spherical valve boundary condition is incorporated into the method of characteristics (MOC) algorithm. The staggered (diamond) grid in applying the MOC is used in this paper. The passive valve boundary condition is described by the water hammer equations, the valve equation that relates discharge to pressure head drop and the dynamic equation of the valve body motion (torque equation). The active valve boundary condition is described by the first two equations, respectively. Standard quasi-steady friction model is used for estimating friction losses in plant's tunnel and penstocks. Numerical results using both the active and the passive spherical valve models are compared with results of measurements. It has been found that the influence of flow conditions on the spherical valve closing time is minor for the cases considered. Computed and measured results agree reasonably well.

  13. Water hammer caused by closure of turbine safety spherical valves

    Energy Technology Data Exchange (ETDEWEB)

    Karadzic, U; Vukoslavcevic, P [Faculty of Mechanical Engineering, University of Montenegro Dzordza Vasingtona nn, Podgorica, 81000 (Montenegro); Bergant, A, E-mail: uros.karadzic@ac.m [LitostrojPower d.o.o., Litostrojska 50, Ljubljana, 1000 (Slovenia)

    2010-08-15

    This paper investigates water hammer effects caused by closure of spherical valves against the discharge. During the first phase of modernisation of Perucica high-head hydropower plant (HPP), Montenegro, safety spherical valves (inlet turbine valves) have been refurbished on the first two Pelton turbine units. The valve closure is controlled by the valve actuator (hydraulic servomotor). Because the torque acting on the valve body is dependent on flow conditions the valve closing time may vary significantly for different flow velocities (passive valve). For the passive valve the torques acting on the valve body should be considered in the valve model. The valve closing time results from numerical simulation. On the contrary, for the active valve the valve closing time is assumed prior to simulation. The spherical valve boundary condition is incorporated into the method of characteristics (MOC) algorithm. The staggered (diamond) grid in applying the MOC is used in this paper. The passive valve boundary condition is described by the water hammer equations, the valve equation that relates discharge to pressure head drop and the dynamic equation of the valve body motion (torque equation). The active valve boundary condition is described by the first two equations, respectively. Standard quasi-steady friction model is used for estimating friction losses in plant's tunnel and penstocks. Numerical results using both the active and the passive spherical valve models are compared with results of measurements. It has been found that the influence of flow conditions on the spherical valve closing time is minor for the cases considered. Computed and measured results agree reasonably well.

  14. Development and application of underwater robot vehicle for close inspection of spent fuels

    Energy Technology Data Exchange (ETDEWEB)

    Yun, J. S.; Park, B. S.; Song, T. G.; Kim, S. H.; Cho, M. W.; Ahn, S. H.; Lee, J. Y.; Oh, S. C.; Oh, W. J.; Shin, K. W.; Woo, D. H.; Kim, H. G.; Park, J. S

    1999-12-01

    The research and development efforts of the underwater robotic vehicle for inspection of spent fuels are focused on the development of an robotic vehicle which inspects spent fuels in the storage pool through remotely controlled actuation. For this purpose, a self balanced vehicle actuated by propellers is designed and fabricated, which consists of a radiation resistance camera, two illuminators, a pressure transducer and a manipulator. the algorithm for autonomous navigation is developed and its performance is tested at the swimming pool. The results of the underwater vehicle shows that the vehicle can easily navigate into the arbitrary directions while maintaining its balanced position. The camera provides a clear view of working environment by using the macro and zoom functions. The camera tilt device provides a wide field of view which is enough for monitoring the operation of manipulator. Also, the manipulator can pick up the dropped objects up to 4 kgf of weight. (author)

  15. Cladding tube materials for advanced nuclear facilities with closed fuel cycle

    Energy Technology Data Exchange (ETDEWEB)

    Bartosova, I. [Slovenska technicka univerzita v Bratislave, Fakulta elektrotechniky a informatiky, Ustav jadroveho a fyzikalneho inzinierstva, 81219 Bratislava (Slovakia)

    2013-04-16

    The paper is aimed on perspective materials for fuel cladding in advanced nuclear reactors. Samples of Eurofer and ODS Eurofer were studied by various techniques such as Positron Annihilation Lifetime Spectroscopy, Vickers Hardness and Coincidence Doppler Broadening. After studying the samples by these methods, we implanted them by Helium atoms to simulate irradiation damage. Samples were then remeasured by Positron Annihilation Lifetime Spectroscopy to determine the affect of implantation on its behavior. (authors)

  16. Perspective on the French closed fuel cycle: Open towards energy future and sustainability

    International Nuclear Information System (INIS)

    Tinturier, Bernard; Debes, Michel; Delbecq, Jean-Michel

    2006-01-01

    Energy sustainability and nuclear energy nowadays are far reaching issues with many implications and as a consequence, any long term sustainable strategy needs to be flexible. In France, nuclear energy (427 TWh in 2004, 80% of national electricity production) is a major asset for clean electricity production and for meeting Kyoto protocol objective in France. The decision to build a future EPR reactor in France has been taken. Regarding back end and fuel cycle, the current reprocessing and recycling strategy, with the existing industrial system (Cogema La Hague and Melox), has proven to be reliable and efficient. It enables to meet sustainability requirements, now and in the long run: ensuring a good management of high level waste through vitrification, reducing the amount of nuclear spent fuel in interim storage, recycling valuable nuclear material (Pu), keeping the possibility to use Pu concentrated in MOX spent fuel to start FBR in the future. To maintain this possibility for the far future, EDF considers that the Generation IV program is of major importance in order to develop future fast reactors able to use plutonium and to ensure a full utilization of uranium resource, while optimizing high level waste management. EDF strategy is to keep the nuclear option open in the future, with a two-steps approach for the renewal of the current nuclear fleet: first, around 2020, with the launching of generation III reactors like EPR, and second, depending on the energy demand, launching of Generation IV systems, around 2040 or beyond. To meet this energy prospect, R and D efforts must be devoted to fast breeder reactors (sodium cooled, which benefits already from industrial experience, and gas cooled, under consideration for R and D). Globally, this strategy is open to future progress and optimisation as needed to meet long term energy sustainability. It appears the necessity of a good consistency between all the components of the nuclear system: reactors, fuel cycle

  17. Butterfly valve of all rubber lining type

    International Nuclear Information System (INIS)

    Shimada, Shosaku; Nakatsuma, Sumiya; Sasaki, Iwao; Aoki, Naoshi.

    1982-01-01

    The valves used for the circulating water pipes for condensers in nuclear and thermal power stations have become large with the increase of power output, and their specifications have become strict. The materials for the valves change from cast iron to steel plate construction. To cope with sea water corrosion, rubber lining has been applied to the internal surfaces of valve boxes, and the build-up welding of stainless steel has been made on the edges of valves. However, recently it is desired to develop butterfly valves, of which the whole valve disks are lined with hard rubber. For the purpose of confirming the performance of large bore valves, a 2600 mm bore butterfly valve of all rubber lining type was used, and the opening and closing test of 1100 times was carried out by applying thermal cycle and pressure difference and using artifical sea water. Also the bending test of hard rubber lining was performed with test pieces. Thus, it was confirmed that the butterfly valves of all rubber lining type have the performance exceeding that of the valves with build-up welding. The course of development of the valves of all rubber lining type, the construction and the items of confirmation by tests of these valves, and the tests of the valve and the hard rubber lining described above are reported. (Kako, I.)

  18. Remotely handled and remotely operated valve, particularly for the hot part of radioactive plants

    International Nuclear Information System (INIS)

    Radovan, G.; Sandling, M.J.; Davidson, J.W.; Blaseck, K.; Hoffmeister, L.; Westendorf, H.

    1988-01-01

    The valve consists of a valve whose valve housing is built into a pipeline. The wear parts of the valve to be replaced, such as the valve body and valve seat, are combined into a replacement part. The replacement part and a clamp act together so that the replacement part is interlocked with the valve housing in the closed operating position. The exchange can be made by undoing a single central screw. (DG) [de

  19. 40 CFR 63.1034 - Closed vent systems and control devices; or emissions routed to a fuel gas system or process...

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 10 2010-07-01 2010-07-01 false Closed vent systems and control devices; or emissions routed to a fuel gas system or process standards. 63.1034 Section 63.1034 Protection... routed to a fuel gas system or process standards. (a) Compliance schedule. The owner or operator shall...

  20. The transport of irradiated fuel. An activity closely related to reprocessing

    International Nuclear Information System (INIS)

    Lenail, B.; Curtis, H.W.

    1987-01-01

    With a proven reprocessing capacity of 400 tonnes of uranium per year and the rapid expansion of this capacity, the need to feed the reprocessing plants at La Hague has become vital to ensure continuous and economic reprocessing. The programming of transports by the reprocessor and transporter to ensure a constant supply of fuel for reprocessing has therefore become increasingly important. These transports use the public roads and the railway system and the reprocessor and transporter must cooperate in maintaining the highest possible standards of safety. Safety must take priority over all other factors, including the economics of the operation

  1. Extracellular Matrix Biomarker, Fibulin-1, Is Closely Related to NT-proBNP and Soluble Urokinase Plasminogen Activator Receptor in Patients with Aortic Valve Stenosis (The SEAS Study)

    DEFF Research Database (Denmark)

    Kruger, Ruan; Rasmussen, Lars M; Argraves, William S

    2014-01-01

    associated with subclinical atherosclerosis. Therefore, we aimed to explore the interplay between these biomarkers and mild to moderate aortic valve stenosis (AS). METHODS: In 374 patients with mild to moderate AS, we investigated the relationship of fibulin-1 with NT-proBNP, levels of suPAR and the degree.......01), and suPAR (βyear0 = 0.09, p = 0.26, βyear1 = 0.23, βyear4 = 0.21, both plevels of fibulin-1 were independently associated with higher levels of suPAR and NT-proBNP especially in patients with lower AVAI, suggesting...

  2. Synthesis and analysis of a closed cycle methane-fueled marine energy process

    International Nuclear Information System (INIS)

    Teich, C.I.

    1983-01-01

    A marine energy system has been synthesized from state-of-the-art technology to convert nuclear derived electricity into liquefied methane. In the first part of the process, the on-board process, liquid methane is burned in a combined gas turbine-steam turbine system to provide propulsion power and the carbon dioxide created during combustion recovered. In the second part of the process, the fuel regeneration process, the methane is regenerated in a centralized land-based facility by the reaction of the recovered carbon dioxide with hydrogen obtained from nuclear-powered electrolysis of water. The system was analyzed by combining thermodynamic available energy analysis and an approximate preliminary design. The available energy analysis of the combined system established the thermodynamic feasibility of the methane-carbon dioxide cycle and resulted in various process improvements because of the inefficiencies disclosed by the analysis. The more critical on-board process was analyzed and developed further by a capital cost optimization and ranking alternate process options by their available energy consumptions. The optimal on-board process, whose capital cost is 16% less than the preliminary design, has an effectiveness of 47% and the fuel regeneration process an effectiveness of 56%. It was also found that the process cost was proportional to the horsepower raised to the seven-tenths power

  3. Leakage characterization of a piloted power operated relief valve

    International Nuclear Information System (INIS)

    Ezekoye, L.I.; Hess, M.D.

    1995-01-01

    In Westinghouse Pressurized Water Reactors (PWRs), power operated relief valves (PORVs) are used to provide overpressure protection of the Pressurizer. The valves are fail closed globe valves which means that power is required to open the valves and, on loss of power, the valves close. There are two ways to operate the PORVs. The more common way is to directly couple the disc to an actuator via a disc-stem assembly. The type of design is not the object of this paper. The other and less common way of operating a PORV is by piloting the main valve such that the opening or closing of a pilot valve opens and closes the main valve. This is the design of interest. In most plants, the PORVs are installed with a water loop seal while in some plants no water loop seals are used. It is generally accepted that loop seal installation minimizes valve seat leakage. In non-loop seal installation, the valve seat is exposed to steam which increases the potential for seat leakage. This paper describes the results of some tests performed with nitrogen and steam to characterize the leakage potential of a pilot operated PORV. The test results were compared with seat leakage tests of check valves to provide insight on the leakage testing of pilot operated valves and check valves. The paper also compares the test data with leakage estimates using the ASME/ANSI OM Code guidance on valve leakage

  4. Piezoelectric valve

    Science.gov (United States)

    Petrenko, Serhiy Fedorovich

    2013-01-15

    A motorized valve has a housing having an inlet and an outlet to be connected to a pipeline, a saddle connected with the housing, a turn plug having a rod, the turn plug cooperating with the saddle, and a drive for turning the valve body and formed as a piezoelectric drive, the piezoelectric drive including a piezoelectric generator of radially directed standing acoustic waves, which is connected with the housing and is connectable with a pulse current source, and a rotor operatively connected with the piezoelectric generator and kinematically connected with the rod of the turn plug so as to turn the turn plug when the rotor is actuated by the piezoelectric generator.

  5. Transport device for nuclear fuel powder

    International Nuclear Information System (INIS)

    Adelmann, M.

    1987-01-01

    The transport device for nuclear fuel powder, which does not disintegrate during transport, has a transport pipe which starts with its entry end from the floor or a closed container and opens with its outlet end at the top into a closed separation container connect via a powder filter to a suction pump. By alternate regular opening and closing of a first control valve for transport gas fitted to a transport pipe to a supply duct and a second control valve for transport gas fitted to the container to an additional supply duct, alternating plugs of nuclear fuel powder and transport gas cushions are formed and are transported to the outlet end of the transport pipe. (orig./HP) [de

  6. A closed-loop biorefining system to convert organic residues into fuels

    Science.gov (United States)

    Chen, Rui

    This project delivers an energy positive and water neutral, closed-loop biorefining system that converts organic wastes into renewable energy and reduces the overall impacts on the environment. The research consisted of three major stages: The first stage of this project was conducted in an anaerobic co-digestion system. Effects of the ratio of dairy manure-to-food waste as well as operating temperature were tested on the performance of the co-digestion system. Results illustrated an increase in biogas productivity with the increase of supplemental food waste; fiber analysis revealed similar chemical composition (cellulose, hemicellulose and lignin) of final solid digestate regardless their different initial feedstock blends and digestion conditions. The molecular genetic analyses demonstrated that anaerobic methanogenic microorganisms were able to adjust their community assemblage to maximize biogas production and produce homogenized solid digestate. The second stage utilized electrocoagulation (EC) pretreated liquid digestate from previous stage to culture freshwater algae. Kinetics study showed a similar maximum growth rate (0.201-0.207 g TS day-1) in both 2x and 5x dilutions of EC solution; however, the algal growth was inhibited in original EC solution (1x), possibly due to the high ammonia-to-phosphate ratio. Algal community assemblage changed drastically in different dilutions of EC solution after a 9-day culture. The following semi-continuous culture in 2x and 5x EC media established steady biomass productivities and nitrogen removal rates; in addition, both conditions illustrated a phenomenon of phosphorus luxury uptake. Biomass composition analyses showed that algae cultured in medium containing higher nitrogen (2x EC medium) accumulated more protein but less carbohydrate and lipid than the 5x EC medium. The last stage involved hydrolyzing the algal biomass cultured in anaerobic digestion effluent and analyzing the effects of the neutralized algal

  7. Variable valve timing in a homogenous charge compression ignition engine

    Science.gov (United States)

    Lawrence, Keith E.; Faletti, James J.; Funke, Steven J.; Maloney, Ronald P.

    2004-08-03

    The present invention relates generally to the field of homogenous charge compression ignition engines, in which fuel is injected when the cylinder piston is relatively close to the bottom dead center position for its compression stroke. The fuel mixes with air in the cylinder during the compression stroke to create a relatively lean homogeneous mixture that preferably ignites when the piston is relatively close to the top dead center position. However, if the ignition event occurs either earlier or later than desired, lowered performance, engine misfire, or even engine damage, can result. The present invention utilizes internal exhaust gas recirculation and/or compression ratio control to control the timing of ignition events and combustion duration in homogeneous charge compression ignition engines. Thus, at least one electro-hydraulic assist actuator is provided that is capable of mechanically engaging at least one cam actuated intake and/or exhaust valve.

  8. Experimental validation of the fluid–structure interaction simulation of a bioprosthetic aortic heart valve

    International Nuclear Information System (INIS)

    Kemp, I.; Dellimore, K.; Rodriguez, R.; Scheffer, C.; Blaine, D.; Weich, H.; Doubell, A.

    2013-01-01

    Experiments performed on a 19 mm diameter bioprosthetic valve were used to successfully validate the fluid–structure interaction (FSI) simulation of an aortic valve at 72 bpm. The FSI simulation was initialized via a novel approach utilizing a Doppler sonogram of the experimentally tested valve. Using this approach very close quantitative agreement (≤12.5 %) between the numerical predictions and experimental values for several key valve performance parameters, including the peak systolic transvalvular pressure gradient, rapid valve opening time and rapid valve closing time, was obtained. The predicted valve leaflet kinematics during opening and closing were also in good agreement with the experimental measurements.

  9. Butterfly valve torque prediction methodology

    International Nuclear Information System (INIS)

    Eldiwany, B.H.; Sharma, V.; Kalsi, M.S.; Wolfe, K.

    1994-01-01

    As part of the Motor-Operated Valve (MOV) Performance Prediction Program, the Electric Power Research Institute has sponsored the development of methodologies for predicting thrust and torque requirements of gate, globe, and butterfly MOVs. This paper presents the methodology that will be used by utilities to calculate the dynamic torque requirements for butterfly valves. The total dynamic torque at any disc position is the sum of the hydrodynamic torque, bearing torque (which is induced by the hydrodynamic force), as well as other small torque components (such as packing torque). The hydrodynamic torque on the valve disc, caused by the fluid flow through the valve, depends on the disc angle, flow velocity, upstream flow disturbances, disc shape, and the disc aspect ratio. The butterfly valve model provides sets of nondimensional flow and torque coefficients that can be used to predict flow rate and hydrodynamic torque throughout the disc stroke and to calculate the required actuation torque and the maximum transmitted torque throughout the opening and closing stroke. The scope of the model includes symmetric and nonsymmetric discs of different shapes and aspects ratios in compressible and incompressible fluid applications under both choked and nonchoked flow conditions. The model features were validated against test data from a comprehensive flowloop and in situ test program. These tests were designed to systematically address the effect of the following parameters on the required torque: valve size, disc shapes and disc aspect ratios, upstream elbow orientation and its proximity, and flow conditions. The applicability of the nondimensional coefficients to valves of different sizes was validated by performing tests on 42-in. valve and a precisely scaled 6-in. model. The butterfly valve model torque predictions were found to bound test data from the flow-loop and in situ testing, as shown in the examples provided in this paper

  10. Controllable valve in a nuclear reactor system

    International Nuclear Information System (INIS)

    Schabert, H.P.; Laurer, E.

    1980-01-01

    The quick-acting gate valve of the PWR is opened and closed by means of two pistons and live steam. One of the pistons is connected to the valve disk by a piston rod which is concentrically lead into another hollow piston rod being connected to the second piston. Stops limit the strokes of the two pistons. (GL) [de

  11. A Science-Based Approach to Understanding Waste Form Durability in Open and Closed Nuclear Fuel Cycles

    International Nuclear Information System (INIS)

    M.T. Peters; R.C. Ewing

    2006-01-01

    There are two compelling reasons for understanding source term and near-field processes in a radioactive waste geologic repository. First, almost all of the radioactivity is initially in the waste form, mainly in the spent nuclear fuel (SNF) or nuclear waste glass. Second, over long periods, after the engineered barriers are degraded, the waste form is a primary control on the release of radioactivity. Thus, it is essential to know the physical and chemical state of the waste form after hundreds of thousands of years. The United States Department of Energy's Yucca Mountain Repository Program has initiated a long-term program to develop a basic understanding of the fundamental mechanisms of radionuclide release and a quantification of the release as repository conditions evolve over time. Specifically, the research program addresses four critical areas: (a) SNF dissolution mechanisms and rates; (b) formation and properties of U 6+ -secondary phases; (c) waste form-waste package interactions in the near-field; and (d) integration of in-package chemical and physical processes. The ultimate goal is to integrate the scientific results into a larger scale model of source term and near-field processes. This integrated model will be used to provide a basis for understanding the behavior of the source term over long time periods (greater than 10 5 years). Such a fundamental and integrated experimental and modeling approach to source term processes can also be readily applied to development of advanced waste forms as part of a closed nuclear fuel cycle. Specifically, a fundamental understanding of candidate waste form materials stability in high temperature/high radiation environments and near-field geochemical/hydrologic processes could enable development of advanced waste forms ''tailored'' to specific geologic settings

  12. A Science-Based Approach to Understanding Waste Form Durability in Open and Closed Nuclear Fuel Cycles

    International Nuclear Information System (INIS)

    Peters, M.T.; Ewing, R.C.

    2007-01-01

    There are two compelling reasons for understanding source term and near-field processes in a radioactive waste geologic repository. First, almost all of the radioactivity is initially in the waste form, mainly in the spent nuclear fuel (SNF) or nuclear waste glass. Second, over long periods, after the engineered barriers are degraded, the waste form is a primary control on the release of radioactivity. Thus, it is essential to know the physical and chemical state of the waste form after hundreds of thousands of years. The United States Department of Energy's Yucca Mountain Repository Program has initiated a long-term program to develop a basic understanding of the fundamental mechanisms of radionuclide release and a quantification of the release as repository conditions evolve over time. Specifically, the research program addresses four critical areas: a) SNF dissolution mechanisms and rates; b) formation and properties of U 6+ - secondary phases; c) waste form-waste package interactions in the near-field; and d) integration of in-package chemical and physical processes. The ultimate goal is to integrate the scientific results into a larger scale model of source term and near-field processes. This integrated model will be used to provide a basis for understanding the behavior of the source term over long time periods (greater than 10 5 years). Such a fundamental and integrated experimental and modeling approach to source term processes can also be readily applied to development of advanced waste forms as part of a closed nuclear fuel cycle. Specifically, a fundamental understanding of candidate waste form materials stability in high temperature/high radiation environments and near-field geochemical/hydrologic processes could enable development of advanced waste forms 'tailored' to specific geologic settings. (authors)

  13. Studies of valve lifter for automotive heavy duty diesel engine by ceramic materials. I. Development of ceramic-metal joint by brazing method

    Energy Technology Data Exchange (ETDEWEB)

    Yun, H W [Technical Centre of KIA-ASIA MOTORS (Korea, Republic of); Han, I S [Korea Institute of Energy Research, Tajeon (Korea, Republic of); Lim, Y S; Chung, Y J [Myong Ji University (Korea, Republic of)

    1998-02-01

    Continuously contacting with camshaft, the face of Valve Lifter, made of cast iron, brings about abnormal wear such as unfair wear or early wear because it is heavily loaded in the valve train system as the engine gets more powered. This abnormal sear becomes a defect namely over-clearance when the valve is lifting so that the fuel gas imperfectly combusted by unsuitable open or close action of engine valve in the combustion chamber. The imperfect combustion, in the end, results in the major causes of air pollution and decrease of the engine output. Consequently, to prevent this wear, this study was to develop the valve lifter which is joined by brazing process with SCM435H and a tip by manufacturing the face as a superhardened ceramics alloy which has high wear resistance. Having the excellent surface hardness with Hv1100-1200, the sintered body developed with superhardened alloy(WC) can endure the severe face loading in the valve train system. We experienced with various brazing alloys and obtained the excellent joining strength to the joint had 150 MPa shear strength. Interface analysis and microstructure in a joint were examined through SEM and EDS, Optical microscope. Also, 2,500 hours, high speed(3,000{approx}4,000 rpm) and continuous (1step 12hr) engine dynamo testing was carried out to the casting valve lifter and ceramics-metal joint valve lifter so that the abnormal wears were compared and evaluated.

  14. Aortic valve bypass

    DEFF Research Database (Denmark)

    Lund, Jens T; Jensen, Maiken Brit; Arendrup, Henrik

    2013-01-01

    In aortic valve bypass (AVB) a valve-containing conduit is connecting the apex of the left ventricle to the descending aorta. Candidates are patients with symptomatic aortic valve stenosis rejected for conventional aortic valve replacement (AVR) or transcatheter aortic valve implantation (TAVI). ...

  15. A correlation for safety valve blowdown and ring settings

    International Nuclear Information System (INIS)

    Singh, A.; Shak, D.

    1982-01-01

    The blowdown of a spring loaded safety valve is defined as the difference between the pressure at which the valve opens and the pressure at which the valve fully closes under certain fluid flow conditions. Generally, the blowdown is expressed in terms of percentage of the opening pressure. An extensive series of tests carried out in the EPRI/PWR Utilities Valve Test Program has shown that the blowdown of safety valves can in general be strongly dependent upon the valve geometry and other parameters such as ring adjustments, spring stiffness, backpressure etc. In the present study, correlations have been developed using the EPRI safety valve test data to predict the expected blowdown as a function of adjustment ring settings for geometrically similar valves under steam discharge conditions. The correlation is validated against two different size Dresser valves

  16. Thermally induced pressure locking of gate valves: A survey of valve bonnet pressurization rates

    International Nuclear Information System (INIS)

    Ezekoye, L.I.; Moore, W.E.

    1996-01-01

    Closed, water filled gate valves run the risk of becoming pressurized due to heat input from the environment or from adjacent connected piping. Thermal pressurization of gate valve bonnets may lead to the valves failing to open on demand and can even induce structural failure of valves. This paper presents an analytical prediction of the pressurization rate of a closed pressure vessel subject to uniform heating which may be considered as an upper bound to the pressurization rate that may occur in the field. Then actual valve experiences described in the literature are reviewed to determine the expected pressurization rate in existing hardware designs. A statistical approach is applied to reconcile the differing pressurization rates reported in the literature and determine a rate that can be applied in valve evaluations. The limitations of the reconciled rate are discussed

  17. Computerized information system for inventory-taking and verification at a nuclear fuel fabrication plant with closed production lines

    International Nuclear Information System (INIS)

    Bahm, W.; Brueckner, C.; Hartmann, G.

    1976-01-01

    By means of a model the use of electronic data processing is studied for preparing inventory listings and for inventory verification in a fabrication plant for Pu-U mixed-oxide fuel pins. It is postulated that interruptions in operation should be avoided as much as possible. Closed-Line production is assumed so that access to nuclear material calls for special withdrawal via locks. The production line is subdivided into sections with measuring points placed in between to record the nuclear material flow. The measured results are fed to a central data acquisition and reporting system capable of calculating on-line from these results the book inventories present in the individual sections. Inventory-taking and verification are carried out simultaneously in the sections of the production line using the EDP system. The production is not interrupted for this purpose. The production stream is tagged prior to reaching a section to be measured and is subsequently measured when entering the respective section until the tag has reached the end of the section. The measurement can be verified by inspectors. Movements of nuclear materials in and from other plant areas such as the storage area are likewise fed into the central data processing system so that inventory lists can be recalled at any moment. By this means the inventory can be taken quickly and at any time. The inventory is verified in the conventional way. (author)

  18. Engine including hydraulically actuated valvetrain and method of valve overlap control

    Science.gov (United States)

    Cowgill, Joel [White Lake, MI

    2012-05-08

    An exhaust valve control method may include displacing an exhaust valve in communication with the combustion chamber of an engine to an open position using a hydraulic exhaust valve actuation system and returning the exhaust valve to a closed position using the hydraulic exhaust valve actuation assembly. During closing, the exhaust valve may be displaced for a first duration from the open position to an intermediate closing position at a first velocity by operating the hydraulic exhaust valve actuation assembly in a first mode. The exhaust valve may be displaced for a second duration greater than the first duration from the intermediate closing position to a fully closed position at a second velocity at least eighty percent less than the first velocity by operating the hydraulic exhaust valve actuation assembly in a second mode.

  19. Worchester Solenoid Actuated Gas Operated MCO Isolation Valves

    International Nuclear Information System (INIS)

    VAN KATWIJK, C.

    2000-01-01

    These valves are 1 inch gas-operated full-port ball valves incorporating a solenoid and limit switches as integral parts of the actuator that are used in process streams within the CVDF hood. The valves fail closed (on loss of pressure or electrical) to prevent MCO vent drain to either reduce air in-leakage or loss of He. The valves have couplings for transverse actuator mounting

  20. Worcester Solenoid-Actuated Gas Operated MCO Isolation Valves

    International Nuclear Information System (INIS)

    VAN KATWIJK, C.

    2000-01-01

    These valves are 1 inch gas-operated full-port ball valves incorporating a solenoid and limit switches as Integral parts of the actuator that are used in different process streams within the CVDF hood. The valves fail closed (on loss of pressure or electrical) for MCO isolation to either reduce air in leakage or loss of He. All valves have coupling for transverse actuator mounting

  1. Transcatheter aortic valve replacement

    Science.gov (United States)

    ... gov/ency/article/007684.htm Transcatheter aortic valve replacement To use the sharing features on this page, please enable JavaScript. Transcatheter aortic valve replacement (TAVR) is surgery to replace the aortic valve. ...

  2. Magnetically operated check valve

    Science.gov (United States)

    Morris, Brian G.; Bozeman, Richard J., Jr.

    1994-06-01

    A magnetically operated check valve is disclosed. The valve is comprised of a valve body and a movable poppet disposed therein. A magnet attracts the poppet to hold the valve shut until the force of fluid flow through the valve overcomes the magnetic attraction and moves the poppet to an unseated, open position. The poppet and magnet are configured and disposed to trap a magnetically attracted particulate and prevent it from flowing to a valve seating region.

  3. Study of a Fuel Supply Pump with a Piezoelectric Effect for Microdirect Alcohol Fuel Cells

    OpenAIRE

    Ma, Hsiao-Kang; Wang, Jyun-Sheng; Cheng, Wei-Yang; Huang, Shin-Han

    2011-01-01

    A novel design for an ethanol injection system has been proposed, which consists of one pump chamber, two valves, and one central-vibrating piezoelectric device. The system uses a microdiaphragm pump with a piezoelectric device for microdirect alcohol fuel cells. The diameters of the pump chamber are 31 mm and 23 mm, and the depths of the chamber are 1 mm and 2 mm. When the piezoelectric device actuates for changing pump chamber volume, the valves will be opened/closed, and the ethanol will b...

  4. What Is Heart Valve Surgery?

    Science.gov (United States)

    ... working correctly. Most valve replacements involve the aortic Tricuspid valve and mitral valves. The aortic valve separates ... where it shouldn’t. This is called incompetence, insufficiency or regurgitation. • Prolapse — mitral valve flaps don’t ...

  5. What Is Heart Valve Disease?

    Science.gov (United States)

    ... and replacing it with a man-made or biological valve. Biological valves are made from pig, cow, or human ... the valve. Man-made valves last longer than biological valves and usually don’t have to be ...

  6. Fast-acting valve actuator

    Science.gov (United States)

    Cho, Nakwon

    1980-01-01

    A fast-acting valve actuator utilizes a spring driven pneumatically loaded piston to drive a valve gate. Rapid exhaust of pressurized gas from the pneumatically loaded side of the piston facilitates an extremely rapid piston stroke. A flexible selector diaphragm opens and closes an exhaust port in response to pressure differentials created by energizing and de-energizing a solenoid which controls the pneumatic input to the actuator as well as selectively providing a venting action to one side of the selector diaphragm.

  7. Griswold Tempered Water Flow Regulator Valves Used as Anti-Siphon Valves

    International Nuclear Information System (INIS)

    MISKA, C.

    2000-01-01

    FCV-1*22 and 1*23 are Griswold constant flow regulators used as anti-siphon valves in the tempered water system, they fail closed but valve cartridge orifice allows minimum flow to prevent loss of water from the MCO/CASK annulus

  8. Investigation of the effect of different carbon film thickness on the exhaust valve

    Science.gov (United States)

    Karamangil, M. I.; Avci, A.; Bilal, H.

    2008-03-01

    Valves working under different loads and temperatures are the mostly forced engine elements. In an internal combustion engine, pressures and temperatures affecting on the valves vary with fuel type and the combustion characteristics of the fuel. Consequently, valves are exposed to different dynamic and thermal stress. In this study, stress distributions and temperature profiles on exhaust valve are obtained depending on different carbon film thickness. It is concluded that heat losses and valve temperatures decrease and valve surfaces are exposed to less thermal shocks with increasing carbon film thickness.

  9. A study of fluid flow and combustion with variable valve timing

    Energy Technology Data Exchange (ETDEWEB)

    Soederberg, F

    1998-10-01

    The effects of variable valve timing (VVT) were examined by in-cylinder Laser Doppler Velocimetry flow measurements and heat-release calculations. A single-cylinder Volvo B5254 engine was used for all experiments and the valve timing was altered by phasing or exchanging the camshaft. Special cam lobes were developed for simulation of throttle-less operation. With the standard double camshaft, a tumbling flow was generated and with valve deactivation, a swirling flow was generated. The turbulence was increased with valve deactivation. This increased the combustion rate making lean burn possible. The standard camshaft with inlet valve deactivation and late cam phasing had a faster combustion at {lambda} = 1.8 than the standard camshaft with normal cam phasing at {lambda} = 1.0. Early and late inlet valve closing was used for enabling throttle-less operation. Early inlet valve closing (EIVC) generated a very slow tumble with low turbulence. Late inlet valve closing generated both very high and low turbulence. The net indicated efficiency was improved with up to 10%. Some reduction was observed for the gross indicated efficiency, due to a too large reduction in effective compression ratio. A very stable combustion was obtained for EIVC with gasoline, possibly due to a sheering flow over the inlet valves resulting in improved fuel-air preparation. Wavelet analysis was used for dividing LDV flow measurements into time and frequency resolved information. The technique rendered the same flow results as the moving window technique, but with a separation of the turbulence into different frequencies. The choice of wavelet was shown not to be crucial. The frequency resolved turbulence was studied for tumble and swirl. A tumbling flow had a larger transfer of energy from low frequency turbulence into high frequency turbulence than a swirling flow. This is caused by the tumble breakdown. A correlation against heat-release indicated that high frequency turbulence have a larger

  10. Effects of valve timing, valve lift and exhaust backpressure on performance and gas exchanging of a two-stroke GDI engine with overhead valves

    International Nuclear Information System (INIS)

    Dalla Nora, Macklini; Lanzanova, Thompson Diórdinis Metzka; Zhao, Hua

    2016-01-01

    Highlights: • Two-stroke operation was achieved in a four-valve direct injection gasoline engine. • Shorter valve opening durations improved torque at lower engine speeds. • The longer the valve opening duration, the lower was the air trapping efficiency. • Higher exhaust backpressure and lower valve lift reduced the compressor work. - Abstract: The current demand for fuel efficient and lightweight powertrains, particularly for application in downsized and hybrid electric vehicles, has renewed the interest in two-stroke engines. In this framework, an overhead four-valve spark-ignition gasoline engine was modified to run in the two-stroke cycle. The scavenging process took place during a long valve overlap period around bottom dead centre at each crankshaft revolution. Boosted intake air was externally supplied at a constant pressure and gasoline was directly injected into the cylinder after valve closure. Intake and exhaust valve timings and lifts were independently varied through an electrohydraulic valve train, so their effects on engine performance and gas exchanging were investigated at 800 rpm and 2000 rpm. Different exhaust backpressures were also evaluated by means of exhaust throttling. Air trapping efficiency, charging efficiency and scavenge ratio were calculated based on air and fuel flow rates, and exhaust oxygen concentration at fuel rich conditions. The results indicated that longer intake and exhaust valve opening durations increased the charge purity and hence torque at higher engine speeds. At lower speeds, although, shorter valve opening durations increased air trapping efficiency and reduced the estimated supercharger power consumption due to lower air short-circuiting. A strong correlation was found between torque and charging efficiency, while air trapping efficiency was more associated to exhaust valve opening duration. The application of exhaust backpressure, as well as lower intake/exhaust valve lifts, made it possible to increase

  11. Radiological visualization of prosthetic heart valves in situ

    International Nuclear Information System (INIS)

    Hoffmeister, H.M.; Pirschel, J.

    1986-01-01

    To determine the radiographic appearance of prosthetic heart valves 15 different models were investigated in situ. Fluoroscopy with detail radiographs and standard chest-radiographs were used for identification of the specific type of the prosthesis, for determination of details of the valve apparatus and for evaluation of the motion of the valve disc/ball. - Fluoroscopy and routine radiographs provided sufficient information to identify all prosthetic heart valves with exception of the Xenomedica bioprosthesis. If radiopaque material was used for the valve disc/ball, fluoroscopic assessment of the function of the valve was possible. Thus, in most types of disc or ball valves the opening/closing of the valve can be visualized, whereas in bioprosthesis a radiological determination of the mechanical function is not possible. (orig.) [de

  12. Non intrusive check valve diagnostics at Bruce A

    International Nuclear Information System (INIS)

    Marsch, S.P.

    1997-01-01

    Bruce A purchased non intrusive check valve diagnostic equipment in 1995 to ensure operability and availability of critical check valves in the Station. Diagnostics can be used to locate and monitor check valve degradation modes. Bruce A initiated a pilot program targeting check valves with flow through them and ones that completed open or close cycles. Approaches to determine how to confirm operability of passive check valves using non intrusive techniques were explored. A sample population of seventy-three check valves was selected to run the pilot program on prior to complete implementation. The pilot program produced some significant results and some inconclusive results. The program revealed a major finding that check valve performance modeling is required to ensure continuous operability of check valves. (author)

  13. Non intrusive check valve diagnostics at Bruce A

    Energy Technology Data Exchange (ETDEWEB)

    Marsch, S.P. [Ontario Hydro, Bruce Nuclear Generating Station A, Tiverton, ON (Canada)

    1997-07-01

    Bruce A purchased non intrusive check valve diagnostic equipment in 1995 to ensure operability and availability of critical check valves in the Station. Diagnostics can be used to locate and monitor check valve degradation modes. Bruce A initiated a pilot program targeting check valves with flow through them and ones that completed open or close cycles. Approaches to determine how to confirm operability of passive check valves using non intrusive techniques were explored. A sample population of seventy-three check valves was selected to run the pilot program on prior to complete implementation. The pilot program produced some significant results and some inconclusive results. The program revealed a major finding that check valve performance modeling is required to ensure continuous operability of check valves. (author)

  14. Microfluidic sieve valves

    Science.gov (United States)

    Quake, Stephen R; Marcus, Joshua S; Hansen, Carl L

    2015-01-13

    Sieve valves for use in microfluidic device are provided. The valves are useful for impeding the flow of particles, such as chromatography beads or cells, in a microfluidic channel while allowing liquid solution to pass through the valve. The valves find particular use in making microfluidic chromatography modules.

  15. Rotary pneumatic valve

    Science.gov (United States)

    Hardee, Harry C.

    1991-01-01

    A rotary pneumatic valve which is thrust balanced and the pneumatic pressure developed produces only radial loads on the valve cylinder producing negligible resistance and thus minimal torque on the bearings of the valve. The valve is multiplexed such that at least two complete switching cycles occur for each revolution of the cylinder spindle.

  16. Aortic Valve Stenosis

    Science.gov (United States)

    ... most cases, doctors don't know why a heart valve fails to develop properly, so it isn't something you could have prevented. Calcium buildup on the valve. With age, heart valves may accumulate deposits of calcium (aortic valve ...

  17. Remote actuated valve implant

    Science.gov (United States)

    McKnight, Timothy E; Johnson, Anthony; Moise, Jr., Kenneth J; Ericson, Milton Nance; Baba, Justin S; Wilgen, John B; Evans, III, Boyd McCutchen

    2014-02-25

    Valve implant systems positionable within a flow passage, the systems having an inlet, an outlet, and a remotely activatable valve between the inlet and outlet, with the valves being operable to provide intermittent occlusion of the flow path. A remote field is applied to provide thermal or magnetic activation of the valves.

  18. Gate valve and motor-operator research findings

    International Nuclear Information System (INIS)

    Steele, R. Jr.; DeWall, K.G.; Watkins, J.C.; Russell, M.J.; Bramwell, D.

    1995-09-01

    This report provides an update on the valve research being sponsored by the US Nuclear Regulatory Commission (NRC) and conducted at the Idaho National Engineering Laboratory (INEL). The research addresses the need to provide assurance that motor-operated valves can perform their intended safety function, usually to open or close against specified (design basis) flow and pressure loads. This report describes several important developments: Two methods for estimating or bounding the design basis stem factor (in rising-stem valves), using data from tests less severe than design basis tests; a new correlation for evaluating the opening responses of gate valves and for predicting opening requirements; an extrapolation method that uses the results of a best effort flow test to estimate the design basis closing requirements of a gate valve that exhibits atypical responses (peak force occurs before flow isolation); and the extension of the original INEL closing correlation to include low- flow and low-pressure loads. The report also includes a general approach, presented in step-by-step format, for determining operating margins for rising-stem valves (gate valves and globe valves) as well as quarter-turn valves (ball valves and butterfly valves)

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

    International Nuclear Information System (INIS)

    Lowry, D.A.

    1990-01-01

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

  20. Scissor thrust valve actuator

    Science.gov (United States)

    DeWall, Kevin G.; Watkins, John C; Nitzel, Michael E.

    2006-08-29

    Apparatus for actuating a valve includes a support frame and at least one valve driving linkage arm, one end of which is rotatably connected to a valve stem of the valve and the other end of which is rotatably connected to a screw block. A motor connected to the frame is operatively connected to a motor driven shaft which is in threaded screw driving relationship with the screw block. The motor rotates the motor driven shaft which drives translational movement of the screw block which drives rotatable movement of the valve driving linkage arm which drives translational movement of the valve stem. The valve actuator may further include a sensory control element disposed in operative relationship with the valve stem, the sensory control element being adapted to provide control over the position of the valve stem by at least sensing the travel and/or position of the valve stem.

  1. Remotely handled and remotely operated valve, particularly for the hot part of radioactive plants. Fernhantierbare und fernbedienbare Armatur, insbesondere fuer den heissen Bereich radioaktiver Anlagen

    Energy Technology Data Exchange (ETDEWEB)

    Radovan, G.; Sandling, M.J.; Davidson, J.W.; Blaseck, K.; Hoffmeister, L.; Westendorf, H.

    1988-01-21

    The valve consists of a valve whose valve housing is built into a pipeline. The wear parts of the valve to be replaced, such as the valve body and valve seat, are combined into a replacement part. The replacement part and a clamp act together so that the replacement part is interlocked with the valve housing in the closed operating position. The exchange can be made by undoing a single central screw.

  2. Cellular regulation of the structure and function of aortic valves

    Directory of Open Access Journals (Sweden)

    Ismail El-Hamamsy

    2010-01-01

    Full Text Available The aortic valve was long considered a passive structure that opens and closes in response to changes in transvalvular pressure. Recent evidence suggests that the aortic valve performs highly sophisticated functions as a result of its unique microscopic structure. These functions allow it to adapt to its hemodynamic and mechanical environment. Understanding the cellular and molecular mechanisms involved in normal valve physiology is essential to elucidate the mechanisms behind valve disease. We here review the structure and developmental biology of aortic valves; we examine the role of its cellular parts in regulating its function and describe potential pathophysiological and clinical implications.

  3. International Conference on Fast Reactors and Related Fuel Cycles: Safe Technologies and Sustainable Scenarios (FR13), Paris – March 4-7, 2013: Closing Session. Summary of Sustainability of Advanced Fuel Cycles Panel Session II

    International Nuclear Information System (INIS)

    Cameron, R.

    2013-01-01

    Sustainability was discussed in terms of the social, environment and economic perspectives, which arise from the original Brundtland definition of sustainability. The panel presented their perspectives of the need to move towards a sustainable future, involving better use of uranium, reductions in high-level radioactive waste, safe, secure and economic operation of nuclear reactors and the fuel cycle. In all cases, it was considered that sustainability in the long-term must involve fast reactors and a closed nuclear fuel cycle, although both Korea and the IAEA pointed out that these are clearly national decisions and there will not be a single solution for all countries

  4. Characterization of a bioprosthetic bicuspid venous valve hemodynamics: implications for mechanism of valve dynamics.

    Science.gov (United States)

    Tien, W-H; Chen, H Y; Berwick, Z C; Krieger, J; Chambers, S; Dabiri, D; Kassab, G S

    2014-10-01

    Chronic venous insufficiency (CVI) of the lower extremities is a common clinical problem. Although bioprosthetic valves have been proposed to treat severe reflux, clinical success has been limited due to thrombosis and neointima overgrowth of the leaflets that is, in part, related to the hemodynamics of the valve. A bioprosthetic valve that mimics native valve hemodynamics is essential. A computational model of the prosthetic valve based on realistic geometry and mechanical properties was developed to simulate the interaction of valve structure (fluid-structure interaction, FSI) with the surrounding flow. The simulation results were validated by experiments of a bioprosthetic bicuspid venous valve using particle image velocimetry (PIV) with high spatial and temporal resolution in a pulse duplicator (PD). Flow velocity fields surrounding the valve leaflets were calculated from PIV measurements and comparisons to the FSI simulation results were made. Both the spatial and temporal results of the simulations and experiments were in agreement. The FSI prediction of the transition point from equilibrium phase to valve-closing phase had a 7% delay compared to the PD measurements, while the PIV measurements matched the PD exactly. FSI predictions of reversed flow were within 10% compared to PD measurements. Stagnation or stasis regions were observed in both simulations and experiments. The pressure differential across the valve and associated forces on the leaflets from simulations showed the valve mechanism to be pressure driven. The flow velocity simulations were highly consistent with the experimental results. The FSI simulation and force analysis showed that the valve closure mechanism is pressure driven under the test conditions. FSI simulation and PIV measurements demonstrated that the flow behind the leaflet was mostly stagnant and a potential source for thrombosis. The validated FSI simulations should enable future valve design optimizations that are needed for

  5. Thermostatic Radiator Valve Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Dentz, J. [Advanced Residential Integrated Energy Solutions Collaborative (ARIES), New York, NY (United States); Ansanelli, E. [Advanced Residential Integrated Energy Solutions Collaborative (ARIES), New York, NY (United States)

    2015-01-01

    A large stock of multifamily buildings in the Northeast and Midwest are heated by steam distribution systems. Losses from these systems are typically high and a significant number of apartments are overheated much of the time. Thermostatically controlled radiator valves (TRVs) are one potential strategy to combat this problem, but have not been widely accepted by the residential retrofit market. In this project, the ARIES team sought to better understand the current usage of TRVs by key market players in steam and hot water heating and to conduct limited experiments on the effectiveness of new and old TRVs as a means of controlling space temperatures and reducing heating fuel consumption. The project included a survey of industry professionals, a field experiment comparing old and new TRVs, and cost-benefit modeling analysis using BEopt™ (Building Energy Optimization software).

  6. A novel implantable glaucoma valve using ferrofluid.

    Directory of Open Access Journals (Sweden)

    Eleftherios I Paschalis

    Full Text Available PURPOSE: To present a novel design of an implantable glaucoma valve based on ferrofluidic nanoparticles and to compare it with a well-established FDA approved valve. SETTING: Massachusetts Eye & Ear Infirmary, Boston, USA. METHODS: A glaucoma valve was designed using soft lithography techniques utilizing a water-immiscible magnetic fluid (ferrofluid as a pressure-sensitive barrier to aqueous flow. Two rare earth micro magnets were used to calibrate the opening and closing pressure. In-vitro flow measurements were performed to characterize the valve and to compare it to Ahmed™ glaucoma valve. The reliability and predictability of the new valve was verified by pressure/flow measurements over a period of three months and X-ray diffraction (XRD analysis over a period of eight weeks. In vivo assessment was performed in three rabbits. RESULTS: In the in vitro experiments, the opening and closing pressures of the valve were 10 and 7 mmHg, respectively. The measured flow/pressure response was linearly proportional and reproducible over a period of three months (1.8 µl/min at 12 mmHg; 4.3 µl/min at 16 mmHg; 7.6 µl/min at 21 mmHg. X-ray diffraction analysis did not show oxidization of the ferrofluid when exposed to water or air. Preliminary in vivo results suggest that the valve is biocompatible and can control the intraocular pressure in rabbits. CONCLUSIONS: The proposed valve utilizes ferrofluid as passive, tunable constriction element to provide highly predictable opening and closing pressures while maintaining ocular tone. The ferrofluid maintained its magnetic properties in the aqueous environment and provided linear flow to pressure response. Our in-vitro tests showed reliable and reproducible results over a study period of three months. Preliminary in-vivo results were very promising and currently more thorough investigation of this device is underway.

  7. Propionibacterium acnes endophthalmitis in Ahmed glaucoma valve.

    Science.gov (United States)

    Gutiérrez-Díaz, E; Montero-Rodríguez, M; Mencía-Gutiérrez, E; Fernández-González, M C; Pérez-Blázquez, E

    2001-01-01

    To report a case of Propionibacterium acnes endophthalmitis in a patient with an Ahmed glaucoma valve. A nine-year-old boy with bilateral congenital glaucoma, with an Ahmed glaucoma valve implanted in the left eye, had recurrent conjunctival dehiscence and endophthalmitis. Vitreous cultures demonstrated the presence of Propionibacterium acnes. This is the first reported case of Propionibacterium acnes endophthalmitis in an Ahmed glaucoma valve and the second one in a glaucoma drainage device. We strongly recommend using a patch graft to prevent and treat tube exposure. Conjunctival grafts may be useful to close the conjunctiva when there is marked scarring to prevent patch exposure and melting or extrusion.

  8. Which valve is which?

    Directory of Open Access Journals (Sweden)

    Pravin Saxena

    2015-01-01

    Full Text Available A 25-year-old man presented with a history of breathlessness for the past 2 years. He had a history of operation for Tetralogy of Fallot at the age of 5 years and history suggestive of Rheumatic fever at the age of 7 years. On echocardiographic examination, all his heart valves were severely regurgitating. Morphologically, all the valves were irreparable. The ejection fraction was 35%. He underwent quadruple valve replacement. The aortic and mitral valves were replaced by metallic valve and the tricuspid and pulmonary by tissue valve.

  9. Neutronic and Isotopic Simulation of a Thorium-TRU's fuel Closed Cycle in a Lead Cooled ADS

    International Nuclear Information System (INIS)

    Garcia-Sanz, J. M.; Embid, M.; Fernandez, R.; Gonzalez, E. M.; Perez-Parra, A.

    2000-01-01

    The FACET group at CIEMAT is studying the properties and potentialities of several lead-cooled ADS designs for actinide and fission product transmutation. The main characteristics of these systems are the use of lead as primary coolant and moderator and fuels made by transuranics inside a thorium oxide matrix. The strategy assumed in this simulation implies that every discharge of the ADS will be reprocessed and would produce four waste streams: fission and activation products, remaining ''232 Th, produced ''233 U and remaining TRU's. The ''233 U is separated for other purposes; the remaining TRU are recovered altogether and mixed with the adequate amount of ''232 Th and fresh TRUs coming from LWR spent fuel. The simulations performed in this study have been focused primarily in the evolution of the fuel isotopic composition during and after each ADS burn-up cycle. (Author) 10 refs

  10. Electrically controlled fuel injection device for internal combustion engines with air quantity meter. Elektrisch gesteuerte Kraftstoffeinspritzeinrichtung fuer Brennkraftmaschinen mit Luftmengenmesser

    Energy Technology Data Exchange (ETDEWEB)

    Kraus, B; Soell, W

    1980-12-11

    The invention concerns an electrically controlled preferably intermittently working fuel injection device for internal combustion engines with a throttle valve, a solenoid operated injection valve and a transistor circuit, which supplies electrical pulses used to open the injection valve synchronously to the revolution of the crankshaft. The invention is characterized by the fact that an electrical control device is provided, which extends the individual opening pulses in thrust operation (with the throttle valve closed or nearly closed and with a working speed above the speed). The extension produced by the control device decreases from a value at about 20% for the maximum speed to a value of 0 for the tickover speed. Details of the transistor control are made clear by detailed circuit diagrams and 5 patent claims.

  11. Bioprosthetic Valve Fracture Improves the Hemodynamic Results of Valve-in-Valve Transcatheter Aortic Valve Replacement.

    Science.gov (United States)

    Chhatriwalla, Adnan K; Allen, Keith B; Saxon, John T; Cohen, David J; Aggarwal, Sanjeev; Hart, Anthony J; Baron, Suzanne J; Dvir, Danny; Borkon, A Michael

    2017-07-01

    Valve-in-valve (VIV) transcatheter aortic valve replacement (TAVR) may be less effective in small surgical valves because of patient/prosthesis mismatch. Bioprosthetic valve fracture (BVF) using a high-pressure balloon can be performed to facilitate VIV TAVR. We report data from 20 consecutive clinical cases in which BVF was successfully performed before or after VIV TAVR by inflation of a high-pressure balloon positioned across the valve ring during rapid ventricular pacing. Hemodynamic measurements and calculation of the valve effective orifice area were performed at baseline, immediately after VIV TAVR, and after BVF. BVF was successfully performed in 20 patients undergoing VIV TAVR with balloon-expandable (n=8) or self-expanding (n=12) transcatheter valves in Mitroflow, Carpentier-Edwards Perimount, Magna and Magna Ease, Biocor Epic and Biocor Epic Supra, and Mosaic surgical valves. Successful fracture was noted fluoroscopically when the waist of the balloon released and by a sudden drop in inflation pressure, often accompanied by an audible snap. BVF resulted in a reduction in the mean transvalvular gradient (from 20.5±7.4 to 6.7±3.7 mm Hg, P valve effective orifice area (from 1.0±0.4 to 1.8±0.6 cm 2 , P valves to facilitate VIV TAVR with either balloon-expandable or self-expanding transcatheter valves and results in reduced residual transvalvular gradients and increased valve effective orifice area. © 2017 American Heart Association, Inc.

  12. Analysis of Russian transition scenarios to innovative nuclear energy system based on thermal and fast reactors with closed nuclear fuel cycle using INPRO methodology

    International Nuclear Information System (INIS)

    Kagramanyan, V.S.; Poplavskaya, E.V.; Korobeynikov, V.V.; Kalashnikov, A.G.; Moseev, A.L.; Korobitsyn, V.E.; Andreeva-Andrievskaya, L.N.

    2011-01-01

    This paper presents the results of the analysis of modeling of Russian nuclear energy (NE) scenarios on the basis of thermal and fast reactors with closed nuclear fuel cycle (NFC). Modeling has been carried out with use of CYCLE code (SSC RF IPPE's tool) designed for analysis of Nuclear Energy System (NES) with closed NFC taking into account plutonium and minor actinides (MA) isotopic composition change during multi-recycling of fuel in fast reactors. When considering fast reactor introduction scenarios, one of important questions is to define optimal time for their introduction and related NFC's facilities. Analysis of the results obtained has been fulfilled using the key INPRO indicators for sustainable energy development. It was shown that a delay in fast reactor introduction led to serious ecological, social and finally economic risks for providing energy security and sustainable development of Russia in long-term prospects and loss of knowledge and experience in mastering innovative technologies of fast reactors and related nuclear fuel cycle. (author)

  13. New piezo driven gas inlet valve for fusion experiments

    International Nuclear Information System (INIS)

    Usselmann, E.; Hemmerich, J.L.; How, J.; Holland, D.; Orchard, J.; Winkel, T.; Schargitz, U.; Pocheim, N.

    1989-01-01

    The gas inlet valves used at the JET experiment are described and their performances are discussed. A new gas-valve development suitable to replace the existing valves at JET and for future use in large fusion experiments is presented. The new valve is equipped with a piezo-electric translator and has a dosing range of 0-800 mbarls -1 for D 2 . The operating mode of the valve is fail-safe closed with a leak-rate of ≤ 10 -9 mbarls -1 . The design, the test results and throughput values in dependence of filling pressure and control voltage are presented and experiences with the prototype valve as a new gas inlet valve for the JET operation are described

  14. Transient flow characteristics of a high speed rotary valve

    Science.gov (United States)

    Browning, Patrick H.

    Pressing economic and environmental concerns related to the performance of fossil fuel burning internal combustion engines have revitalized research in more efficient, cleaner burning combustion methods such as homogeneous charge compression ignition (HCCI). Although many variations of such engines now exist, several limiting factors have restrained the full potential of HCCI. A new method patented by West Virginia University (WVU) called Compression Ignition by Air Injection (CIBAI) may help broaden the range of effective HCCI operation. The CIBAI process is ideally facilitated by operating two synchronized piston-cylinders mounted head-to-head with one of the cylinders filled with a homogeneous mixture of air and fuel and the other cylinder filled with air. A specialized valve called the cylinder connecting valve (CCV) separates the two cylinders, opens just before reaching top dead center (TDC), and allows the injection air into the charge to achieve autoignition. The CCV remains open during the entire power stroke such that upon ignition the rapid pressure rise in the charge cylinder forces mass flow back through the CCV into the air-only cylinder. The limited mass transfer between the cylinders through the CCV limits the theoretical auto ignition timing capabilities and thermal efficiency of the CIBAI cycle. Research has been performed to: (1) Experimentally measure the transient behavior of a potential CCV design during valve opening between two chambers maintained at constant pressure and again at constant volume; (2) Develop a modified theoretical CCV mass flow model based upon the measured cold flow valve performance that is capable of predicting the operating conditions required for successful mixture autoignition; (3) Make recommendations for future CCV designs to maximize CIBAI combustion range. Results indicate that the modified-ball CCV design offers suitable transient flow qualities required for application to the CIBAI concept. Mass injection events

  15. Mitral Valve Prolapse

    Science.gov (United States)

    ... valve syndrome . What happens during MVP? Watch an animation of mitral valve prolapse When the heart pumps ( ... our brochures Popular Articles 1 Understanding Blood Pressure Readings 2 Sodium and Salt 3 Heart Attack Symptoms ...

  16. Problem: Mitral Valve Regurgitation

    Science.gov (United States)

    ... each time the left ventricle contracts. Watch an animation of mitral valve regurgitation A leaking mitral valve ... Not Alone Popular Articles 1 Understanding Blood Pressure Readings 2 Sodium and Salt 3 Heart Attack Symptoms ...

  17. Corrosion of valve metals

    International Nuclear Information System (INIS)

    Draley, J.E.

    1976-01-01

    A general survey related to the corrosion of valve metals or film-forming metals. The way these metals corrode with some general examples is described. Valve metals form relatively perfect oxide films with little breakdown or leakage when anodized

  18. Mitral valve surgery - open

    Science.gov (United States)

    ... Taking warfarin (Coumadin) References Otto CM, Bonow RO. Valvular heart disease. In: Mann DL, Zipes DP, Libby P, Bonow ... A.M. Editorial team. Heart Surgery Read more Heart Valve Diseases Read more Mitral Valve Prolapse Read more A. ...

  19. Mitral Valve Prolapse

    Science.gov (United States)

    Mitral valve prolapse (MVP) occurs when one of your heart's valves doesn't work properly. The flaps of the valve are "floppy" and ... to run in families. Most of the time, MVP doesn't cause any problems. Rarely, blood can ...

  20. Overflow control valve

    International Nuclear Information System (INIS)

    Kessinger, B.A.; Hundal, R.; Parlak, E.A.

    1982-01-01

    An overflow control valve for use in a liquid sodium coolant pump tank which can be remotely engaged with and disengaged from the pump tank wall to thereby permit valve removal. An actuating shaft for controlling the valve also has means for operating a sliding cylinder against a spring to retract the cylinder from sealing contact with the pump tank nozzle. (author)

  1. Fluid control valves

    International Nuclear Information System (INIS)

    Rankin, J.

    1980-01-01

    A fluid control valve is described in which it is not necessary to insert a hand or a tool into the housing to remove the valve seat. Such a valve is particularly suitable for the control of radioactive fluids since maintenance by remote control is possible. (UK)

  2. A remote control valve

    International Nuclear Information System (INIS)

    Cachard, Maurice de; Dumont, Maurice.

    1976-01-01

    This invention concerns a remote control valve for shutting off or distributing a fluid flowing at a high rate and low pressure. Among the different valves at present in use, electric valves are the most recommended for remote control but their reliability is uncertain and they soon become costly when large diameter valves are used. The valve described in this invention does away with this drawback owing to its simplicity and the small number of moving parts, this makes it particularly reliable. It mainly includes: a tubular body fitted with at least one side opening; at least one valve wedge for this opening, coaxial with the body, and mobile; a mobile piston integral with this wedge. Several valves to the specifications of this invention can be fitted in series (a shut-off valve can be used in conjunction with one or more distribution valves). The fitting and maintenance of the valve is very simple owing to its design. It can be fabricated in any material such as metals, alloys, plastics and concrete. The structure of the valve prevents the flowing fluid from coming into contact with the outside environment, thereby making it particularly suitable in the handling of dangerous or corrosive fluids. Finally, the opening and shutting of the valve occurs slowly, thereby doing away with the water hammer effect so frequent in large bore pipes [fr

  3. Simulant Development for Hanford Tank Farms Double Valve Isolation (DVI) Valves Testing

    Energy Technology Data Exchange (ETDEWEB)

    Wells, Beric E.

    2012-12-21

    Leakage testing of a representative sample of the safety-significant isolation valves for Double Valve Isolation (DVI) in an environment that simulates the abrasive characteristics of the Hanford Tank Farms Waste Transfer System during waste feed delivery to the Waste Treatment and Immobilization Plant (WTP) is to be conducted. The testing will consist of periodic leak performed on the DVI valves after prescribed numbers of valve cycles (open and close) in a simulated environment representative of the abrasive properties of the waste and the Waste Transfer System. The valve operations include exposure to cycling conditions that include gravity drain and flush operation following slurry transfer. The simulant test will establish the performance characteristics and verify compliance with the Documented Safety Analysis. Proper simulant development is essential to ensure that the critical process streams characteristics are represented, National Research Council report “Advice on the Department of Energy's Cleanup Technology Roadmap: Gaps and Bridges”

  4. Development of Overflow-Prevention Valve with Trigger Mechanism.

    Science.gov (United States)

    Ishino, Yuji; Mizuno, Takeshi; Takasaki, Masaya

    2016-09-01

    A new overflow-prevention valve for combustible fluid is developed which uses a trigger mechanism. Loading arms for combustible fluid are used for transferring oil from a tanker to tanks and vice versa. The loading arm has a valve for preventing overflow. Overflow- prevention valves cannot use any electric component to avoid combustion. Therefore, the valve must be constructed only by mechanical parts. The conventional overflow-prevention valve uses fluid and pneumatic forces. It consists of a sensor probe, a cylinder, a main valve for shutting off the fluid and a locking mechanism for holding an open state of the main valve. The proposed overflow-prevention valve uses the pressure due to the height difference between the fluid level of the tank and the sensor probe. However, the force of the cylinder produced by the pressure is too small to release the locking mechanism. Therefore, a trigger mechanism is introduced between the cylinder and the locking mechanism. The trigger mechanism produces sufficient force to release the locking mechanism and close the main valve when the height of fluid exceeds a threshold value. A trigger mechanism is designed and fabricated. The operation necessary for closing the main valve is conformed experimentally.

  5. Motor operated valves problems tests and simulations

    Energy Technology Data Exchange (ETDEWEB)

    Pinier, D.; Haas, J.L.

    1996-12-01

    An analysis of the two refusals of operation of the EAS recirculation shutoff valves enabled two distinct problems to be identified on the motorized valves: the calculation methods for the operating torques of valves in use in the power plants are not conservative enough, which results in the misadjustement of the torque limiters installed on their motorizations, the second problem concerns the pressure locking phenomenon: a number of valves may entrap a pressure exceeding the in-line pressure between the disks, which may cause a jamming of the valve. EDF has made the following approach to settle the first problem: determination of the friction coefficients and the efficiency of the valve and its actuator through general and specific tests and models, definition of a new calculation method. In order to solve the second problem, EDF has made the following operations: identification of the valves whose technology enables the pressure to be entrapped: the tests and numerical simulations carried out in the Research and Development Division confirm the possibility of a {open_quotes}boiler{close_quotes} effect: determination of the necessary modifications: development and testing of anti-boiler effect systems.

  6. Study on gasoline HCCI engine equipped with electromagnetic variable valve timing system; Untersuchung an einem HCCI Verbrennungsmotor mit elektromagnetisch variablem Ventiltriebsystem

    Energy Technology Data Exchange (ETDEWEB)

    Urata, Y.; Awasaka, M.; Takanashi, J.; Kimura, N. [Honda R and D Co., Ltd. (Japan)

    2004-07-01

    First, this paper describes a study on the technology behind the electromagnetic variable valve timing system. This system provides highly efficient and stable valve opening/closing control. At first, the main purposes of this mechanism were nonthrottling technology that is expected to a reduction in fuel consumption and improving the engine torque with optimal valve timing on stichomythic spark ignited engine. In resent years, increasing attention has been paid to a homogeneous charge compression ignition (HCCI). We also used this mechanism on HCCI study with controlling the amount of internal EGR and intake air. Schemes to extend the operational region of gasoline compression ignition were explored using single (optical) and 4-cylinder 4-stroke engines equipped with an electromagnetic variable valve timing system. This paper focuses mainly on the use of direct fuel injection devices (multi-hole and pintle types), exhaust gas recirculation (EGR) through valve timing, and their effects on the compression ignition operating ranges, and emissions. Also considered is charge boost HCCI using a mechanical supercharger. (orig.)

  7. Are anticoagulant independent mechanical valves within reach-fast prototype fabrication and in vitro testing of innovative bi-leaflet valve models.

    Science.gov (United States)

    Scotten, Lawrence N; Siegel, Rolland

    2015-08-01

    Exploration for causes of prosthetic valve thrombogenicity has frequently focused on forward or post-closure flow detail. In prior laboratory studies, we uncovered high amplitude flow velocities of short duration close to valve closure implying potential for substantial shear stress with subsequent initiation of blood coagulation pathways. This may be relevant to widely accepted clinical disparity between mechanical and tissue valves vis-à-vis thrombogenicity. With a series of prototype bi-leaflet mechanical valves, we attempt reduction of closure related velocities with the objective of identifying a prototype valve with thrombogenic potential similar to our tissue valve control. This iterative design approach may find application in preclinical assessment of valves for anticoagulation independence. Tested valves included: prototype mechanical bi-leaflet BVs (n=56), controls (n=2) and patented early prototype mechanicals (n=2) from other investigators. Pulsatile and quasi-steady flow systems were used for testing. Projected dynamic valve area (PDVA) was measured using previously described novel technology. Flow velocity over the open and closing periods was determined by volumetric flow rate/PDVA. For the closed valve interval, use was made of data obtained from quasi-steady back pressure/flow tests. Performance was ranked by a proposed thrombogenicity potential index (TPI) relative to tissue and mechanical control valves. Optimization of the prototype valve designs lead to a 3-D printed model (BV3D). For the mitral/aortic site, BV3D has lower TPI (1.10/1.47) relative to the control mechanical valve (3.44/3.93) and similar to the control tissue valve (ideal TPI ≤1.0). Using unique technology, rapid prototyping and thrombogenicity ranking, optimization of experimental valves for reduced thrombogenic potential was expedited and simplified. Innovative mechanical valve configurations were identified that merit consideration for further development which may bring

  8. Heavy gas valves

    Energy Technology Data Exchange (ETDEWEB)

    Steier, L [Vereinigte Armaturen Gesellschaft m.b.H., Mannheim (Germany, F.R.)

    1979-01-01

    Heavy gas valves must comply with special requirements. Apart from absolute safety in operation there are stringent requirements for material, sealing and ease of operation even in the most difficult conditions. Ball valves and single plate pipe gate valves lateral sealing rings have a dual, double sided sealing effect according to the GROVE sealing system. Single plate gate valves with lateral protective plates are suitable preferably for highly contaminated media. Soft sealing gate valves made of cast iron are used for low pressure applications.

  9. Relief valve testing study

    International Nuclear Information System (INIS)

    BROMM, R.D.

    2001-01-01

    Reclosing pressure-actuated valves, commonly called relief valves, are designed to relieve system pressure once it reaches the set point of the valve. They generally operate either proportional to the differential between their set pressure and the system pressure (gradual lift) or by rapidly opening fully when the set pressure is reached (pop action). A pop action valve allows the maximum fluid flow through the valve when the set pressure is reached. A gradual lift valve allows fluid flow in proportion to how much the system pressure has exceeded the set pressure of the valve (in the case of pressure relief) or has decreased below the set pressure (vacuum relief). These valves are used to protect systems from over and under pressurization. They are used on boilers, pressure vessels, piping systems and vacuum systems to prevent catastrophic failures of these systems, which can happen if they are under or over pressurized beyond the material tolerances. The construction of these valves ranges from extreme precision of less than a psi tolerance and a very short lifetime to extremely robust construction such as those used on historic railroad steam engines that are designed operate many times a day without changing their set pressure when the engines are operating. Relief valves can be designed to be immune to the effects of back pressure or to be vulnerable to it. Which type of valve to use depends upon the design requirements of the system

  10. Investigation of the thermal performance of a vertical two-phase closed thermosyphon as a passive cooling system for a nuclear reactor spent fuel storage pool

    Energy Technology Data Exchange (ETDEWEB)

    Kusuma, Mukhsinun Hadi; Putra, Nandy; Imawan, Ficky Augusta [Heat Transfer Laboratory, Department of Mechanical Engineering Universitas Indonesia, Kampus (Indonesia); Antariksawan, Anhar Riza [Centre for Nuclear Reactor Safety and Technology, National Nuclear Energy Agency of Indonesia (BATAN), Kawasan Puspiptek Serpong (Indonesia)

    2017-04-15

    The decay heat that is produced by nuclear reactor spent fuel must be cooled in a spent fuel storage pool. A wickless heat pipe or a vertical two-phase closed thermosyphon (TPCT) is used to remove this decay heat. The objective of this research is to investigate the thermal performance of a prototype model for a large-scale vertical TPCT as a passive cooling system for a nuclear research reactor spent fuel storage pool. An experimental investigation and numerical simulation using RELAP5/MOD 3.2 were used to investigate the TPCT thermal performance. The effects of the initial pressure, filling ratio, and heat load were analyzed. Demineralized water was used as the TPCT working fluid. The cooled water was circulated in the water jacket as a cooling system. The experimental results show that the best thermal performance was obtained at a thermal resistance of 0.22°C/W, the lowest initial pressure, a filling ratio of 60%, and a high evaporator heat load. The simulation model that was experimentally validated showed a pattern and trend line similar to those of the experiment and can be used to predict the heat transfer phenomena of TPCT with varying inputs.

  11. What caused the failures of the solenoid valve screws

    International Nuclear Information System (INIS)

    Vassallo, T.P.; Mumford, J.R.; Hossain, F.

    2001-01-01

    At Seabrook Station on May 5,1998 following a lengthy purge of the pressurizer steam space through Containment isolation sample valve 1-RC-FV-2830, the UL status light associated with this solenoid valve did not come on when the valve was closed from the plant's main control board. The UL status light is used to confirm valve closure position to satisfy the plant's Technical Specification requirements. The incorrect valve position indication on the main control board was initially believed to have resulted from excessive heat from a failed voltage control module that did not reduce the voltage to the valve's solenoid coil. This conclusion was based on a similar event that occurred in November of 1996. Follow-up in-plant testing of the valve determined that the voltage control module had not failed and was functioning satisfactorily. Subsequent investigations determined the root cause of the event to be excessive heat-up of the valve caused by high process fluid temperature and an excessively long purge of the pressurizer. The excessive heat-up of the valve from the high temperature process fluid weakened the magnetic field strength of the valve stem magnet to the extent that the UL status light reed switch would not actuate when the valve was closed. Since the voltage control module was tested and found to be functioning properly it was not replaced. Only the UL status light reed switch was replaced with a more sensitive reed that would respond better to a reduced magnetic field strength that results from a hot magnet. During reed switch replacement, three terminal block screws in the valve housing were found fractured and three other terminal block screws fractured during determination of the electrical conductors. This paper describes the initial plant event and ensuing laboratory tests and examinations that were performed to determine the root cause of the failure of the terminal block screws from the Containment isolation sample solenoid valve. (author)

  12. Leaky valves : New operation improves the heart's pumping action

    NARCIS (Netherlands)

    Pistecky, P.; Havlik, P.; Van Kasteren, J.

    2003-01-01

    The action of any pump will start to decline when the valves no longer close properly. The same goes for the heart, the pump that maintains the circulation in our vascular system. Consequently, a major field of focus of open heart surgery is the repair or replacement of heart valves. Petr Havl a

  13. Direct-heating solar-collector dump valve

    Science.gov (United States)

    Howikman, T. C.

    1977-01-01

    Five-port ganged valve isolates collector from primary load system pressure and drains collectors, allowing use of direct heating with all its advantages. Valve is opened and closed by same switch that controls pump or by temperature sensor set at O C, while providing direct dump option.

  14. Preliminary observations of gate valve flow interruption tests, Phase 2

    International Nuclear Information System (INIS)

    Steele, R. Jr.; DeWall, K.G.

    1990-01-01

    This paper presents preliminary observations from the US Nuclear Regulatory Commission/Idaho National Engineering Laboratory Flexible Wedge Gate Valve Qualification and Flow Interruption Test Program, Phase 2. The program investigated the ability of selected boiling water reactor (BWR) process line valves to perform their containment isolation function at high energy pipe break conditions and other more normal flow conditions. The fluid and valve operating responses were measured to provide information concerning valve and operator performance at various valve loadings so that the information could be used to assess typical nuclear industry motor operator sizing equations. Six valves were tested, three 6-in. isolation valves representative of those used in reactor water cleanup systems in BWRs and three 10-in. isolation valves representative of those used in BWR high pressure coolant injection (HPCI) steam lines. The concern with these normally open isolation valves is whether they will close in the event of a downstream pipe break outside of containment. The results of this testing will provide part of the technical insights for NRC efforts regarding Generic Issue 87 (GI-87), Failure of the HPCI Steam Line Without Isolation, which includes concerns about the uncertainties in gate valve motor operator sizing and torque switch settings for these BWR containment isolation valves. As of this writing, the Phase 2 test program has just been completed. Preliminary observations made in the field confirmed most of the results from the Phase 1 test program. All six valves closing in high energy water, high energy steam, and high pressure cold water require more force to close than would be calculated using the typical variables in the standard industry motor operator sizing equations

  15. Valve Corporation: Composing Internal Markets

    OpenAIRE

    Todd R. Zenger

    2015-01-01

    Discussions of the Valve Corporation are always enlightening. The skeptic wonders how much is rhetoric and recruiting ploy and how much is real. Is there clear evidence that this organizational design actually works – that it is efficient in this setting? While revenues per employee are quite remarkable, cause and effect are unclear. Is “boss-less-ness” the cause of high sales per employee or simply the result of high sales per employee, fueled from earlier success? The same question could be...

  16. Reduction of the suction losses through reed valves in hermetic reciprocating compressors using a magnet coil

    Science.gov (United States)

    Hopfgartner, J.; Posch, S.; Zuber, B.; Almbauer, R.; Krischan, K.; Stangl, S.

    2017-08-01

    Reed valves are widely used in hermetic reciprocating compressors and are responsible for a large part of the thermodynamic losses. Especially, the suction valve, which is opened nearly during the whole suction stroke, has a big potential for improvement. Usually, suction valves are opened only by vacuum created by the moving piston and should be closed before the compression stroke starts to avoid a reversed mass-flow through the valve. Therefore, the valves are prestressed, which results on the other hand in a higher flow resistance. In this work, a suction valve is investigated, which is not closed by the preload of the valve but by an electromagnetic coil located in the suction muffler neck. Shortly before the piston reaches its bottom dead centre, voltage is applied to the coil and a magnetic force is generated which pulls the valve shut. Thereby, the flow resistance through the valve can be reduced by changing the preload on the reed valve because it is no longer needed to close the valve. The investigation of this adapted valve and the electromagnetic coil is firstly done by numerical simulations including fluid structure interactions of the reed valves of a reciprocating compressor and secondly by experiments made on a calorimeter test bench.

  17. Worcester 1 Inch Solenoid-Actuated Gas-Operated VPS System Ball Valve

    International Nuclear Information System (INIS)

    VAN KATWIJK, C.

    2000-01-01

    1 inch Gas-operated full-port ball valve incorporates a solenoid and limit switches as integral parts of the actuator. The valve is normally open and fails safe to the closed position. The associated valve position switch is class GS

  18. Extrinsic mechanism obstructing the opening of a prosthetic mitral valve: an unusual case of suture entrapment.

    Science.gov (United States)

    Ozkan, Mehmet; Astarcioglu, Mehmet Ali; Karakoyun, Suleyman; Balkanay, Mehmet

    2012-02-01

    Obstruction to a prosthetic cardiac valve is a well-recognized complication of cardiac valve replacement. Malfunction of the mobile component of a prosthetic valve to open or close correctly may occur in consequence of intrinsic or extrinsic causes (thrombus, vegetation, entrapment of left ventricular myocardium, suture entanglement, and pannus formation) that may result prosthetic valve stenosis and/or insufficiency. In the case we report a 48-year-old female with valve dysfunction occurred early after surgery, as one valve leaflet was only able to partially open due to suture entrapment. © 2011, Wiley Periodicals, Inc.

  19. A self-regulating hydrogen generator for micro fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Moghaddam, Saeed; Pengwang, Eakkachai; Shannon, Mark A. [Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 West Green Street, Urbana, IL 61801 (United States); Masel, Richard I. [Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, 213 Roger Adams Lab, 600 S. Mathews, Urbana, IL 61801 (United States)

    2008-10-15

    The ever-increasing power demands and miniaturization of portable electronics, micro-sensors and actuators, and emerging technologies such as cognitive arthropods have created a significant interest in development of micro fuel cells. One of the major challenges in development of hydrogen micro fuel cells is the fabrication and integration of auxiliary systems for generating, regulating, and delivering hydrogen gas to the membrane electrode assembly (MEA). In this paper, we report the development of a hydrogen gas generator with a micro-scale control system that does not consume any power. The hydrogen generator consists of a hydride reactor and a water reservoir, with a regulating valve separating them. The regulating valve consists of a port from the water reservoir and a movable membrane with via holes that permit water to flow from the reservoir to the hydride reactor. Water flows towards the hydride reactor, but stops within the membrane via holes due to capillary forces. Water vapor then diffuses from the via holes into the hydride reactor resulting in generation of hydrogen gas. When the rate of hydrogen consumed by the MEA is lower than the generation rate, gas pressure builds up inside the hydride reactor, deflecting the membrane, closing the water regulator valve, until the pressure drops, whereby the valve reopens. We have integrated the self-regulating micro hydrogen generator to a MEA and successfully conducted fuel cell tests under varying load conditions. (author)

  20. Quantitative and radiological assessment of PYRO-SFR closed fuel cycle against direct disposal of spent nuclear fuel from Korean nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Muhammad Minhaj; Lee, Suhong; Cheong, Jaehak; Whang, Jooho [Kyunghee University, Seoul (Korea, Republic of)

    2016-12-15

    Calculations have been made to estimate the generation of SNF including Plutonium (Pu) and minor actinides (MAs) from PWR and PHWR NPPs by using the IAEA code Nuclear Fuel Cycle Simulation System (NFCSS) for the period of 2016, 2030 as 12 more NPPs will be added by the year 2029. In order to find the optimize option for SNF management through sustainable use of nuclear energy system and reduce the associated radiological risk, 4 scenarios to burnout the Pu and MAs are analyzed. Estimation for the amount of SNF including major radionuclides has made for the year of 2016, 2030, 2089 and 2109 with an approximate amount of 148,19.65MT, 248,34.6 MT, 41572.23 MT and 61272.24 MT of SNF will be generated respectively. Radioactivity and radiotoxicity is calculated in order to access the radiological risk in terms of ingestion. Four Transmutation strategies is predicted to make Korean NPPs sustainable by incorporating KALIMER-600 (Burner) reactor in Korean nuclear fleet with an approximate transmutation rate of 99.77%, 96.57%, 95.34% and 97.58% for MA only (scenario-1), (MA & Pu) scenario-2, scenario-3 (MA only till the year 2125) and scenario-4 MA & Pu till the year 2148) respectively.

  1. Guide to prosthetic cardiac valves

    International Nuclear Information System (INIS)

    Morse, D.; Steiner, R.M.; Fernandez, J.

    1985-01-01

    This book contains 10 chapters. Some of the chapter titles are: The development of artificial heart valves: Introduction and historical perspective; The radiology of prosthetic heart valves; The evaluation of patients for prosthetic valve implantation; Pathology of cardiac valve replacement; and Bioengineering of mechanical and biological heart valve substitutes

  2. Development of Proportional Pressure Control Valve for Hydraulic Braking Actuator of Automobile ABS

    Directory of Open Access Journals (Sweden)

    Che-Pin Chen

    2018-04-01

    Full Text Available This research developed a novel proportional pressure control valve for an automobile hydraulic braking actuator. It also analyzed and simulated solenoid force of the control valves, and the pressure relief capability test of electromagnetic thrust with the proportional valve body. Considering the high controllability and ease of production, the driver of this proportional valve was designed with a small volume and powerful solenoid force to control braking pressure and flow. Since the proportional valve can have closed-loop control, the proportional valve can replace a conventional solenoid valve in current brake actuators. With the proportional valve controlling braking and pressure relief mode, it can narrow the space of hydraulic braking actuator, and precisely control braking force to achieve safety objectives. Finally, the proposed novel proportional pressure control valve of an automobile hydraulic braking actuator was implemented and verified experimentally.

  3. Durability Tests of Ball Valve Prototype with Flowmeter Operation

    Science.gov (United States)

    Rogula, J.; Romanik, G.

    2018-02-01

    The results of the investigation of the prototypical ball valve are presented in this article. The innovation of the tested valve is a ball with a built-in measuring orifice. The valve has been subjected to durability tests. Leakage under three temperatures: ambient, -30°C and +100°C was analyzed. Sealing elements of the valve were tested for roughness and deviation of shape before and after the cycles of operation. Ball valve operation means cycles of open/close. It was planned to perform 1000 cycles at each temperature condition accordingly. Tests of the valve were performed under gas pressure equal to 10 MPa. The research was carried out under the Operational Program "Intelligent Development" (POIR 01.01.01-00-0013 / 15 "Development of devices for measurement of media flow on industrial trunk-lines".

  4. Early results of gate valve flow interruption blowdown tests

    International Nuclear Information System (INIS)

    DeWall, K.G.

    1988-01-01

    The preliminary results of the USNRC/INEL high-energy BWR line break flow interruption testing are presented. Two representative nuclear valve assemblies were cycled under design basis Reactor Water Cleanup pipe break conditions to provide input for the technical basis for resolving the Nuclear Regulatory Commission's Generic Issue 87. The effects of the blowdown hydraulic loadings on valve operability, especially valve closure stem forces, were studied. The blowdown tests showed that, given enough thrust, typical gate valves will close against the high flow resulting from a line break. The tests also showed that proper operator sizing depends on the correct identification of values for the sizing equation. Evidence exists that values used in the past may not be conservative for all valve applications. The tests showed that improper operator lock ring installation following test or maintenance can invalidate in-situ test results and prevent the valve from performing its design function. 2 refs., 12 figs., 2 tabs

  5. Intelligent Flow Control Valve

    Science.gov (United States)

    Kelley, Anthony R (Inventor)

    2015-01-01

    The present invention is an intelligent flow control valve which may be inserted into the flow coming out of a pipe and activated to provide a method to stop, measure, and meter flow coming from the open or possibly broken pipe. The intelligent flow control valve may be used to stop the flow while repairs are made. Once repairs have been made, the valve may be removed or used as a control valve to meter the amount of flow from inside the pipe. With the addition of instrumentation, the valve may also be used as a variable area flow meter and flow controller programmed based upon flowing conditions. With robotic additions, the valve may be configured to crawl into a desired pipe location, anchor itself, and activate flow control or metering remotely.

  6. Nuclear valves latest development

    International Nuclear Information System (INIS)

    Isaac, F.; Monier, M.

    1993-01-01

    In the frame of Nuclear Power Plant upgrade (Emergency Power Supply and Emergency Core Cooling), Westinghouse had to face a new valve design philosophy specially for motor operated valves. The valves have to been designed to resist any operating conditions, postulated accident or loss of control. The requirements for motor operated valves are listed and the selected model and related upgrading explained. As part of plant upgrade and valves replacement, Westinghouse has sponsored alternative hardfacing research programme. Two types of materials have been investigated: nickel base alloys and iron base alloys. Programme requirements and test results are given. A new globe valve model (On-Off or regulating) is described developed by Alsthom Velan permitting the seat replacement in less than 10 min. (Z.S.) 2 figs

  7. Low noise control valve

    International Nuclear Information System (INIS)

    Christie, R.S.

    1975-01-01

    Noise is one of the problems associated with the use of any type of control valve in systems involving the flow of fluids. The advent of OSHA standards has prompted control valve manufacturers to design valves with special trim to lower the sound pressure level to meet these standards. However, these levels are in some cases too high, particularly when a valve must be located in or near an area where people are working at tasks requiring a high degree of concentration. Such locations are found around and near research devices and in laboratory-office areas. This paper describes a type of fluid control device presently being used at PPL as a bypass control valve in deionized water systems and designed to reduce sound pressure levels considerably below OSHA standards. Details of the design and construction of this constant pressure drop variable flow control valve are contained in the text and are shown in photographs and drawings. Test data taken are included

  8. Aortic or Mitral Valve Replacement With the Biocor and Biocor Supra

    Science.gov (United States)

    2017-04-26

    Aortic Valve Insufficiency; Aortic Valve Regurgitation; Aortic Valve Stenosis; Aortic Valve Incompetence; Mitral Valve Insufficiency; Mitral Valve Regurgitation; Mitral Valve Stenosis; Mitral Valve Incompetence

  9. The Klinger hot gas double axial valve

    International Nuclear Information System (INIS)

    Kruschik, J.; Hiltgen, H.

    1984-01-01

    The Klinger hot gas valve is a medium controlled double axial valve with advanced design features and safety function. It was first proposed by Klinger early in 1976 for the PNP-Project as a containment shut-off for hot helium (918 deg. C and 42 bar), because a market research has shown that such a valve is not state of present techniques. In the first stage of development a feasibility study had to be made by detailed design, calculation and by basic experiments for key components in close collaboration with Interatom/GHT. This was the basis for further design, calculation, construction and experimental work for such a valve prototype within the new development contract. The stage of knowledge to that time revealed the following key priority development areas: Finite element stress analysis for the highly stressed high temperature main components; development of an insulation layout; Detailed experimental tests of functionally important structural components or units of the valve, partly at Klingers (gasstatic bearings, flexible metallic sealing element, aerodynamic and thermohydraulic tests), partly at Interatom (actuator unit and also gasstatic bearings), partly at HRB in Juelich (flexible metallic sealing system, aerodynamic and thermohydraulic tests); Design of a test valve for experimental work in the KVK (test circuit at Interatom) for evaluation of temperature distribution and reliability of operation; Design of a prototype and extensive testing in the KVK

  10. Solenoid hammer valve developed for quick-opening requirements

    Science.gov (United States)

    Wrench, E. H.

    1967-01-01

    Quick-opening lightweight solenoid hammer valve requires a low amount of electrical energy to open, and closes by the restoring action of the mechanical springs. This design should be applicable to many quick-opening requirements in fluid systems.

  11. Butterfly valves for seawater

    International Nuclear Information System (INIS)

    Yamanaka, Katsuto

    1991-01-01

    Recently in thermal and nuclear power stations and chemical plants which have become large capacity, large quantity of cooling water is required, and mostly seawater is utilized. In these cooling water systems, considering thermal efficiency and economy, the pipings become complex, and various control functions are demanded. For the purpose, the installation of shut-off valves and control valves for pipings is necessary. The various types of valves have been employed, and in particular, butterfly valves have many merits in their function, size, structure, operation, maintenance, usable period, price and so on. The corrosion behavior of seawater is complicated due to the pollution of seawater, therefore, the environment of the valves used for seawater became severe. The structure and the features of the butterfly valves for seawater, the change of the structure of the butterfly valves for seawater and the checkup of the butterfly valves for seawater are reported. The corrosion of metallic materials is complicatedly different due to the locating condition of plants, the state of pipings and the condition of use. The corrosion countermeasures for butterfly valves must be examined from the synthetic viewpoints. (K.I.)

  12. TFTR centralized torus interface valve control system

    International Nuclear Information System (INIS)

    Pearson, G.G.; Olsen, D.H.

    1983-01-01

    A system developed especially for the TFTR to monitor and control the interface between the vacuum vessel and associated diagnostics will be described in this paper. Diagnostics which must be connected to the machine vacuum are required to do so through a Torus Interface Valve (TIV). Two types of TIV's are used on TFTR. The first type is a non-latching valve which must be held in the opened position by a sustained OPEN command, returning automatically to the closed position when the OPEN command is removed. This type of TIV is used on all systems which never insert a probe into the vacuum vessel through the TIV. The second type of TIV is a latching valve which requires a momentary OPEN command to open and a momentary CLOSE command to close. Each TIV is linked to its own dedicated logic controller. Each logic controller is hardwired to the appropriate TIV OPEN/CLOSED limit switches, probe IN/OUT limit switches, TFTR vacuum vessel pressure setpoint switches, and diagnostic pressure setpoint switches. The logic controller can be configured for local (push-button) or remote (computer) control. Each controller has a uniquely coded keyswitch to determine the configuration. Whether under local or remote control, all OPEN and CLOSE commands must be approved by the TIV controller (TIVC). In the case of systems with probes, the controller must receive a positive indication that the probe is completely backed out before a CLOSE command will be transmitted from the TIVC to the TIV. Before a valve will be opened by a controller, the differential pressure across the valve must be within certain limits

  13. Fuel injection system for internal combustion engines. Kraftstoffeinspritzsystem fuer Brennkraftmaschinen

    Energy Technology Data Exchange (ETDEWEB)

    Hafner, U.

    1990-09-13

    A fuel injection system for an internal combustion engine is provided with a fuel supply line (13) and at least one electromagnetically actuated fuel injection valve (14) for apportioning a quantity of fuel for injection. A connection muzzle (24) coming from the valve body (23) juts into an opening (22) in the suction pipe (21) of the internal combustion engine. The end of the injection valve opposite the connecting muzzle (24) is connected with the fuel supply line via a fuel entry. The valve body (23) is enclosed by a casing (25) in order to provide the conditions required for a warm start. An annulus (31) extending over a large part of the axial length of the valve remains between the casing and the valve body (23). The annulus (31) communicates with the fuel flow through the fuel supply line (13) via an afflux and an efflux opening (32, 33) (Fig. 1).

  14. Diseases of the Tricuspid Valve

    Science.gov (United States)

    ... stenosis. Tricuspid Regurgitation Tricuspid regurgitation is also called tricuspid insufficiency or tricuspid incompetence. It means there is a ... require valve surgery. Tags: heart valves , tricuspid incompetence , ... tricuspid regurgitation , tricuspid stenosis , valve disease Related Links ...

  15. Modification and performance evaluation of a mono-valve engine

    Science.gov (United States)

    Behrens, Justin W.

    A four-stroke engine utilizing one tappet valve for both the intake and exhaust gas exchange processes has been built and evaluated. The engine operates under its own power, but has a reduced power capacity than the conventional 2-valve engine. The reduction in power is traced to higher than expected amounts of exhaust gases flowing back into the intake system. Design changes to the cylinder head will fix the back flow problems, but the future capacity of mono-valve engine technology cannot be estimated. The back flow of exhaust gases increases the exhaust gas recirculation (EGR) rate and deteriorates combustion. Intake pressure data shows the mono-valve engine requires an advanced intake valve closing (IVC) time to prevent back flow of charge air. A single actuation camshaft with advanced IVC was tested in the mono-valve engine, and was found to improve exhaust scavenging at TDC and nearly eliminated all charge air back flow at IVC. The optimum IVC timing is shown to be approximately 30 crank angle degrees after BDC. The mono-valve cylinder head utilizes a rotary valve positioned above the tappet valve. The open spaces inside the rotary valveand between the rotary valve and tappet valve represent a common volume that needs to be reduced in order to reduce the base EGR rate. Multiple rotary valve configurations were tested, and the size of the common volume was found to have no effect on back flow but a direct effect on the EGR rate and engine performance. The position of the rotary valve with respect to crank angle has a direct effect on the scavenging process. Optimum scavenging occurs when the intake port is opened just after TDC.

  16. Design And Analysis Of A Camless Valve Mechanism For I.C Engines Using Rotary Disc Valves

    Directory of Open Access Journals (Sweden)

    Vivek Jitendra Panchal

    2017-09-01

    Full Text Available It is the object of the presented paper to provide an electromechanical rotary valve actuating system for opening and closing valves of an internal combustion engine capable of separately controlling both the inlet and exhaust valve operations of each individual cylinder in a multi-cylinder engine. This indicates that only one valve will be required for each cylinder of the engine. Previously published versions of this concept require a separate valve for intake and exhaust in each cylinder. The system provides an alternative to the camshaft assembly in an attempt to overcome the limitations and inadequacies inevitably posed by a fully mechanical system. The prototype development is approached in a theoretical manner beginning with the conceptualization and design of a rotating disk with a notches and corresponding closure surfaces to open and close the flow path. The actuated disk and notch design is then refined and followed by the design of an inlet and exhaust manifold to correspond to the valve design and the theorizing and design of a sealing gasket. The rotating speed of the valve is determined by a general idling speed and can be varied to provide variable valve timing with the motor. The final assembly eliminates a majority of the moving parts currently used in camshaft systems like the cam camshaft rocker arm push rod and springs and results in a significantly lighter valve actuation system. By eliminating the translatory motion of valves the problem of valves slamming on the valve seats at high velocities is eliminated thus greatly reducing engine wear.

  17. Mechanisms of mechanical heart valve cavitation: investigation using a tilting disk valve model.

    Science.gov (United States)

    He, Z; Xi, B; Zhu, K; Hwang, N H

    2001-09-01

    The induction of mechanical heart valve (MHV) cavitation was investigated using a 27 mm Medtronic Hall (MH27) tilting disk valve. The MH27 valve was mounted in the mitral position of a simulating pulse flow system, and stroboscopic lighting used to visualize cavitation bubbles on the occluder inflow surface at the instant of valve closure. MHV cavitation was monitored using a digital camera with 0.04 mm/pixel resolution sufficient to render the tiny bubbles clearly visible on the computer monitor screen. Cavitation on MH27 valve was classified as five types according to the time, site and shape of the cavitation bubbles. Valve cavitation occurred at the instant of occluder impact with the valve seat at closing. The impact motion was subdivided into three temporal phases: (i) squeezing flow; (ii) elastic collision; and (iii) leaflet rebound. MHV cavitation caused by vortices was found to be initiated by the squeezing jet and/or by the transvalvular leakage jets. By using a tension wave which swept across the occluder surface immediately upon elastic impact, nuclei in the vortex core were expanded to form cavitation bubbles. Analysis of the shape and location of the cavitation bubbles permitted a better understanding of MHV cavitation mechanisms, based on the fluid dynamics of jet vortex and tension wave propagations.

  18. Group cross sections in the resolved resonance region calculated for a CANDU-PHW reactor operating on closed thorium-uranium and thorium-plutonium-uranium fuel cycles

    International Nuclear Information System (INIS)

    Hamel, D.; Wilkin, G.B.

    1979-09-01

    Group cross sections in the resolved resonance region are commonly computed for each nuclide independently of other resonance nuclides present in the fuel mixture. While this technique is usually entirely adequate for uranium fuel cycles, it is necessary to establish its legitimacy for closed thorium fuel cycles topped with fissile uranium or plutonium by analysis of a number of representative cases. At the same time cross sections originating from WIMS (Winfrith Improved Multigroup Scheme) calculations are compared with values computed in this study. In this context, particular attention is paid to the adequacy of the lower boundary for the WIMS resonance treatment. All calculations are based on heavy nuclide cross sections from the ENDF/B-IV data compilaton (Evaluated Nuclear Data File). Appreciable interaction effects have been determined for all nuclides except for 232 Th. In most cases, these are due to the strong 232 Th resonance doublet at 21.8 eV and 23.5 eV but some effects also result from resonances of 234 U (5.19 eV, 48.75 eV), 236 U (5.45 eV), 242 Pu (2.67 eV) and others. The influence of mutual interaction on the infinite lattice multiplicaton factor is very small in comparison to the effects of self-shielding. WIMS cross sections do not always compare well with the values computed in the study, but discrepancies are in most cases related to the different sources of data. Interaction effects are not explicitly taken into account in WIMS. Several nuclides ( 233 Pa, 233 U, 240 Pu, 242 Pu) show appreciable self-shielding below the WIMS resonance region and are therefore not treated adequately. The impact of these discrepancies on the multiplication factor is relatively small, however, because of error cancellation. (author)

  19. In situ laser measurements of CO and CH{sub 4} close to the surface of a burning single fuel particle

    Energy Technology Data Exchange (ETDEWEB)

    Lackner, M.; Totschnig, G.; Winter, F.; Maiorov, M.A.; Garbuzov, D.Z.; Connolly, J.C. [Vienna University of Technolgy, Vienna (Austria). Inst. of Chemical Engineering

    2002-07-01

    The combustion behaviour of three different fuels, bituminous coal, beech wood and fir wood, was investigated by monitoring the concentrations of CO, CH{sub 4}, CO{sub 2} and O{sub 2} during devolatilization and char combustion. Single fuel particles (4-6 mm diameter, 55 mm in length) were positioned in the freeboard of a laboratory-scale fluidized bed combustor. The superficial velocity was 0.3 m s{sup -1}. Tunable diode laser absorption spectroscopy was used to investigate in situ the concentration histories of the evolving species CO and CH{sub 4}. An InGaAsSb/AlGaAsSb diode laser was frequency tuned around 2.3/{mu}m at 300 Hz and traversed the reactor directly above the particle. This enabled the accurate measurement of species concentrations close to the surface of a burning particle. The influence of the oxygen partial pressure (5, 10, 15, 21 kPa), the bed temperature (700, 800, 900{sup o}C), the distance of the laser beam from the particle (4, 10, 21, 31 mm) and hence the residence time (12, 30, 60, 90 ms), the particle size (4, 6 {mu}m diameter) and the fuel type were investigated by independently changing these governing parameters. Conventional methods were deployed to determine CO, CO{sub 2} and O{sub 2} in the exhaust gas. The evolving CO could be tracked down to 12 ms after its generation. Biomass was found to produce four times as much CO as coal. The CO/CO{sub 2} ratio was found to be about five times higher for beech wood (a typical hardwood) than for fir wood (a typical softwood). The comparison of the in situ results with conventionally measured concentrations showed that the CO is normally underestimated during devolatilization and overestimated during char combustion. The discrepancy was attributed to more efficient degradation mechanisms for CO during devolatilization.

  20. Variable valve trains for internal combustion engines to control the valve height and the opening time; Variable Ventiltriebe fuer Verbrennungsmotoren zur Veraenderung von Ventilhub und Oeffnungsdauer

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Gunther [ThyssenKrupp Presta TecCenter AG, Eschen (Liechtenstein). R and D Projects

    2009-11-15

    The PDVC (Presta Delta Valve Control) continuously variable valve lift system is a mechanical system of valve control for achieving optimum performance and resulting in improved fuel consumption and reduced emissions across the entire operating range of the combustion engine. The continuous variability allows for engine load control by adjusting the valve height and therefore can also be used to replace the traditional throttle. The advantages are lower fuel consumption, reduction in emissions, quicker engine response, higher torque during the low speed range as well as more stable idling. The PSVC (Presta Shiftable Valve Control) is a 3 step shiftable valve lift system that offers the possibility to achieve a major part of these performance and associated consumption benefits with a simpler and therefore more cost-effective system. (orig.)

  1. Danfos: Thermostatic Radiator Valves

    DEFF Research Database (Denmark)

    Gregersen, Niels; Oliver, James; Hjorth, Poul G.

    2000-01-01

    This problem deals with modelling the flow through a typical Danfoss thermostatic radiator valve.Danfoss is able to employ Computational Fluid Dynamics (CFD) in calculations of the capacity of valves, but an experienced engineer can often by rules of thumb "guess" the capacity, with a precision...

  2. Isolating valve, especially in main-steam pipes of power plants

    International Nuclear Information System (INIS)

    Karpenko, A.N.

    1977-01-01

    The valve for PWRs and BWRs, with diameters up to 1.25 m, for temperatures from -180 0 C to about 600 0 C and pressures up to over 50 bar, is designed for high reliability and long useful life. Two circular valve discs are moved as isolating elements in their plane across the steam direction and brought before the valve seat within a valve chamber. Shortly before reaching this final position, each disc is rotated by a small amount about its axis. Only after reaching the final position a double-wedge, further pushed forward between both discs, produces the necessary contact pressure. By revolving and frictionless closing caking together at high stresses and temperature variation is prevented and permanent tightness assured. The valve body is moved in a cylinder, cast on the valve housing, by means of a stepped piston. Its larger diameter is guided in a second cylinder flanged on above. In the cover of the second cylinder a pilot valve is mounted being controlled over 2 parallel solenoid valves by means of compressed air. In normal operation process steam from the valve chamber serves to move the stepped piston with the valve chamber. On closing of a bore, connecting both cylinder spaces, by the pilot valve the main valve is opened. If the pilot valve is opened the steam through the connecting bore is acting on both piston stages and closing the main valve. On loss of steam (pipe break) or for testing purposes one or the other cylinder space over solenoid valves is acted upon by auxiliary energy or evacuated, the main valve thus being controlled. (HP) [de

  3. Bioprinting a cardiac valve.

    Science.gov (United States)

    Jana, Soumen; Lerman, Amir

    2015-12-01

    Heart valve tissue engineering could be a possible solution for the limitations of mechanical and biological prostheses, which are commonly used for heart valve replacement. In tissue engineering, cells are seeded into a 3-dimensional platform, termed the scaffold, to make the engineered tissue construct. However, mimicking the mechanical and spatial heterogeneity of a heart valve structure in a fabricated scaffold with uniform cell distribution is daunting when approached conventionally. Bioprinting is an emerging technique that can produce biological products containing matrix and cells, together or separately with morphological, structural and mechanical diversity. This advance increases the possibility of fabricating the structure of a heart valve in vitro and using it as a functional tissue construct for implantation. This review describes the use of bioprinting technology in heart valve tissue engineering. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Space Vehicle Valve System

    Science.gov (United States)

    Kelley, Anthony R. (Inventor); Lindner, Jeffrey L. (Inventor)

    2014-01-01

    The present invention is a space vehicle valve system which controls the internal pressure of a space vehicle and the flow rate of purged gases at a given internal pressure and aperture site. A plurality of quasi-unique variable dimension peaked valve structures cover the purge apertures on a space vehicle. Interchangeable sheet guards configured to cover valve apertures on the peaked valve structure contain a pressure-activated surface on the inner surface. Sheet guards move outwardly from the peaked valve structure when in structural contact with a purge gas stream flowing through the apertures on the space vehicle. Changing the properties of the sheet guards changes the response of the sheet guards at a given internal pressure, providing control of the flow rate at a given aperture site.

  5. Multiple-port valve

    International Nuclear Information System (INIS)

    Doody, T.J.

    1978-01-01

    A multiple-port valve assembly is designed to direct flow from a primary conduit into any one of a plurality of secondary conduits as well as to direct a reverse flow. The valve includes two mating hemispherical sockets that rotatably receive a spherical valve plug. The valve plug is attached to the primary conduit and includes diverging passageways from that conduit to a plurality of ports. Each of the ports is alignable with one or more of a plurality of secondary conduits fitting into one of the hemispherical sockets. The other hemispherical socket includes a slot for the primary conduit such that the conduit's motion along that slot with rotation of the spherical plug about various axes will position the valve-plug ports in respect to the secondary conduits

  6. Autonomous valve for detection of biopolymer degradation

    DEFF Research Database (Denmark)

    Keller, Stephan Urs; Noeth, Nadine-Nicole; Fetz, Stefanie

    2009-01-01

    We present a polymer microvalve that allows the detection of biopolymer degradation without the need of external energy. The valve is based on a polymer container filled with a colored marker solution and closed by a thin lid. This structure is covered by a film of poly(L-lactide) and degradation...... of the biopolymer triggers the release of the color which is detected visually. The autonomous valve has potential for the fast testing of biopolymer degradation under various environmental conditions or by specific enzymes....

  7. Experimental Investigation of a Multi-Cycle Single-Tube Pulse Detonation Rocket Engine with a Coaxial Rotary Valve

    Science.gov (United States)

    Matsuoka, Ken; Esumi, Motoki; Ikeguchi, Ken Bryan; Kasahara, Jiro; Matsuo, Akiko; Funaki, Ikkoh

    We developed a novel coaxial rotary valve for a multi-tube PDE. Since this single valve can supply three different gases (fuel, oxidizer and purge gas) into a combustor, the unification of the valve systems for three different gases is possible by using our newly designed valve. A PDRE system can be simple and lightweight by using this valve, and thus its thrust-weight ratio can be increased. We proposed the design of a multi-tube rotary-valved PDRE system by this rotary valve. Moreover, in preparation for a multi-tube rotary-valved PDRE, we carried out the multi-cycle operation experiment by the single-tube rotary-valved PDRE system. The combustion wave velocity was measured to confirm the operation of the PDRE system. Deflagration-to-detonation transition (DDT) was confirmed and DDT distance decreased under the condition of high operation frequency. In addition, a maximum operation frequency was 159 Hz.

  8. Flow induced vibration of the large-sized sodium valve for MONJU

    International Nuclear Information System (INIS)

    Sato, K.

    1977-01-01

    Measurements have been made on the hydraulic characteristics of the large-sized sodium valves in the hydraulic simulation test loop with water as fluid. The following three prototype sodium valves were tested; (1) 22-inch wedge gate type isolation valve, (2) 22-inch butterfly type isolation valve, and (3) 16-inch butterfly type control valve. In the test, accelerations of flow induced vibrations were measured as a function of flow velocity and disk position. The excitation mechanism of the vibrations is not fully interpreted in these tests due to the complexity of the phenomena, but the experimental results suggest that it closely depends on random pressure fluctuations near the valve disk and flow separation at the contracted cross section between the valve seat and the disk. The intensity of flow induced vibrations suddenly increases at a certain critical condition, which depends on the type of valve and is proportional to fluid velocity. (author)

  9. Flow induced vibration of the large-sized sodium valve for MONJU

    Energy Technology Data Exchange (ETDEWEB)

    Sato, K [Sodium Engineering Division, O-arai Engineering Centre, Power Reactor and Nuclear Fuel Development Corporation, Nariata-cho, O-arai Machi, Ibaraki-ken (Japan)

    1977-12-01

    Measurements have been made on the hydraulic characteristics of the large-sized sodium valves in the hydraulic simulation test loop with water as fluid. The following three prototype sodium valves were tested; (1) 22-inch wedge gate type isolation valve, (2) 22-inch butterfly type isolation valve, and (3) 16-inch butterfly type control valve. In the test, accelerations of flow induced vibrations were measured as a function of flow velocity and disk position. The excitation mechanism of the vibrations is not fully interpreted in these tests due to the complexity of the phenomena, but the experimental results suggest that it closely depends on random pressure fluctuations near the valve disk and flow separation at the contracted cross section between the valve seat and the disk. The intensity of flow induced vibrations suddenly increases at a certain critical condition, which depends on the type of valve and is proportional to fluid velocity. (author)

  10. Gate valve performance prediction

    International Nuclear Information System (INIS)

    Harrison, D.H.; Damerell, P.S.; Wang, J.K.; Kalsi, M.S.; Wolfe, K.J.

    1994-01-01

    The Electric Power Research Institute is carrying out a program to improve the performance prediction methods for motor-operated valves. As part of this program, an analytical method to predict the stem thrust required to stroke a gate valve has been developed and has been assessed against data from gate valve tests. The method accounts for the loads applied to the disc by fluid flow and for the detailed mechanical interaction of the stem, disc, guides, and seats. To support development of the method, two separate-effects test programs were carried out. One test program determined friction coefficients for contacts between gate valve parts by using material specimens in controlled environments. The other test program investigated the interaction of the stem, disc, guides, and seat using a special fixture with full-sized gate valve parts. The method has been assessed against flow-loop and in-plant test data. These tests include valve sizes from 3 to 18 in. and cover a considerable range of flow, temperature, and differential pressure. Stem thrust predictions for the method bound measured results. In some cases, the bounding predictions are substantially higher than the stem loads required for valve operation, as a result of the bounding nature of the friction coefficients in the method

  11. Modeling valve leakage

    International Nuclear Information System (INIS)

    Bell, S.R.; Rohrscheib, R.

    1994-01-01

    The American Society of Mechanical Engineers (ASME) Code requires individual valve leakage testing for Category A valves. Although the U.S. Nuclear Regulatory Commission (USNRC) has recognized that it is more appropriate to test containment isolation valves in groups, as allowed by 10 CFR 50, Appendix J, a utility seeking relief from these Code requirements must provide technical justification for the relief and establish a conservative alternate acceptance criteria. In order to provide technical justification for group testing of containment isolation valves, Illinois Power developed a calculation (model) for determining the size of a leakage pathway in a valve disc or seat for a given leakage rate. The model was verified experimentally by machining leakage pathways of known size and then measuring the leakage and comparing this value to the calculated value. For the range of values typical of leakage rate testing, the correlation between the experimental values and calculated values was quote good. Based upon these results, Illinois Power established a conservative acceptance criteria for all valves in the inservice testing (IST) program and was granted relief by the USNRC from the individual leakage testing requirements of the ASME Code. This paper presents the results of Illinois Power's work in the area of valve leakage rate testing

  12. HTR-PROTEUS Pebble Bed Experimental Program Cores 1, 1A, 2, and 3: Hexagonal Close Packing with a 1:2 Moderator-to-Fuel Pebble Ratio

    Energy Technology Data Exchange (ETDEWEB)

    John D. Bess; Barbara H. Dolphin; James W. Sterbentz; Luka Snoj; Igor Lengar; Oliver Köberl

    2013-03-01

    In its deployment as a pebble bed reactor (PBR) critical facility from 1992 to 1996, the PROTEUS facility was designated as HTR-PROTEUS. This experimental program was performed as part of an International Atomic Energy Agency (IAEA) Coordinated Research Project (CRP) on the Validation of Safety Related Physics Calculations for Low Enriched HTGRs. Within this project, critical experiments were conducted for graphite moderated LEU systems to determine core reactivity, flux and power profiles, reaction-rate ratios, the worth of control rods, both in-core and reflector based, the worth of burnable poisons, kinetic parameters, and the effects of moisture ingress on these parameters. Four benchmark experiments were evaluated in this report: Cores 1, 1A, 2, and 3. These core configurations represent the hexagonal close packing (HCP) configurations of the HTR-PROTEUS experiment with a moderator-to-fuel pebble ratio of 1:2. Core 1 represents the only configuration utilizing ZEBRA control rods. Cores 1A, 2, and 3 use withdrawable, hollow, stainless steel control rods. Cores 1 and 1A are similar except for the use of different control rods; Core 1A also has one less layer of pebbles (21 layers instead of 22). Core 2 retains the first 16 layers of pebbles from Cores 1 and 1A and has 16 layers of moderator pebbles stacked above the fueled layers. Core 3 retains the first 17 layers of pebbles but has polyethylene rods inserted between pebbles to simulate water ingress. The additional partial pebble layer (layer 18) for Core 3 was not included as it was used for core operations and not the reported critical configuration. Cores 1, 1A, 2, and 3 were determined to be acceptable benchmark experiments.

  13. HTR-PROTEUS Pebble Bed Experimental Program Cores 1, 1A, 2, and 3: Hexagonal Close Packing with a 1:2 Moderator-to-Fuel Pebble Ratio

    Energy Technology Data Exchange (ETDEWEB)

    John D. Bess; Barbara H. Dolphin; James W. Sterbentz; Luka Snoj; Igor Lengar; Oliver Köberl

    2012-03-01

    In its deployment as a pebble bed reactor (PBR) critical facility from 1992 to 1996, the PROTEUS facility was designated as HTR-PROTEUS. This experimental program was performed as part of an International Atomic Energy Agency (IAEA) Coordinated Research Project (CRP) on the Validation of Safety Related Physics Calculations for Low Enriched HTGRs. Within this project, critical experiments were conducted for graphite moderated LEU systems to determine core reactivity, flux and power profiles, reaction-rate ratios, the worth of control rods, both in-core and reflector based, the worth of burnable poisons, kinetic parameters, and the effects of moisture ingress on these parameters. Four benchmark experiments were evaluated in this report: Cores 1, 1A, 2, and 3. These core configurations represent the hexagonal close packing (HCP) configurations of the HTR-PROTEUS experiment with a moderator-to-fuel pebble ratio of 1:2. Core 1 represents the only configuration utilizing ZEBRA control rods. Cores 1A, 2, and 3 use withdrawable, hollow, stainless steel control rods. Cores 1 and 1A are similar except for the use of different control rods; Core 1A also has one less layer of pebbles (21 layers instead of 22). Core 2 retains the first 16 layers of pebbles from Cores 1 and 1A and has 16 layers of moderator pebbles stacked above the fueled layers. Core 3 retains the first 17 layers of pebbles but has polyethylene rods inserted between pebbles to simulate water ingress. The additional partial pebble layer (layer 18) for Core 3 was not included as it was used for core operations and not the reported critical configuration. Cores 1, 1A, 2, and 3 were determined to be acceptable benchmark experiments.

  14. CNG INJECTOR RESEARCH FOR DUAL FUEL ENGINE

    Directory of Open Access Journals (Sweden)

    Adam Majczak

    2017-03-01

    Full Text Available The article presents the tests results of the prototype design of hydraulically assisted injector, that is designed for gas supply into diesel engines. The construction of the injector allows for it positioning in the glow plug socket, so that the gas is injected directly into the combustion chamber. The cycle analysis of the four-cylinder Andoria ADCR engine with a capacity of 2.6 dm3 for different crankshaft rotational speeds allowed to determine the necessary time for fuel injection. Because of that, it was possible to determine the required mass flow rate of the injector, for replacing as much of the original fuel by gaseous fuel. To ensure a high value of flow inside the injector, supply pressure equal to 1 MPa was applied. High gas supply pressure requires high value of valve opening forces. For this purpose a injector with hydraulic control system, using a liquid under pressure for the opening process was designed. On the basis of air pressure measurements in the flow line after the injector, the analysis of opening and closing of the valve was made. Measurements of outflow mass of the injector were also carried out. The results showed that the designed injector meets the requirements necessary to supply ADCR engine by the CNG fuel.

  15. GIANT PROSTHETIC VALVE THROMBUS

    Directory of Open Access Journals (Sweden)

    Prashanth Kumar

    2015-04-01

    Full Text Available Mechanical prosthetic valves are predisposed to bleeding, thrombosis & thromboembolic complications. Overall incidence of thromboembolic complications is 1% per year who are on oral anticoagulants, whereas bleeding complications incidence is 0.5% to 6.6% per year. 1, 2 Minimization of Scylla of thromboembolic & Charybdis of bleeding complication needs a balancing act of optimal antithrombotic therapy. We are reporting a case of middle aged male patient with prosthetic mitral valve presenting in heart failure. Patient had discontinued anticoagulants, as he had subdural hematoma in the past. He presented to our institute with a giant prosthetic valve thrombus.

  16. Engines, fuels and pollution

    International Nuclear Information System (INIS)

    Salvi, G.

    1992-01-01

    The article points out the close relationship among engines, fuels and polluting emissions, and outlines an overall picture of future trends. The technical trade literature shows that diesel engines may undergo strong future development, due to their more favourable energy converting and less polluting characteristics. With regard to petrol injection engines, their improved construction under extremely close tolerances will result in a severe tightening-up of fuel specifications (with or without lead), so as to prevent the deposition of residues at the inlet (manifolds, injectors, valves, and combustion chamber), and their ensuing adverse effects on vehicle handling especially during the 'warm-up' stage. Recent checkups and tests run in the USA have evidenced that automotive engine-derived pollution in towns is in fact considerably more severe than that derived from mathematical models based on 'average emission factors' determined on a laboratory scale (roller bench tests, vaporization tests etc.). The entire body of regulations issued so far becomes questionable, and supplementary studies based on road-tests have been proposed. The paper's discussion is concluded with statistical data showing traffic pollution caused by VOCs (volatile organic compounds)

  17. Valve monitoring ITI-MOVATS

    International Nuclear Information System (INIS)

    Moureau, S.

    1993-01-01

    ITI-MOVATS provides a wide range of test devices to monitor the performance of valves: motor operated gate or globe valve, butterfly valve, air operated valve, and check valve. The ITI-MOVATS testing equipment is used in the following three areas: actuator setup/baseline testing, periodic/post-maintenance testing, and differential pressure testing. The parameters typically measured with the MOVATS diagnostic system as well as the devices used to measure them are described. (Z.S.)

  18. Bioprosthetic Valve Fracture to Facilitate Transcatheter Valve-in-Valve Implantation.

    Science.gov (United States)

    Allen, Keith B; Chhatriwalla, Adnan K; Cohen, David J; Saxon, John T; Aggarwal, Sanjeev; Hart, Anthony; Baron, Suzanne; Davis, J Russell; Pak, Alex F; Dvir, Danny; Borkon, A Michael

    2017-11-01

    Valve-in-valve transcatheter aortic valve replacement is less effective in small surgical bioprostheses. We evaluated the feasibility of bioprosthetic valve fracture with a high-pressure balloon to facilitate valve-in-valve transcatheter aortic valve replacement. In vitro bench testing on aortic tissue valves was performed on 19-mm and 21-mm Mitroflow (Sorin, Milan, Italy), Magna and Magna Ease (Edwards Lifesciences, Irvine, CA), Trifecta and Biocor Epic (St. Jude Medical, Minneapolis, MN), and Hancock II and Mosaic (Medtronic, Minneapolis, MN). High-pressure balloons Tru Dilation, Atlas Gold, and Dorado (C.R. Bard, Murray Hill, NJ) were used to determine which valves could be fractured and at what pressure fracture occurred. Mitroflow, Magna, Magna Ease, Mosaic, and Biocor Epic surgical valves were successfully fractured using high-pressures balloon 1 mm larger than the labeled valve size whereas Trifecta and Hancock II surgical valves could not be fractured. Only the internal valve frame was fractured, and the sewing cuff was never disrupted. Manufacturer's rated burst pressures for balloons were exceeded, with fracture pressures ranging from 8 to 24 atmospheres depending on the surgical valve. Testing further demonstrated that fracture facilitated the expansion of previously constrained, underexpanded transcatheter valves (both balloon and self-expanding) to the manufacturer's recommended size. Bench testing demonstrates that the frame of most, but not all, bioprosthetic surgical aortic valves can be fractured using high-pressure balloons. The safety of bioprosthetic valve fracture to optimize valve-in-valve transcatheter aortic valve replacement in small surgical valves requires further clinical investigation. Copyright © 2017 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  19. Impact of Chronic Rheumatic Valve Diseases on Large Vessels.

    Science.gov (United States)

    Altunbas, Gokhan; Yuce, Murat; Ozer, Hasan O; Davutoglu, Vedat; Ercan, Suleyman; Kizilkan, Nese; Bilici, Muhammet

    2016-01-01

    BACKGROUND AND AIM OF STUDY: Rheumatic valvular heart disease, which remains a common health problem in developing countries, has numerous consequences on the heart chambers and circulation. The study aim was to investigate the effects of chronic rheumatic valve disease on the diameters of the descending aorta (DA) and inferior vena cava (IVC). METHODS: A total of 88 patients with echocardiographically documented rheumatic valvular heart disease and 112 healthy controls were enrolled into the study. All patients underwent detailed echocardiographic examinations, while their height and body weight were recorded and adjusted to their body surface area. RESULTS: The most common involvement was mitral valve disease, followed by aortic valve disease and tricuspid valve disease. The mean diameter of the DA (indexed to BSA) was 1.79 ± 0.49 cm for patients and 1.53 ± 0.41 for controls (p Rheumatic valve disease, especially mitral stenosis, was closely related to remodeling of the great vessels.

  20. [Aortic valve-sparing root reconstruction in Marfan syndrome].

    Science.gov (United States)

    Ogino, H; Sasaki, H; Hanafusa, Y; Hirata, M; Numata, S; Ando, M; Yagihara, T; Kitamura, S

    2002-07-01

    The outcome of aortic valve-sparing root reconstruction in Marfan syndrome was reviewed. Thirteen patients with Marfan syndrome underwent aortic valve-sparing root reconstruction for annuloaortic ectasia or aortic root dissection between 1994 and 1999. The grade of preoperative aortic regurgitation was I in 4, II in 2, III in 5, IV in 2 patients. The procedures of aortic valve-sparing were reimplantation in 7 and remodeling in 5 patients. There was no hospital and late death. Recurrence of aortic regurgitation greater than moderate grade developed in 1 patient immediately after the surgery and in the other 4 patients in the late stage. One patient of them required aortic valve replacement for it. Aortic valve-sparing root reconstruction is applicable in Marfan patients, although the indication should be cautious. Close observation is needed for recurrence of aortic regurgitation.

  1. Integral isolation valve systems for loss of coolant accident protection

    Science.gov (United States)

    Kanuch, David J.; DiFilipo, Paul P.

    2018-03-20

    A nuclear reactor includes a nuclear reactor core comprising fissile material disposed in a reactor pressure vessel having vessel penetrations that exclusively carry flow into the nuclear reactor and at least one vessel penetration that carries flow out of the nuclear reactor. An integral isolation valve (IIV) system includes passive IIVs each comprising a check valve built into a forged flange and not including an actuator, and one or more active IIVs each comprising an active valve built into a forged flange and including an actuator. Each vessel penetration exclusively carrying flow into the nuclear reactor is protected by a passive IIV whose forged flange is directly connected to the vessel penetration. Each vessel penetration carrying flow out of the nuclear reactor is protected by an active IIV whose forged flange is directly connected to the vessel penetration. Each active valve may be a normally closed valve.

  2. Operating Temperatures of a Sodium-Cooled Exhaust Valve as Measured by a Thermocouple

    Science.gov (United States)

    Sanders, J. C.; Wilsted, H. D.; Mulcahy, B. A.

    1943-01-01

    A thermocouple was installed in the crown of a sodium-cooled exhaust valve. The valve was then tested in an air-cooled engine cylinder and valve temperatures under various engine operating conditions were determined. A temperature of 1337 F was observed at a fuel-air ratio of 0.064, a brake mean effective pressure of 179 pounds per square inch, and an engine speed of 2000 rpm. Fuel-air ratio was found to have a large influence on valve temperature, but cooling-air pressure and variation in spark advance had little effect. An increase in engine power by change of speed or mean effective pressure increased the valve temperature. It was found that the temperature of the rear spark-plug bushing was not a satisfactory indication of the temperature of the exhaust valve.

  3. Optimal Control of the Valve Based on Traveling Wave Method in the Water Hammer Process

    Science.gov (United States)

    Cao, H. Z.; Wang, F.; Feng, J. L.; Tan, H. P.

    2011-09-01

    Valve regulation is an effective method for process control during the water hammer. The principle of d'Alembert traveling wave theory was used in this paper to construct the exact analytical solution of the water hammer, and the optimal speed law of the valve that can reduce the water hammer pressure in the maximum extent was obtained. Combining this law with the valve characteristic curve, the principle corresponding to the valve opening changing with time was obtained, which can be used to guide the process of valve closing and to reduce the water hammer pressure in the maximum extent.

  4. Fuel assembly

    International Nuclear Information System (INIS)

    Yokota, Tokunobu.

    1990-01-01

    A fuel assembly used in a FBR type nuclear reactor comprises a plurality of fuel rods and a moderator guide member (water rod). A moderator exit opening/closing mechanism is formed at the upper portion of the moderator guide member for opening and closing a moderator exit. In the initial fuel charging operation cycle to the reactor, the moderator exit is closed by the moderator exit opening/closing mechanism. Then, voids are accumulated at the inner upper portion of the moderator guide member to harden spectrum and a great amount of plutonium is generated and accumulated in the fuel assembly. Further, in the fuel re-charging operation cycle, the moderator guide member is used having the moderator exit opened. In this case, voids are discharged from the moderator guide member to decrease the ratio, and the plutonium accumulated in the initial charging operation cycle is burnt. In this way, the fuel economy can be improved. (I.N.)

  5. Pulmonary valve stenosis

    Science.gov (United States)

    ... surgery - discharge Images Heart valves References Carabello BA. Valvular heart disease. In: Goldman L, Schafer AI, eds. Goldman's Cecil ... Saunders; 2016:chap 69. Otto CM, Bownow RO. Valvular heart disease. In: Mann DL, Zipes DP, Libby P, Bonow ...

  6. Mitral valve regurgitation

    Science.gov (United States)

    ... and dentist if you have a history of heart valve disease or congenital heart disease before treatment. Some people ... the middle Heart, front view References Carabello BA. Valvular heart disease. In: Goldman L, Schafer AI, eds. Goldman-Cecil ...

  7. Aortic Valve Disease

    Science.gov (United States)

    ... team will discuss with you the advantages and disadvantages of both valve types. Regardless of which type ... Diagnosis and Treatment Options Recovery Questions for Your Doctor Will my condition ever get better without treatment? ...

  8. Dry product valve

    International Nuclear Information System (INIS)

    Greaves, James D.

    1984-01-01

    This invention provides a system for delivering particulate radioactive or other toxic wastes to a container in which they can be solidified. The system includes a set of valves that prevent the escape of dusty materials to the atmosphere

  9. Ball check valve

    International Nuclear Information System (INIS)

    Bevilacqua, F.

    1978-01-01

    A pressurized nuclear reactor having an instrument assembly sheathed in a metallic tube which is extended vertically upward into the reactor core by traversing a metallic guide tube which is welded to the wall of the vessel is described. Sensors in each instrument assembly are connected to instruments outside the vessel to manifest the conditions within the core. Each instrument assembly probe is moved into position within a metallic guide channel. The guide channel penetrates the wall of the vessel and forms part of the barrier to the environment within the pressure vessel. Each channel includes a ball check valve which is opened by the instrument assembly probe when the probe passes through the valve. A ball valve element is moved from its seat by the probe to a position lateral of the bore of the channel and is guided to its seat along a sloped path within the valve body when the probe is removed. 5 claims, 3 figures

  10. Isolation valve control device for nuclear power plant

    International Nuclear Information System (INIS)

    Yukinori, Shigeru.

    1990-01-01

    The present invention provides an isolation valve control device for detecting pipeline rupture accidents in a BWR type nuclear power plant at an early stage to close an isolation valve thereby reducing the amout of radioactivity released to the circumstance. That is, isolation valves are disposed in the pipeline for each of the systems in the nuclear power plant and flow ratemeters are disposed to at least two positions in each of the pipelines. If a meaningful difference is shown for the measured values by these flow ratemeters, the isolation valve is closed. In this way, if pipeline rupture such as leak before break (LBB) is caused to a portion of a system pipelines, the measured value from the flow ratemeters at the downstream of the pipeline is lowered. Accordingly, when a meaningful difference is formed between the value of the flow ratematers at the upstream and the downstream, occurrence of pipe rutpture between both of the flow ratemeters can be detected. As a result, the isolation valves of the system can be closed. According to the present invention, it is possible to detect the pipeline rupture at an early stage irrespective of the kind of the systems, diameter of the pipelines and the magnitude of the ruptured area, and the isolation valve can be closed. (I.S.)

  11. Effects of pressure and temperature on gate valve unwedging

    Energy Technology Data Exchange (ETDEWEB)

    Damerell, P.S.; Harrison, D.H.; Hayes, P.W.; Simons, J.W.; Walker, T.A.

    1996-12-01

    The stem thrust required to unwedge a gate valve is influenced by the pressure and temperature when the valve is closed and by the changes in these conditions between closure and opening. {open_quotes}Pressure locking{close_quotes} and {open_quotes}thermal binding{close_quotes} refer to situations where pressure and temperature effects cause the unwedging load to be much higher than normal. A model of these phenomena has been developed. Wedging (closure) is modeled as developing an {open_quotes}interference{close_quotes} between the disk and its seat rings in the valve. The effects of pressure and temperature are analyzed to determine the change in this disk-to-seat {open_quotes}interference{close_quotes}. Flexibilities, of the disk, body, stem and yoke strongly influence the unwedging thrust. Calculations and limited comparisons to data have been performed for a range of valve designs and scenarios. Pressure changes can increase the unwedging load when there is either a uniform pressure decrease, or a situation where the bonnet pressure exceeds the pressures in the adjacent piping. Temperature changes can increase the unwedging load when: (1) valve closure at elevated system temperature produces a delayed stem expansion, (2) a temperature increase after closure produces a bonnet pressure increase, or (3) a temperature change after closure produces an increase in the disk-to-seat {open_quotes}interference{close_quotes} or disk-to-seat friction.

  12. 40 CFR 63.1015 - Closed vent systems and control devices; or emissions routed to a fuel gas system or process.

    Science.gov (United States)

    2010-07-01

    ... devices; or emissions routed to a fuel gas system or process. 63.1015 Section 63.1015 Protection of... fuel gas system or process. (a) Compliance schedule. The owner or operator shall comply with this... emissions from equipment leaks to a fuel gas system or process shall comply with the provisions of subpart...

  13. Classification of heart valve condition using acoustic measurements

    Energy Technology Data Exchange (ETDEWEB)

    Clark, G. [Lawrence Livermore National Lab., CA (United States)

    1994-11-15

    Prosthetic heart valves and the many great strides in valve design have been responsible for extending the life spans of many people with serious heart conditions. Even though the prosthetic valves are extremely reliable, they are eventually susceptible to long-term fatigue and structural failure effects expected from mechanical devices operating over long periods of time. The purpose of our work is to classify the condition of in vivo Bjork-Shiley Convexo-Concave (BSCC) heart valves by processing acoustic measurements of heart valve sounds. The structural failures of interest for Bscc valves is called single leg separation (SLS). SLS can occur if the outlet strut cracks and separates from the main structure of the valve. We measure acoustic opening and closing sounds (waveforms) using high sensitivity contact microphones on the patient`s thorax. For our analysis, we focus our processing and classification efforts on the opening sounds because they yield direct information about outlet strut condition with minimal distortion caused by energy radiated from the valve disc.

  14. Fast valve for the National Synchrotron Light Source

    International Nuclear Information System (INIS)

    Oversluizen, T.

    1981-01-01

    A prototype fast closing, all metal, UHV-compatible valve has been built to protect the NSLS storage rings from sudden vacuum failures which may occur in the experimental beamlines. When triggered, an area of 10 x 140 mm is covered by a spring-driven, guillotine type blade, which forms a high impedance to the inrushing gas. This fast closure assures the protection of the ring vacuum from contamination before the slower UHV valve can be sealed off. Closing times on the order of 3 to 5 msec have been measured. The valve is triggered by a commercial solenoid, powered by a 16,800 μF capacitor bank at 100 volts. Because the valve is situated in a high radiation area, it is remotely resettable

  15. Modal-Based Design Improvement of a Butterfly Valve Disc

    Directory of Open Access Journals (Sweden)

    Marius Draghiciu

    2017-11-01

    Full Text Available The dynamic behaviour control of a butterfly valve is important because, when one of the valve disc natural frequency is close to the frequency of vortex shedding, which appears when the valve is fully open or partially closed, resonance may appear and vibration with significant amplitudes is generated. This paper presents an example by how the design of a butterfly valve disc can be improved by using a modal analysis performed by means of the finite element method. For this purpose, the research reveals the way in which the natural frequencies of the disc can be modified by applying stiffening ribs or changing the dimensions, respective the position of these ribs.

  16. Assessment of Nuclear Energy Systems Based on a Closed Nuclear Fuel Cycle with Fast Reactors. A report of the International Project on Innovative Nuclear Reactors and Fuel Cycles (INPRO)

    International Nuclear Information System (INIS)

    2010-01-01

    A Joint Study was started in 2005 and completed in 2007 within the International Project on Innovative Nuclear Reactors and Fuel Cycles (INPRO). Canada, China, France, India, Japan, the Republic of Korea, the Russian Federation, and Ukraine participated in this study. The objectives were to assess a nuclear energy system based on a closed fuel cycle (CNFC) with fast reactors (FR) regarding its sustainability, determine milestones for the nuclear energy system deployment, and establish frameworks for, and areas of, collaborative R and D work. The assessment was carried out in accordance with the requirements of INPRO methodology and guiding documents of the Joint Study developed and approved by the participating parties (Canada and Ukraine participated in the discussions during the Joint Study, but did not contribute to the assessments themselves). The Joint Study was implemented in steps. In its first step, nominated experts, during the course of extensive discussions, analyzed the country/region/world context data; discussed national and global scenarios of introduction of the CNFC-FR systems; identified technologies suitable for the INS; and arrived at a broad definition of a common CNFC-FR system. In the second step, the participants of the study examined characteristics of CNFC-FR systems for compliance with criteria of sustainability developed in the INPRO methodology in the area of economics, safety, environment, waste management, proliferation resistance, and infrastructure. The results of the study were submitted to and endorsed by the INPRO Steering Committee in meetings held in Vienna 2005 - 2007. The authors of the Joint Study report highly appreciate the valuable comments provided by delegates of the INPRO Steering Committee meetings as well as the advice and assistance of the other experts. Due to the length of the Joint Study report, a summary of the results was produced, which is the content of this publication. The full text of the Joint Study

  17. Assessment of Nuclear Energy Systems based on a Closed Nuclear Fuel Cycle with Fast Reactors. A Report of the International Project on Innovative Nuclear Reactors and Fuel Cycles (INPRO)

    International Nuclear Information System (INIS)

    2012-09-01

    A Joint Study was started in 2005 and completed in 2007 within the International Project on Innovative Nuclear Reactors and Fuel Cycles (INPRO). Canada, China, France, India, Japan, the Republic of Korea, the Russian Federation, and Ukraine participated in this study. The objectives were to assess a nuclear energy system based on a closed fuel cycle (CNFC) with fast reactors (FR) regarding its sustainability, determine milestones for the nuclear energy system deployment, and establish frameworks for, and areas of, collaborative R and D work. The assessment was carried out in accordance with requirements of INPRO methodology and guiding documents of the Joint Study developed and approved by the participating parties (Canada and Ukraine participated in the discussions during the Joint Study but did not contribute to the assessments themselves). The Joint Study was implemented in steps. In its first step, nominated experts in course of extensive discussions analyzed the country/region/world context data, discussed national and global scenarios of introduction of the INS CNFC-FR, identified technologies suitable for the INS, and arrived at a broad definition of a common INS CNFC-FR. In the second step, the participants of the study examined characteristics of INS CNFC-FR for compliance with criteria of sustainability developed in the INPRO methodology in the domain of economics, safety, environment, waste management, proliferation resistance, physical protection and infrastructure. The results of the study were submitted to and endorsed by the INPRO Steering Committee meetings held in Vienna 2005-2007. The authors of the report highly appreciate the valuable comments provided by delegates of INPRO Steering Committee meetings as well as the advice and assistance of the other experts. Due to the length of the Joint Study report a summary of the results was produced, which was published as a hard copy. The full text of the Joint Study report is available on the CD

  18. 14 CFR 29.979 - Pressure refueling and fueling provisions below fuel level.

    Science.gov (United States)

    2010-01-01

    ..., DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Fuel System § 29.979 Pressure refueling and fueling provisions below fuel level. (a) Each fueling connection... from that tank in case of malfunction of the fuel entry valve. (b) For systems intended for pressure...

  19. Classification of the radiological morphology of the mitral valve

    International Nuclear Information System (INIS)

    Spindola-Franco, H.; Bjork, L.; Adams, D.F.; Abrams, H.L.

    1980-01-01

    The morphology of the mitral valve apparatus was assessed on 100 normal left ventriculograms. Four distinct types of mitral valve were identified according to the position of the mitral fulcrum (the point of attachment of the leaflets to the annulus) and the configuration of the adjacent left ventricular wall (left ventricular fornix) during diastole. Types I and II closely simulated prolapse of the mitral valve (pseudoprolapse) in the right anterior oblique projection during the ejection period. Measurements showed that contraction of the ventricle failed to reduce the diameter of the mitral annulus in 26 per cent of normal left ventricles. (U.K.)

  20. Fixation and mounting of porcine aortic valves for use in mock circuits.

    Science.gov (United States)

    Schlöglhofer, Thomas; Aigner, Philipp; Stoiber, Martin; Schima, Heinrich

    2013-10-01

    Investigations of the circulatory system in vitro use mock circuits that require valves to mimic the cardiac situation. Whereas mechanical valves increase water hammer effects due to inherent stiffness and do not allow the use of pressure lines or catheters, bioprosthetic valves are expensive and of limited durability in test fluids. Therefore, we developed a cheap, fast, alternative method to mount valves obtained from the slaughterhouse in mock circuits. Porcine aortic roots were obtained from the abattoir and used either in native condition or after fixation. Fixation was performed at a constant retrograde pressure to ensure closed valve position. Fixation time was 4 h in a 0.5%-glutaraldehyde phosphate buffer. The fixed valves were molded into a modular mock circulation connector using a fast curing silicone. Valve functionality was evaluated in a pulsatile setting (cardiac output = 4.7 l/min, heart rate = 80 beats/min) and compared before and after fixation. Leaflet motion was recorded with a high-speed camera and valve insufficiency was quantified by leakage flow under steady pressure application (80 mmHg). Under physiological conditions the aortic valves showed almost equal leaflet motion in native and fixed conditions. However, the leaflets of the native valves showed lower stiffness and more fluttering during systole than the fixed specimens. Under retrograde pressure, fresh and fixed valves showed small leakage flows of <30 ml/min. The new mounting and fixation procedure is a fast method to fabricate low cost biologic valves for the use in mock circuits.

  1. Transcatheter Aortic Valve Replacement for Degenerative Bioprosthetic Surgical Valves

    DEFF Research Database (Denmark)

    Dvir, Danny; Webb, John; Brecker, Stephen

    2012-01-01

    Transcatheter aortic valve-in-valve implantation is an emerging therapeutic alternative for patients with a failed surgical bioprosthesis and may obviate the need for reoperation. We evaluated the clinical results of this technique using a large, worldwide registry....

  2. NRC valve performance test program - check valve testing

    International Nuclear Information System (INIS)

    Jeanmougin, N.M.

    1987-01-01

    The Valve Performance Test Program addresses the current requirements for testing of pressure isolation valves (PIVs) in light water reactors. Leak rate monitoring is the current method used by operating commercial power plants to survey the condition of their PIVs. ETEC testing of three check valves (4-inch, 6-inch, and 12-inch nominal diameters) indicates that leak rate testing is not a reliable method for detecting impending valve failure. Acoustic emission monitoring of check valves shows promise as a method of detecting loosened internals damage. Future efforts will focus on evaluation of acoustic emission monitoring as a technique for determining check valve condition. Three gate valves also will be tested to evaluate whether the check valve results are applicable to gate type PIVs

  3. Pressure locking and thermal binding of gate valves

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, E.M.

    1996-12-01

    Pressure locking and thermal binding represent potential common mode failure mechanisms that can cause safety-related power-operated gate valves to fail in the closed position, thus rendering redundant safety-related systems incapable of performing their safety functions. Supplement 6 to Generic Letter 89-10, {open_quotes}Safety-Related Motor-Operated Gate Valve Testing and Surveillance,{close_quotes} provided an acceptable approach to addressing pressure locking and thermal binding of gate valves. More recently, the NRC has issued Generic Letter 95-07, {open_quotes}Pressure Locking and Thermal Binding of Safety-Related Power-Operated Gate Valves,{close_quotes} to request that licensees take certain actions to ensure that safety-related power-operated gate valves that are susceptible to pressure locking or thermal binding are capable of performing their safety functions within the current licensing bases. Over the past two years, several plants in Region I determined that valves in certain systems were potentially susceptible to pressure locking and thermal binding, and have taken various corrective actions. The NRC Region I Systems Engineering Branch has been actively involved in the inspection of licensee actions in response to the pressure locking and thermal binding issue. Region I continues to maintain an active involvement in this area, including participation with the Office of Nuclear Reactor Regulation in reviewing licensee responses to Generic Letter 95-07.

  4. System for remotely servicing a top loading captive ball valve

    International Nuclear Information System (INIS)

    Berry, S.M.; Porter, M.L.

    1996-01-01

    An attachment for facilitating servicing of a valve is disclosed including: an assembly composed of a valve seat defining a flow path, a flow control member movable relative to the valve seat for blocking or unblocking the valve seat, and a control device including a stem coupled to the flow control member and operable for moving the flow control member relative to the valve se housing for receiving the assembly, the housing having an opening via which the assembly can be removed from, and installed in, the housing, and the housing having a plurality of threaded studs which surround the opening and project away from the housing; a valve housing cover for closing and sealing the opening in the housing, the cover having a first bore for passage of the stem of the control device when the assembly is installed in the housing and a plurality of second bores each located for passage of a respective stud when the cover closes the opening in the housing. A plurality of threaded nuts are engageable with the studs for securing the cover to the housing when the cover closes the opening in the housing, wherein the attachment comprises: a plurality of nut guide devices removable from the housing and each operatively associated with a respective stud for retaining a respective nut and guiding the respective nut into alignment with the respective stud to enable the respective nut to be rotated into engagement with the respective stud; and aligning the nut guide devices with the studs. 7 figs

  5. Check valves aging assessment

    International Nuclear Information System (INIS)

    Haynes, H.D.

    1991-01-01

    In support of the NRC Nuclear Plant Aging Research (NPAR) program, the Oak Ridge National Laboratory (ORNL) has carried out an assessment of several check value diagnostic monitoring methods, in particular, those based on measurements of acoustic emission, ultrasonics, and magnetic flux. The evaluations have focussed on the capabilities of each method to provide information useful in determining check valve aging and service wear effects, check valve failures, and undesirable operating modes. This paper describes the benefits and limitations associated with each method and includes recent laboratory and field test data, including data obtained from the vendors who recently participated in a comprehensive series of tests directed by a nuclear industry users group. In addition, as part of the ORNL Advanced Diagnostic Engineering Research and Development Center (ADEC), two novel nonintrusive monitoring methods were developed that provide several unique capabilities. These methods, based on external ac- an dc-magnetic monitoring are also described. None of the examined methods could, by themselves, monitor both the instantaneous position and motion of check valve internals and valve leakage; however, the combination of acoustic emission monitoring with one of the other methods provides the means to determine vital check valve operational information

  6. Mitigating check valve slamming and subsequentwater hammer events for PPFS using MOC

    International Nuclear Information System (INIS)

    Tian Wenxi; Su Guanghui; Wang Gaopeng; Qiu Suizheng; Xiao Zejun

    2009-01-01

    The method of characteristic (MOC) was adopted to analyze the check valve-induced water hammer behaviors for a Parallel Pumps Feedwater System (PPFS) during the alternate startup process. The motion of check valve disc was simulated using inertial valve model. Transient parameters including the pressure oscillation, local flow velocity and slamming of the check valve disc etc. have been obtained. The results showed that severe slamming between the valve disc and valve seat occurred during the alternate startup of parallel pumps. The induced maximum pressure vibration amplitude is up to 5.0 MPa. The scheme of appending a damping torque to slow down the check valve closing speed was also performed to mitigate of water hammer. It has been numerically approved to be an effective approach. (authors)

  7. Mitigating check valve slamming and subsequentwater hammer events for PPFS using MOC

    Institute of Scientific and Technical Information of China (English)

    TIAN Wenxi; SU Guanghui; WANG Gaopeng; QIU Suizheng; XIAO Zejun

    2009-01-01

    The method of characteristic (MOC) was adopted to analyze the check valve-induced water hammer behaviors for a Parallel Pumps Feedwater System (PPFS) during the alternate startup process. The motion of check valve disc was simulated using inertial valve model. Transient parameters including the pressure oscillation, local flow velocity and slamming of the check valve disc etc. have been obtained. The results showed that severe slamming between the valve disc and valve seat occurred during the alternate startup of parallel pumps. The induced maximum pressure vibration amplitude is up to 5.0 MPa. The scheme of appending a damping torque to slow down the check valve closing speed was also performed to mitigate of water hammer. It has been numerically approved to be an effective approach.

  8. Oil Stiction in Fast Switching Annular Seat Valves for Digital Displacement Fluid Power Machines

    DEFF Research Database (Denmark)

    Roemer, Daniel Beck; Johansen, Per; Pedersen, Henrik C.

    2014-01-01

    Digital Displacement (DD) fluid power machines utilizes electronically controlled seat valves connected to pressure chambers to obtain variable displacement with high operational efficiency and high bandwidth. To achieve high efficiency, fast valve switching is essential and all aspects related...... to the dynamic behaviour of the seat valves must be considered to optimize the machine efficiency. A significant effect influencing the valves switching performance is the presence of oil stiction when separating the contact surfaces in valve opening movement. This oil stiction force is limited by cavitation...... for low pressure levels, e.g. valves connected to the low pressure manifold, however for valves operated at higher pressure levels, the oil stiction force is dominating when the separating surfaces are close to contact. This paper presents an analytic solution to the oil stiction force for annular seat...

  9. Aortic valve replacement and the stentless Freedom SOLO valve

    NARCIS (Netherlands)

    Wollersheim, L.W.L.M.

    2016-01-01

    Aortic valve stenosis has become the most prevalent valvular heart disease in Europe and North America, and is generally caused by age-related calcification of the aortic valve. For most patients, severe symptomatic aortic stenosis needs effective mechanical relief in the form of valve replacement

  10. Comparative study of Butterfly valves

    International Nuclear Information System (INIS)

    Galmes Belmonte, F.B.

    1998-01-01

    This work tries to justify the hydrodynamic butterfly valves performance, using the EPRI tests, results carried out in laboratory and in situ. This justification will be possible if: - The valves to study are similar - Their performance is calculated using EPRI's methodology Looking for this objective, the elements of the present work are: 1. Brief EPRI butterfly valve description it wild provide the factors which are necessary to define the butterfly valves similarity. 2. EPRI tests description and range of validation against test data definition. 3. Description of the spanish butterfly analyzed valves, and comparison with the EPRI performance results, to prove that this valves are similar to the EPRI test valves. In this way, it will not be necessary to carry out particular dynamic tests on the spanish valves to describe their hydrodynamic performance. (Author)

  11. A symmetric safety valve

    International Nuclear Information System (INIS)

    Burtraw, Dallas; Palmer, Karen; Kahn, Danny

    2010-01-01

    How to set policy in the presence of uncertainty has been central in debates over climate policy. Concern about costs has motivated the proposal for a cap-and-trade program for carbon dioxide, with a 'safety valve' that would mitigate against spikes in the cost of emission reductions by introducing additional emission allowances into the market when marginal costs rise above the specified allowance price level. We find two significant problems, both stemming from the asymmetry of an instrument that mitigates only against a price increase. One is that most important examples of price volatility in cap-and-trade programs have occurred not when prices spiked, but instead when allowance prices collapsed. Second, a single-sided safety valve may have unintended consequences for investment. We illustrate that a symmetric safety valve provides environmental and welfare improvements relative to the conventional one-sided approach.

  12. FEATURES OF CONTROLLING ELECTROPNEUMATIC VALVES OF ACTUATOR TO CONTROL ITS CLUTCH WITH ACCELERATION VALVE

    Directory of Open Access Journals (Sweden)

    O. A. Yaryta

    2018-01-01

    Full Text Available The article deals with one of the ways to control an actuator of the automated clutch control system. The aim is to design control of the electropneumatic actuator, to control its coupling with the acceleration valve on the basis of experimental research as well as to provide rational parameters of the automated clutch control system for the robotic transmission. The feature of the system is an acceleration valve in the design of the electropneumatic actuator to control the clutch. New links demand to adjust the way to control the actuator. The connection of Pulse-Width Modulation (PWM with single power supply pulses to control electropneumatic valves is substantiated. The quantitative characteristics of single control pulses and PWM ones are determined. The error of operation accuracy for various ways of the control of the electropneumatic actuator to control the clutch of the robotic transmission is determined. Obtained separate PWM area is designed to suppress the initial hysteresis when the rod of the clutch actuator is moved. An algorithm for the operation of a clutch control system is proposed, taking into account the use of two modes of operation of solenoid valves. A graphical interpretation of the clutch control algorithm is presented, which gives an idea of the location of the constant signal feeding zones to the solenoid valve, as well as the operation areas of the solenoid valve in PWM mode. The control algorithm of the clutch booster provides a mode of guaranteed absence of excess pressure in the pneumatic cylinder after releasing the clutch pedal, provided that two normally closed solenoid valves are used. This configuration of the electro-pneumatic clutch control system allows the use of an emergency clutch release system in case of voltage absence. The reference algorithm for filtering the array of data coming from the feedback sensor, as well as the numerical values of the delay caused by the presence of a filter, are given.

  13. Valve spindle gland

    International Nuclear Information System (INIS)

    Burda, Z.; Harazim, A.; Kerlin, K.

    1979-01-01

    A gland is proposed of the valve spindle designed for radioactive or otherwise harmful media, such as in nuclear power plant primary circuits. The gland is installed in the valve cover and consists of a primary and a secondary part and of a gland case partitioning the gland space into two chambers. The bottom face of the gland case is provided with a double-sided collar for controlling the elements of the bottom primary gland while the top face is provided with a removable flange. (M.S.)

  14. Building valve amplifiers

    CERN Document Server

    Jones, Morgan

    2013-01-01

    Building Valve Amplifiers is a unique hands-on guide for anyone working with tube audio equipment--as an electronics hobbyist, audiophile or audio engineer. This 2nd Edition builds on the success of the first with technology and technique revisions throughout and, significantly, a major new self-build project, worked through step-by-step, which puts into practice the principles and techniques introduced throughout the book. Particular attention has been paid to answering questions commonly asked by newcomers to the world of the valve, whether audio enthusiasts tackling their first build or

  15. Valve thrombosis following transcatheter aortic valve implantation: a systematic review.

    Science.gov (United States)

    Córdoba-Soriano, Juan G; Puri, Rishi; Amat-Santos, Ignacio; Ribeiro, Henrique B; Abdul-Jawad Altisent, Omar; del Trigo, María; Paradis, Jean-Michel; Dumont, Eric; Urena, Marina; Rodés-Cabau, Josep

    2015-03-01

    Despite the rapid global uptake of transcatheter aortic valve implantation, valve trombosis has yet to be systematically evaluated in this field. The aim of this study was to determine the clinical characteristics, diagnostic criteria, and treatment outcomes of patients diagnosed with valve thrombosis following transcatheter aortic valve implantation through a systematic review of published data. Literature published between 2002 and 2012 on valve thrombosis as a complication of transcatheter aortic valve implantation was identified through a systematic electronic search. A total of 11 publications were identified, describing 16 patients (mean age, 80 [5] years, 65% men). All but 1 patient (94%) received a balloon-expandable valve. All patients received dual antiplatelet therapy immediately following the procedure and continued to take either mono- or dual antiplatelet therapy at the time of valve thrombosis diagnosis. Valve thrombosis was diagnosed at a median of 6 months post-procedure, with progressive dyspnea being the most common symptom. A significant increase in transvalvular gradient (from 10 [4] to 40 [12] mmHg) was the most common echocardiographic feature, in addition to leaflet thickening. Thrombus was not directly visualized with echocardiography. Three patients underwent valve explantation, and the remaining received warfarin, which effectively restored the mean transvalvular gradient to baseline within 2 months. Systemic embolism was not a feature of valve thrombosis post-transcatheter aortic valve implantation. Although a rare, yet likely under-reported complication of post-transcatheter aortic valve implantation, progressive dyspnea coupled with an increasing transvalvular gradient on echocardiography within the months following the intervention likely signifies valve thrombosis. While direct thrombus visualization appears difficult, prompt initiation of oral anticoagulation therapy effectively restores baseline valve function. Copyright © 2014

  16. Valve Concepts for Microfluidic Cell Handling

    Directory of Open Access Journals (Sweden)

    M. Grabowski

    2010-01-01

    Full Text Available In this paper we present various pneumatically actuated microfluidic valves to enable user-defined fluid management within a microfluidic chip. To identify a feasible valve design, certain valve concepts are simulated in ANSYS to investigate the pressure dependent opening and closing characteristics of each design. The results are verified in a series of tests. Both the microfluidic layer and the pneumatic layer are realized by means of soft-lithographic techniques. In this way, a network of channels is fabricated in photoresist as a molding master. By casting these masters with PDMS (polydimethylsiloxane we get polymeric replicas containing the channel network. After a plasma-enhanced bonding process, the two layers are irreversibly bonded to each other. The bonding is tight for pressures up to 2 bar. The valves are integrated into a microfluidic cell handling system that is designed to manipulate cells in the presence of a liquid reagent (e.g. PEG – polyethylene glycol, for cell fusion. For this purpose a user-defined fluid management system is developed. The first test series with human cell lines show that the microfluidic chip is suitable for accumulating cells within a reaction chamber, where they can be flushed by a liquid medium.

  17. Low radiation dose non-contrast cardiac CT: is it of value in the evaluation of mechanical aortic valve

    International Nuclear Information System (INIS)

    Bazeed, Mohamed Fayez; Moselhy, Mohamed Saleh; Rezk, Ahmad Ibrahim; Al-Murayeh, Mushabab Ayedh

    2012-01-01

    Background: Prosthetic bileaflet mechanical valve function has been traditionally evaluated using echocardiography and fluoroscopy. Multidetector computed tomography (MDCT) is a novel technique for cardiac evaluation. Purpose: To evaluate bileaflet mechanical aortic valves using a low-milliampere (mA), non-contrast MDCT protocol with a limited scan range. Material and Methods: Forty patients with a bileaflet mechanical aortic valve were evaluated using a non-contrast, low-mA, ECG-gated 64 MDCT protocol with a limited scan range. MDCT findings of opening and closing valve angles were correlated to fluoroscopy and echocardiography. Also, the valve visibility was evaluated on MDCT and fluoroscopy according to a 3-point grading scale. Results: The visualization score with the MDCT was significantly superior to the fluoroscopy (3 vs. 2.7). A strong correlation was noted between the opening (r = 0.82) and closing (r = 0.96) valve angles with MDCT and fluoroscopy without a statistically significant difference (P = 0.31 and 0.16, respectively). The mean effective radiation dose of the suggested protocol was 4 ± 0.5 mSv. Five valves were evaluated using transesophageal echocardiography because the valves were difficult to evaluate with transthoracic echocardiography, and all of these valves were evaluated optimally with MDCT. A high-pressure gradient was noted in nine valves, and the MDCT showed that seven of these valves inadequately opened, and two valves opened well, which resulted in patient valve mismatch. Incomplete valve closure was noted in five valves, and the echocardiography showed significant transvalvular regurgitation in all five valves. Conclusion: MDCT can provide a precise measurement of valve function and can potentially evaluate high-pressure gradients and transvalvular regurgitation

  18. Low radiation dose non-contrast cardiac CT: is it of value in the evaluation of mechanical aortic valve

    Energy Technology Data Exchange (ETDEWEB)

    Bazeed, Mohamed Fayez (Dept. of Diagnostic Radiology, Faculty of Medicine, Mansoura Univ. (Egypt)), email: m_bazeed@yahoo.com; Moselhy, Mohamed Saleh (Cardiology Dept. Faculty of Medicine, Suez Canal Univ. (Egypt)); Rezk, Ahmad Ibrahim (Dept. of Cardiac Surgery, Faculty of Medicine, Aim Shams Univ. (Egypt)); Al-Murayeh, Mushabab Ayedh (Dept. of Cardiac Services, Armed Forces Hospitals Southern Region (Saudi Arabia))

    2012-05-15

    Background: Prosthetic bileaflet mechanical valve function has been traditionally evaluated using echocardiography and fluoroscopy. Multidetector computed tomography (MDCT) is a novel technique for cardiac evaluation. Purpose: To evaluate bileaflet mechanical aortic valves using a low-milliampere (mA), non-contrast MDCT protocol with a limited scan range. Material and Methods: Forty patients with a bileaflet mechanical aortic valve were evaluated using a non-contrast, low-mA, ECG-gated 64 MDCT protocol with a limited scan range. MDCT findings of opening and closing valve angles were correlated to fluoroscopy and echocardiography. Also, the valve visibility was evaluated on MDCT and fluoroscopy according to a 3-point grading scale. Results: The visualization score with the MDCT was significantly superior to the fluoroscopy (3 vs. 2.7). A strong correlation was noted between the opening (r = 0.82) and closing (r = 0.96) valve angles with MDCT and fluoroscopy without a statistically significant difference (P = 0.31 and 0.16, respectively). The mean effective radiation dose of the suggested protocol was 4 +- 0.5 mSv. Five valves were evaluated using transesophageal echocardiography because the valves were difficult to evaluate with transthoracic echocardiography, and all of these valves were evaluated optimally with MDCT. A high-pressure gradient was noted in nine valves, and the MDCT showed that seven of these valves inadequately opened, and two valves opened well, which resulted in patient valve mismatch. Incomplete valve closure was noted in five valves, and the echocardiography showed significant transvalvular regurgitation in all five valves. Conclusion: MDCT can provide a precise measurement of valve function and can potentially evaluate high-pressure gradients and transvalvular regurgitation

  19. Cavitation problems in sodium valves

    International Nuclear Information System (INIS)

    Elie, X.

    1976-01-01

    Cavitation poses few problems for sodium valves, in spite of the fact that the loops are not pressurized. This is no doubt due to the low flow velocities in the pipes. For auxiliary loop valves we are attempting to standardize performances with respect to cavitation. For economic reasons cavitation thresholds are approached with large diameter valves. (author)

  20. Post-traumatic tricuspid valve insufficiency. 2 cases of delayed clinical manifestation.

    OpenAIRE

    Bortolotti, U; Scioti, G; Milano, A; Guglielmi, C; Benedetti, M; Tartarini, G; Balbarini, A

    1997-01-01

    We present 2 cases of tricuspid insufficiency following blunt chest trauma: 1 was diagnosed 5 months after the trauma and the other, 20 years after the trauma. In both patients, the tricuspid valve was replaced with a porcine bioprosthesis, because valve repair was not considered feasible. These cases emphasize the variability of clinical presentation of post-traumatic tricuspid valve insufficiency and indicate the need for close follow-up of patients after major thoracic trauma.

  1. Fast-Valving of Large Steam Turbine Units as a Means of Power System Security Enhancement

    OpenAIRE

    Bogdan Sobczak; Robert Rink; Rafał Kuczyński; Robert Trębski

    2014-01-01

    Fast-valving assists in maintaining system stability following a severe transmission system fault by reducing the turbine mechanical power. Fast-valving consists in rapid closing and opening of steam valves in an adequate manner to reduce the generator accelerating power following the recognition of a severe fault. FV can be an effective and economical method of meeting the performance requirements of a power system in the presence of an increase in wind and solar generation in the power syst...

  2. Validation of Model-Based Prognostics for Pneumatic Valves in a Demonstration Testbed

    Science.gov (United States)

    2014-10-02

    predict end of life ( EOL ) and remaining useful life (RUL). The approach still follows the general estimation-prediction framework devel- oped in the...atmosphere, with linearly increasing leak area. kA2leak = Cleak (16) We define valve end of life ( EOL ) through open/close time limits of the valves, as in...represents end of life ( EOL ), and ∆kE represents remaining useful life (RUL). For valves, timing requirements are provided that de- fine the maximum

  3. Radiographic investigation of the function of the Bjoerk-Shiley artificial valve

    Energy Technology Data Exchange (ETDEWEB)

    Erdelyi, M Jr [Orszagos Roentgen es Sugarfizikai Intezet, Budapest (Hungary)

    1980-01-01

    The normal opening and closing mechanism of the tip-up valve, containing a metal ring, was investigated by kino and spot-film techniques in 58 patients. A new and simple method was elaborated for the calculation of the opening angle of the tip-up valve, rendering superfluous the complicated calculations published by Bjoerk. In accordance with literature data the regular opening angle of the examined 71 valve prostheses was found to be 60 deg (+-2 deg).

  4. NRC test results and operations experience provide insights for a new gate valve stem force correlation

    International Nuclear Information System (INIS)

    Watkins, John C.; Steele, Robert Jr.; DeWall, Kevin G.; Weidenhamer, G.H.; Rothberg, O.O.

    1994-01-01

    This paper presents the results of testing sponsored by the NRC to assess valve and motor operator performance under varying pressure and fluid conditions. This effort included an examination of the methods used by the industry to predict the required stem force of a valve, and research to provide guidelines for the extrapolation of in situ test results to design basis conditions.Years ago, when most of these valves were originally installed, the industry used a set of equations to determine analytically that the valves' motor-operators were large enough and the control switches were set high enough to close the valves at their design basis conditions. Our research has identified several inconsistencies with the industry's existing gate valve stem force equation and has challenged the overly simplistic assumptions inherent in its use. This paper discusses the development of the INEL correlation, which serves as the basis for a method to bound the stem force necessary to close flexwedge gate valves whose operational characteristics have been shown to be predictable. As utilities undertake to provide assurance of their valves' operability, this ability to predict analytically the required stem force is especially important for valves that cannot be tested at design basis conditions. For such valves, the results of tests conducted at less severe conditions can be used with the INEL correlation to make the necessary prediction. ((orig.))

  5. Ecological aspects of the radiation-migration equivalence principle in a closed fuel cycle and its comparative assessment with the ALARA principle

    International Nuclear Information System (INIS)

    Poluektov, P.P.; Lopatkin, A.V.; Nikipelov, B.V.; Rachkov, V.I.; Sukhanov, L.P.; Voloshin, S.V.

    2005-01-01

    The errors and uncertainties arising in the determination of radionuclide escape from the RW burial require the use of extremely conservative estimates. In the limit, the nuclide concentrations in the waste may be used as estimates of their concentrations in underground waters. On this basis, it is possible to evaluate the corresponding radio-toxicities (by normalizing to the interference levels) of individual components and radioactive waste as a whole or the effective radio-toxicities (by dividing the radionuclide radio-toxicities into the retardation factors for the nuclide transfer with underground waters). This completely coincides with the procedure of performing the limiting conservative estimate according to the traditional approach with the use of scenarios, escape models, and the corresponding codes. A comparison of radio-toxicities for waste with those for natural uranium consumed for producing a required fuel results in the notion of radiation-migration equivalence for individual waste components and radioactive waste as a whole. Therefore, the radiation-migration equivalence corresponds to the limiting conservative estimate in the traditional approach to the determination of RW disposal safety in comparison with the radiotoxicity of natural uranium. The amounts of radionuclides in fragments (and actinides) and the corresponding weight of heavy metal in the fuel are compared with due regard for the hazard (according to the NRB-99 standards), the nuclide mobility (through the sorption retardation factors), the retention of radioactive waste by the solid matrix, and the contribution from the chains of uranium fission products. It was noted above that the RME principle is aimed at ensuring the radiological safety of the present and future generations and the environment through the minimization of radioactive waste upon reprocessing. This is attended by reaching a reasonably achievable, low level of radiological action in the context of modern science, i

  6. Transcatheter aortic valve implantation in failed bioprosthetic surgical valves

    DEFF Research Database (Denmark)

    Dvir, Danny; Webb, John G; Bleiziffer, Sabine

    2014-01-01

    for patients with structural valve deterioration; however, a comprehensive evaluation of survival after the procedure has not yet been performed. OBJECTIVE: To determine the survival of patients after transcatheter valve-in-valve implantation inside failed surgical bioprosthetic valves. DESIGN, SETTING......, stroke, and New York Heart Association functional class. RESULTS: Modes of bioprosthesis failure were stenosis (n = 181 [39.4%]), regurgitation (n = 139 [30.3%]), and combined (n = 139 [30.3%]). The stenosis group had a higher percentage of small valves (37% vs 20.9% and 26.6% in the regurgitation...... and combined groups, respectively; P = .005). Within 1 month following valve-in-valve implantation, 35 (7.6%) patients died, 8 (1.7%) had major stroke, and 313 (92.6%) of surviving patients had good functional status (New York Heart Association class I/II). The overall 1-year Kaplan-Meier survival rate was 83...

  7. Seismic qualification of motor operated valves - alternate approach

    International Nuclear Information System (INIS)

    Bruck, P.M.; Eissa, M.A.

    1998-01-01

    This paper presents a potential alternate method for determining operating capacity of motor-operated valves subjected to seismic and other applicable loadings. As a result of programs at nuclear facilities to ensure the operational capability of MOVs (under NRC GL89-10), extensive analytical focus to develop the structural capability of valves has ensued. In the past, seismic qualification of valves typically addressed the strength of the topwork structure to resist inertial loading from excitation of the large valve actuator mass. These evaluations paid little or no consideration to the loading resulting from valve closing forces. The focus of the recent efforts is to develop the maximum operational capability of the valve, in terms of thrust, with consideration of seismic and other services loading as applicable. The alternate method outlined in this paper presents a series of thrust capacity curves, with reduction factors for seismic loading which can be applied and developed to determine safe thrust loadings without performing extensive analytical effort. A similar approach was put forward by the SQUG GIP approach to MOVs to ensure the safe operation of valves based on past earthquake experience. However, the GIP approach cannot be used to determine safe operational loads and thus has limited use in the necessary analysis required for GL89-10 programs at nuclear facilities. (orig.)

  8. Aortic valve sparing root surgery for Marfan syndrome.

    Science.gov (United States)

    Matalanis, George; Perera, Nisal K

    2017-11-01

    Aortic valve sparing root surgery (AVSRS) is a safe and durable alternative for patients with dilated roots or pure aortic regurgitation (AR), which avoids the risks of anticoagulation or valvular degeneration with prosthetic valves. Notwithstanding the theoretical challenges of greater tissue fragility in Marfan syndrome (MFS), AVSRS has been demonstrated to have equal outcomes in this condition as it does in those without MFS. The benefits of retaining the native aortic valve in this generally younger age group extend beyond those of avoiding the inconvenience and complications of prolonged exposure to anticoagulants and include ease of management for future aortic, cardiac and non-cardiac procedures which are the norm for these patients. The essential principles of AVSRS in MFS do not differ from those for the rest of the population. Successful repair and durable valve function depend on a sound understanding of the close interaction between the structure and function of this exquisitely designed piece of engineering. We are fortunate to have numerous tools in our surgical armamentarium to preserve these valves. It is the purpose of this paper to demystify the complex structure-function interactions of the aortic valve, thereby gaining an intuition for AVSRS. We will also elaborate on specific technical details of established techniques that we have found successful in preserving the normal function of these valves in the long term.

  9. BIF butterfly valve life extension at WNP-2

    International Nuclear Information System (INIS)

    Armstrong, D.

    1991-01-01

    Primary containment purging, venting, inerting, and reactor building ventilation at the WNP-2 plant are accomplished with a series of large butterfly valves. A total of 31 valves which are similar in design, but of different sizes, employ an elastomer to achieve sealing integrity when closed. These valves, which were originally manufactured by BIF, a unit of General Signal, range in size from 18 to 84 inches in diameter. Service life in the plant was much less than desired for safety-related equipment, and several seal failures had been experienced shortly after valve overhaul. This program covers a design change made to enhance performance of the elastomer seal to achieve a very meaningful life extension. While numerous configurations of BIF valves exist, this work relates only to the model 657 unit assembled with an elastomer seal mounted onto the valve disc by a stainless steel clamping ring held with studs and nuts. The problems encountered, and the steps taken to resolve the deficiencies may, however, be applicable to other butterfly valve configurations

  10. Piezoelectric valve for massive gas injection in ASDEX upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Dibon, Mathias; Neu, Rudolf [Max-Planck-Institute for Plasmaphysics, Boltzmannstr. 2, 85748 Garching (Germany); Technical University Munich, Boltzmannstr. 15, 85748 Garching (Germany); Herrmann, Albrecht; Mank, Klaus; Mertens, Vitus; Pautasso, Gabriella; Ploeckl, Bernhard [Max-Planck-Institute for Plasmaphysics, Boltzmannstr. 2, 85748 Garching (Germany)

    2016-07-01

    A sudden loss of plasma temperature can cause a disruption, which poses a significant problem for current Tokamaks and future fusion devices. Hence, mitigating forces and thermal loads during disruptions is important for the integrity of the vessel and first wall components. Therefore, high speed gas valves are used to deliver a pulse of noble gas onto the plasma, which irradiates the thermal energy quickly, avoiding localized heat loads and mechanical stress due to induced currents. A new design for such a valve is currently under development. The valve plate is driven by two piezoelectric stack actuators. The stroke of the actuators (0.07 mm) is amplified by a monolithic titanium frame and reaches 2 mm. The frame also serves as spring to pre-load the actuators. In the idle state, it also presses the conical valve plate into the seal, closing the gas chamber (42 cm{sup 3}). The actuators accelerate the stem and the valve plate until it is fully opened after 2 ms. The orifice of the valve has a diameter of 14 mm. This allows a peak mass flow rate of the gas up to 8 . 10{sup 4} (Pa.m)/(s) after 1.8 ms and an average mass flow rate of 2 . 10{sup 4} (Pa.m)/(s) over the evacuation time of 10 ms. Therefore, one valve would be sufficient to deliver the required amount of gas to mitigate disruptions at ASDEX Upgrade.

  11. Water supply method to the fuel cell cooling water system; Nenryo denchi reikyakusuikei eno kyusui hoho

    Energy Technology Data Exchange (ETDEWEB)

    Urata, T. [Tokyo (Japan); Nishida, S. [Tokyo (Japan)

    1996-12-17

    The conventional fuel cell has long cooling water piping ranging from the fuel cell exit to the steam separator; in addition, the supply water is cooler than the cooling water. When the amount of supply water increases, the temperature of the cooling water is lowered, and the pressure fluctuation in the steam separator becomes larger. This invention relates to the water supply method of opening the supply water valve and supplying water from the supply water system to the cooling water system in accordance with the signal of the level sensor of the steam separator, wherein opening and closing of the supply valve are repeated during water supply. According to the method the pressure drop in every water supply becomes negligibly small; therefore, the pressure fluctuation of the cooling water system can be made small. The interval of the supply water valve from opening to closing is preferably from 3 seconds to 2 minutes. The method is effective when equipment for recovering heat from the cooling water is installed in the downstream pipeline of the fuel cell. 2 figs.

  12. SAFETY SHUTOFF VALVE

    DEFF Research Database (Denmark)

    2010-01-01

    It is disclosed a shut-off valve which acts automatically and has a fully mechanical performance with respect to the loosing of the tower-shape part balance under the effect of the special acceleration Which is arisen from the quakes waves or serious vibrations, while such vibrations are mainly r...

  13. Heart valve surgery - discharge

    Science.gov (United States)

    ... ACC guideline for the management of patients with valvular heart disease: executive summary: a report of the American College ... Editorial team. Related MedlinePlus Health Topics Heart Surgery Heart Valve Diseases Browse the Encyclopedia A.D.A.M., Inc. ...

  14. Poppet valve tester

    Science.gov (United States)

    Tellier, G. F.

    1973-01-01

    Tester investigates fundamental factors affecting cyclic life and sealing performance of valve seats and poppets. Tester provides for varying impact loading of poppet against seat and rate of cycling, and controls amount and type of relative motion between sealing faces of seat and poppet. Relative motion between seat and poppet can be varied in three modes.

  15. Thermostatic Radiator Valve Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Dentz, Jordan [Advanced Residential Integrated Energy Solutions Collaborative, New York, NY (United States); Ansanelli, Eric [Advanced Residential Integrated Energy Solutions Collaborative, New York, NY (United States)

    2015-01-01

    A large stock of multifamily buildings in the Northeast and Midwest are heated by steam distribution systems. Losses from these systems are typically high and a significant number of apartments are overheated much of the time. Thermostatically controlled radiator valves (TRVs) are one potential strategy to combat this problem, but have not been widely accepted by the residential retrofit market.

  16. Blocked Urethral Valves

    Science.gov (United States)

    ... if any damage has occurred to the upper urinary tract. Your pediatrician will consult with a pediatric nephrologist (kidney specialist) or nurologist, who may recommend surgery to remove the obstructing valves and prevent further infection or damage to the kidneys or urinary system. ...

  17. Numerical Analysis of Combined Valve Hydrodynamic Characteristics for Turbine System

    Energy Technology Data Exchange (ETDEWEB)

    Bhowmik, P. K.; Shamim, J. A.; Gairola, A.; Arif, M.; Suh, Kune Y. [Seoul National Univ., Seoul (Korea, Republic of)

    2014-05-15

    Flow characteristic curves are plotted by calculating the ratio of the measured mass flow rate versus the theoretical mass flow rate. The flow characteristic curves are utilized to accurately test the performance of the control valve of turbine system to ensure the highest controllability and reliability of the power conversion system of large and small power plants. Turbine converts the kinetic energy of steam to mechanical energy of rotor blades in power conversion system. The electrical energy output from the generator of which the rotor is coupled with that of the turbine depends on the rotation velocity of the turbine bucket. The rotation velocity is proportional to the mass flow rate (steam or gas) to the turbine through valves and nozzles. The turbine comprises fast acting governing control valves and stop valves acting against the seat in the flow passage in the closed position. The turbine control valve regulates the mass flow rate entering the first nozzle of a turbine. The main function of stop valve is to close the fluid inlet rapidly in response to a fast close signal to swiftly cut off the flow through the valve inlet. Both these valves contribute attractively to improvement of the power system transient stability as well. To improve the efficiency of power conversion system many investigation have been done by researcher by focusing on the cycle layout or working fluid or by improving the flow path of the working fluid. The main focus is to find out the best option for combined cycle power plant by analyzing four different cycle configuration. Next research phase focused on different way to enhance the cycle efficiency. As the electrical power output from the generator is proportional to the mass flow rate to the turbine through the valve, it should preferably operate linearly. In reality, however, the valve has the various flow characteristics pursuant to the stem lift. Thus, the flow characteristic and control performance are needed to be designed

  18. Numerical Analysis of Combined Valve Hydrodynamic Characteristics for Turbine System

    International Nuclear Information System (INIS)

    Bhowmik, P. K.; Shamim, J. A.; Gairola, A.; Arif, M.; Suh, Kune Y.

    2014-01-01

    Flow characteristic curves are plotted by calculating the ratio of the measured mass flow rate versus the theoretical mass flow rate. The flow characteristic curves are utilized to accurately test the performance of the control valve of turbine system to ensure the highest controllability and reliability of the power conversion system of large and small power plants. Turbine converts the kinetic energy of steam to mechanical energy of rotor blades in power conversion system. The electrical energy output from the generator of which the rotor is coupled with that of the turbine depends on the rotation velocity of the turbine bucket. The rotation velocity is proportional to the mass flow rate (steam or gas) to the turbine through valves and nozzles. The turbine comprises fast acting governing control valves and stop valves acting against the seat in the flow passage in the closed position. The turbine control valve regulates the mass flow rate entering the first nozzle of a turbine. The main function of stop valve is to close the fluid inlet rapidly in response to a fast close signal to swiftly cut off the flow through the valve inlet. Both these valves contribute attractively to improvement of the power system transient stability as well. To improve the efficiency of power conversion system many investigation have been done by researcher by focusing on the cycle layout or working fluid or by improving the flow path of the working fluid. The main focus is to find out the best option for combined cycle power plant by analyzing four different cycle configuration. Next research phase focused on different way to enhance the cycle efficiency. As the electrical power output from the generator is proportional to the mass flow rate to the turbine through the valve, it should preferably operate linearly. In reality, however, the valve has the various flow characteristics pursuant to the stem lift. Thus, the flow characteristic and control performance are needed to be designed

  19. Tricuspid valve endocarditis

    Science.gov (United States)

    Hussain, Syed T.; Witten, James; Shrestha, Nabin K.; Blackstone, Eugene H.

    2017-01-01

    Right-sided infective endocarditis (RSIE) is less common than left-sided infective endocarditis (IE), encompassing only 5–10% of cases of IE. Ninety percent of RSIE involves the tricuspid valve (TV). Given the relatively small numbers of TVIE cases operated on at most institutions, the purpose of this review is to highlight and discuss the current understanding of IE involving the TV. RSIE and TVIE are strongly associated with intravenous drug use (IVDU), although pacemaker leads, defibrillator leads and vascular access for dialysis are also major risk factors. Staphylococcus aureus is the predominant causative organism in TVIE. Most patients with TVIE are successfully treated with antibiotics, however, 5–16% of RSIE cases eventually require surgical intervention. Indications and timing for surgery are less clear than for left-sided IE; surgery is primarily considered for failed medical therapy, large vegetations and septic pulmonary embolism, and less often for TV regurgitation and heart failure. Most patients with an infected prosthetic TV will require surgery. Concomitant left-sided IE has its own surgical indications. Earlier surgical intervention may potentially prevent further destruction of leaflet tissue and increase the likelihood of TV repair. Fortunately, TV debridement and repair can be accomplished in most cases, even those with extensive valve destruction, using a variety of techniques. Valve repair is advocated over replacement, particularly in IVDUs patients who are young, non-compliant and have a higher risk of recurrent infection and reoperation with valve replacement. Excising the valve without replacing, it is not advocated; it has been reported previously, but these patients are likely to be symptomatic, particularly in cases with septic pulmonary embolism and increased pulmonary vascular resistance. Patients with concomitant left-sided involvement have worse prognosis than those with RSIE alone, due predominantly to greater likelihood of

  20. Timing tests: automatic valve closure for tritium leaks

    International Nuclear Information System (INIS)

    Hanel, S.

    1976-01-01

    How fast can an automotive valve be closed after a tritium leak occurs in a system. Tests described found that a valve can be closed within fifteen seconds of leakage. In one practical example considered, this delay would limit loss of tritium from a plumbing leak in a tritium system to 1 1 / 4 g. The tests were made in a typical LLL air-flush hood in which a tritium handling system had been installed. Incidental observations suggest that further study be made of a possible leak-actuated recovery system for an entire tritium facility

  1. Detection circuit of solenoid valve operation and control rod drive mechanism utilizing the circuit

    International Nuclear Information System (INIS)

    Ono, Takehiko.

    1976-01-01

    Object: To detect the operation of a plunger and detect opening and closing operations of a solenoid valve driving device due to change in impedance of a coil for driving the solenoid valve to judge normality and abnormality of the solenoid valve, thereby increasing reliance and safety of drive and control apparatus of control rods. Structure: An arrangement comprises a drive and operation detector section wherein the operation of a solenoid driving device for controlling power supply to a coil for driving the solenoid valve to control opening and closing of the solenoid valve, and a plunger operation detector section for detecting change in impedance of the drive coil to detect that the plunger of the solenoid valve is either in the opening direction or closing direction, whereby a predetermined low voltage such as not to activate the solenoid valve even when the solenoid valve is open or closed is applied to detect a current flowing into the coil at that time, thus detecting an operating state of the plunger. (Yoshino, Y.)

  2. Ethylene controlled ventilation. Energy conservation in the project 'Klep Dicht' (Close the Valve) and results of supplementary research; Ethyleengestuurde ventilatie. Energiebesparing in het project 'Klep Dicht' en resultaten van aanvullend onderzoek

    Energy Technology Data Exchange (ETDEWEB)

    Wildschut, J. [Praktijkonderzoek Plant en Omgeving PPO, Bloembollen, Boomkwekerij en Fruit, Lisse (Netherlands); Langner-Noort, L. [DLV Plant, Wageningen (Netherlands)

    2007-11-15

    The project ‘Close the Valve’ has been initiated with the aim of demonstrating the energy conservation options through ethylene-controlled ventilation of tulip flower bulb. During previous meetings on the ethylene analyzer, there were some urgent questions about practical use: What happens with the ethylene content during an Actellic treatment?; What is the influence of the ethylene content in outdoor air?; How is the ethylene distribution in the storage room?; The supplementary research involved the effect of ethylene in outdoor air, the distribution of ethylene in the cold store, and the behavior of ethylene during the period of the Actellic treatment (Actellic is an insecticide) [Dutch] Het project 'Klep Dicht' is opgezet met als doel de energiebesparingsmogelijkheden door ethyleengestuurde ventilatie van tulpenbollen te demonstreren. Tijdens eerdere bijeenkomsten over de ethyleenanalyser, kwamen een aantal dringende vragen uit de praktijk naar voren: Wat gebeurt er met het ethyleengehalte tijdens een Actellic-behandeling?; Hoe zit het met de invloed van het ethyleengehalte in de buitenlucht?; Hoe zit het met de ethyleenverdeling in de bewaarruimte? Het aanvullende onderzoek betrof het effect van ethyleen in de buitenlucht, de verdeling van het ethyleen in de bewaarcel, en het gedrag van ethyleen tijdens de periode van de actellicbehandeling (actellic is een insecticide)

  3. Investigation of a rotary valving system with variable valve timing for internal combustion engines

    Science.gov (United States)

    Cross, Paul C.; Hansen, Craig N.

    1994-11-01

    The objective of the program was to provide a functional demonstration of the Hansen Rotary Valving System with Variable Valve Timing (HRVS/VVT), capable of throttleless inlet charge control, as an alternative to conventional poppet-valves for use in spark ignited internal combustion engines. The goal of this new technology is to secure benefits in fuel economy, broadened torque band, vibration reduction, and overhaul accessibility. Additionally, use of the variable valve timing capability to vary the effective compression ratio is expected to improve multifuel tolerance and efficiency. Efforts directed at the design of HRVS components proved to be far more extensive than had been anticipated, ultimately requiring that proof-trial design/development work be performed. Although both time and funds were exhausted before optical or ion-probe types of in-cylinder investigation could be undertaken, a great deal of laboratory data was acquired during the course of the design/development work. This laboratory data is the basis for the information presented in this final report.

  4. Curved butterfly bileaflet prosthetic cardiac valve

    Science.gov (United States)

    McQueen, David M.; Peskin, Charles S.

    1991-06-25

    An annular valve body having a central passageway for the flow of blood therethrough with two curved leaflets each of which is pivotally supported on an accentric positioned axis in the central passageway for moving between a closed position and an open position. The leaflets are curved in a plane normal to the eccentric axis and positioned with the convex side of the leaflets facing each other when the leaflets are in the open position. Various parameters such as the curvature of the leaflets, the location of the eccentric axis, and the maximum opening angle of the leaflets are optimized according to the following performance criteria: maximize the minimum peak velocity through the valve, maximize the net stroke volume, and minimize the mean forward pressure difference, thereby reducing thrombosis and improving the hemodynamic performance.

  5. Fuel economy and torque tracking in camless engines through optimization of neural networks

    International Nuclear Information System (INIS)

    Ashhab, Moh'd Sami S.

    2008-01-01

    The feed forward controller of a camless internal combustion engine is modeled by inverting a multi-input multi-output feed forward artificial neural network (ANN) model of the engine. The engine outputs, pumping loss and cylinder air charge, are related to the inputs, intake valve lift and closing timing, by the artificial neural network model, which is trained with historical input-output data. The controller selects the intake valve lift and closing timing that will mimimize the pumping loss and achieve engine torque tracking. Lower pumping loss means better fuel economy, whereas engine torque tracking gurantees the driver's torque demand. The inversion of the ANN is performed with the complex method constrained optimization. How the camless engine inverse controller can be augmented with adaptive techniques to maintain accuracy even when the engine parts degrade is discussed. The simulation results demonstrate the effectiveness of the developed camless engine controller

  6. An air-pressure-free elastomeric valve for integrated nucleic acid analysis by capillary electrophoresis

    International Nuclear Information System (INIS)

    Jung, Wooseok; Barrett, Matthew; Brooks, Carla; Zenhausern, Frederic; Rivera, Andrew; Birdsell, Dawn N; Wagner, David M

    2015-01-01

    We present a new elastomeric valve for integrated nucleic acid analysis by capillary electrophoresis. The valve functions include metering to capture a designated volume of biological sample into a polymerase chain reaction (PCR) chamber, sealing to preserve the sample during PCR cycling, and transfer of the PCR-products and on-chip formamide post-processing for the analysis of DNA fragments by capillary gel electrophoresis. This new valve differs from prior art polydimethylsiloxane (PDMS) valves in that the valve is not actuated externally by air-pressure or vacuum so that it simplifies a DNA analysis system by eliminating the need for an air-pressure or vacuum source, and off-cartridge solenoid valves, control circuit boards and software. Instead, the new valve is actuated by a thermal cycling peltier assembly integrated within the hardware instrument that tightly comes in contact with a microfluidic cartridge for thermal activation during PCR, so that it spontaneously closes the valve without an additional actuator system. The valve has bumps in the designated locations so that it has a self-alignment that does not require precise alignment of a valve actuator. Moreover, the thickness of the new valve is around 600 μm with an additional bump height of 400 μm so that it is easy to handle and very feasible to fabricate by injection molding compared to other PDMS valves whose thicknesses are around 30–100 μm. The new valve provided over 95% of metering performance in filling the fixed volume of the PCR chamber, preserved over 97% of the sample volume during PCR, and showed very comparable capillary electrophoresis peak heights to the benchtop assay tube controls with very consistent transfer volume of the PCR-product and on-chip formamide. The new valve can perform a core function for integrated nucleic acid analysis by capillary electrophoresis. (paper)

  7. The progressive achievement of a closed fuel cycle in France; La mise en oeuvre progressive d'un cycle ferme en France

    Energy Technology Data Exchange (ETDEWEB)

    Hugelmann, D.; Devezeaux de Lavergne, J.G. [AREVA NC, 78 - Velizy Villacoublay (France)

    2008-03-15

    The author reviews the progressive building of a strong nuclear fuel cycle industry in France. The first major step was the abandon of the graphite-gas reactor system to the PWR system. The government's decision to opt for reactors operating with enriched uranium opened the way to the application at an industrial scale of uranium enrichment technology that was only confined to military purposes. The legal entity 'EURODIF S A' was founded at that time and the different production units of the George-Besse-1 enrichment plant entered into service progressively from 1978 to 1982. The Comurhex company was created in 1969, and was in charge of producing the uranium hexafluoride necessary to the fabrication of nuclear fuels. La-Hague plant entered into service in 1966, its aim was to process spent fuels from graphite-gas reactors. Inside this plant the HAO (High Activity Oxide) dedicated to PWR spent fuels was operating in 1974. The MELOX plant dedicated to the fabrication of mixed oxides fuels (Mox) entered into operation in 1995 (till now more than 5000 Mox assemblies have been fabricated. Another important step was the processing of Mox fuels. During these 30 years, the nuclear industry has made impressing progress concerning: the increase of burn-up rates, the performance of fuels, the increase in the volume being processed, the packaging of radioactive wastes, the development of nuclear transport, and a reduction of the impact on the environment. In order to maintain its level of performance the nuclear industry has made important investments concerning: mining (a global investment of 2.3*10{sup 9} euros), Comurhex-2 (a 610*10{sup 6} euros investment) and Georges-Besse-2 plant (a 3*10{sup 9} euros investment for the enrichment of uranium through centrifugation). (A.C.)

  8. Prediction of a required dynamic torque for motor-operated butterfly valves

    International Nuclear Information System (INIS)

    Bae, J. H.; Lee, K. N.; Jeong, W. K.

    2002-01-01

    This study describes the methodology for predicting a required dynamic torque in motor-operated butterfly valves. The results of this methodology have been compared with test data for motor-operated butterfly valves in nuclear power plant. With the close review of test data and torque prediction, it is concluded that the prediction methodology is conservative to predict a required dynamic torque of motor-operated butterfly valves. In addition, the information of correct differential pressure is vital to predict a required dynamic torque of motor-operated butterfly valves

  9. Cyclonic valve test: preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Monteiro, Andre Sampaio; Moraes, Carlos Alberto C.; Marins, Luiz Philipe M.; Soares, Fabricio; Oliveira, Dennis; Lima, Fabio Soares de; Airao, Vinicius [Petroleo Brasileiro S.A. (PETROBRAS), Rio de Janeiro, RJ (Brazil); Ton, Tijmen [Twister BV, Rijswijk (Netherlands)

    2012-07-01

    For many years, the petroleum industry has been developing a valve that input less shear to the flow for a given required pressure drop and this can be done using the cyclonic concept. This paper presents a comparison between the performances of a cyclonic valve (low shear) and a conventional globe valve. The aim of this work is to show the advantages of using a cyclonic low shear valve instead of the commonly used in the primary separation process by PETROBRAS. Tests were performed at PETROBRAS Experimental Center (NUEX) in Aracaju/SE varying some parameters: water cut; pressure loss (from 4 kgf/cm2 to 10 kgf/cm2); flow rates (30 m3/h and 45 m3/h). Results indicates a better performance of the cyclonic valve, if compared with a conventional one, and also that the difference of the performance, is a function of several parameters (emulsion stability, water content free, and oil properties). The cyclonic valve tested can be applied as a choke valve, as a valve between separation stages (for pressure drop), or for controlling the level of vessels. We must emphasize the importance to avoid the high shear imposed by conventional valves, because once the emulsion is created, it becomes more difficult to break it. New tests are being planned to occur in 2012, but PETROBRAS is also analyzing real cases where the applications could increase the primary process efficiency. In the same way, the future installations are also being designed considering the cyclonic valve usage. (author)

  10. Application of the gravimetric method to closing the material balance around the chop-leach cell of a spent-fuel reprocessing plant

    International Nuclear Information System (INIS)

    Fishbone, L.G.

    1985-01-01

    For a spent-fuel reprocessing plant handling commercial light-water-reactor fuel, plutonium accounting is traditionally done for the material balance area (MBA) extending from the input accountability tank to the product accountability tank - the process MBA. Consider an MBA comprising the chop-leach cell, with an inward flow consisting of the intact spent-fuel assemblies and outward flows consisting of leached hulls and dissolver solution. Given knowledge of the original uranium mass in the fuel and a measurement of the uranium-plutonium concentration ratio in the dissolver solution, the gravimetric method can be used to determine the amount of plutonium in the spent-fuel assemblies. A measurement of residual plutonium in the leached hulls would then permit the determination of a plutonium material balance for the chop-leach cell alone, since the volumetrically determined plutonium in the input accountability tank yields the plutonium in the flow leaving the chop-leach cell for the process MBA. The uncertainty in the balance can be estimated given the individual measurement uncertainties

  11. Multiple Irradiation Capsule Experiment (MICE)-3B Irradiation Test of Space Fuel Specimens in the Advanced Test Reactor (ATR) - Close Out Documentation for Naval Reactors (NR) Information

    Energy Technology Data Exchange (ETDEWEB)

    M. Chen; CM Regan; D. Noe

    2006-01-09

    Few data exist for UO{sub 2} or UN within the notional design space for the Prometheus-1 reactor (low fission rate, high temperature, long duration). As such, basic testing is required to validate predictions (and in some cases determine) performance aspects of these fuels. Therefore, the MICE-3B test of UO{sub 2} pellets was designed to provide data on gas release, unrestrained swelling, and restrained swelling at the upper range of fission rates expected for a space reactor. These data would be compared with model predictions and used to determine adequacy of a space reactor design basis relative to fission gas release and swelling of UO{sub 2} fuel and to assess potential pellet-clad interactions. A primary goal of an irradiation test for UN fuel was to assess performance issues currently associated with this fuel type such as gas release, swelling and transient performance. Information learned from this effort may have enabled use of UN fuel for future applications.

  12. Independent deterministic analysis of the operational event with turbine valve closure and one atmospheric dump valve stuck open

    International Nuclear Information System (INIS)

    Rijova, N.

    2007-01-01

    The paper presents the results of the independent analysis of the operational event which took place on 07.11.2003 at Unit 1 of Rostov NPP. The event started with switching off the electrical generator of the turbine due to a short cut at the local switching substation. The turbine isolating valves closed to prevent damage of the turbine. The condenser dump valves (BRU-K) and the atmospheric dump valves (BRU-A) opened to release the vapour generated in the steam generators. After the pressure decrease in the steam generators BRU-K and BRU-A closed but one valve stuck opened. The emergency core cooling system was activated automatically. The main circulation pump of the loop corresponding to the steam generator with the stuck BRU-A was tripped. The stuck valve was closed by the operational stuff manually. No safety limits were violated. The analysis of the event was carried out using ATHLET code. A reasonable agreement was achieved between the calculated and measured values. (author)

  13. Posterior Urethral Valves

    Directory of Open Access Journals (Sweden)

    Steve J. Hodges

    2009-01-01

    Full Text Available The most common cause of lower urinary tract obstruction in male infants is posterior urethral valves. Although the incidence has remained stable, the neonatal mortality for this disorder has improved due to early diagnosis and intensive neonatal care, thanks in part to the widespread use of prenatal ultrasound evaluations. In fact, the most common reason for the diagnosis of posterior urethral valves presently is the evaluation of infants for prenatal hydronephrosis. Since these children are often diagnosed early, the urethral obstruction can be alleviated rapidly through catheter insertion and eventual surgery, and their metabolic derangements can be normalized without delay, avoiding preventable infant mortality. Of the children that survive, however, early diagnosis has not had much effect on their long-term prognosis, as 30% still develop renal insufficiency before adolescence. A better understanding of the exact cause of the congenital obstruction of the male posterior urethra, prevention of postnatal bladder and renal injury, and the development of safe methods to treat urethral obstruction prenatally (and thereby avoiding the bladder and renal damage due to obstructive uropathy are the goals for the care of children with posterior urethral valves[1].

  14. Anterior Urethral Valves

    Directory of Open Access Journals (Sweden)

    Vidyadhar P. Mali

    2006-07-01

    Full Text Available We studied the clinical presentation and management of four patients with anterior urethral valves; a rare cause of urethral obstruction in male children. One patient presented antenatally with oligohydramnios, bilateral hydronephrosis and bladder thickening suggestive of an infravesical obstruction. Two other patients presented postnatally at 1 and 2 years of age, respectively, with poor stream of urine since birth. The fourth patient presented at 9 years with frequency and dysuria. Diagnosis was established on either micturating cystourethrogram (MCU (in 2 or on cystoscopy (in 2. All patients had cystoscopic ablation of the valves. One patient developed a postablation stricture that was resected with an end-to-end urethroplasty. He had an associated bilateral vesicoureteric junction (VUJ obstruction for which a bilateral ureteric reimplantation was done at the same time. On long-term follow-up, all patients demonstrated a good stream of urine. The renal function is normal. Patients are continent and free of urinary infections. Anterior urethral valves are rare obstructive lesions in male children. The degree of obstruction is variable, and so they may present with mild micturition difficulty or severe obstruction with hydroureteronephrosis and renal impairment. Hence, it is important to evaluate the anterior urethra in any male child with suspected infravesical obstruction. The diagnosis is established by MCU or cystoscopy and the treatment is always surgical, either a transurethral ablation or an open resection. The long-term prognosis is good.

  15. The tightness of the globe valves in the exploitations practice of the gas pipe-lines

    International Nuclear Information System (INIS)

    Pietrak, T.; Rudzki, Z.; Surmacz, W.

    2006-01-01

    Technological units of the Transit Gas Pipeline (i.e. Compressor Stations, Valve Stations, Stations or National Network Service Installations) have been fitted with Ball Valves as shut-off devices (block valves). Internal tightness of the valves' seat becomes major factor in securing proper service conditions during normal pipeline operation as well as for isolating of pipeline sections in emergency situations (loss of pipeline integrity or uncontrolled gas escape). Internal tightness of the valves is being inspected during scheduled maintenance of the pipeline units. Any leak revealed during inspection is being repaired, following instructions provided in the Manufacturer's Valve Manual. After a time, some cases have been identified, when repair of the revealed leak was found to be difficult, despite close following of the repair manuals. The paper presents analysis of the issue and corrective actions taken accordingly. (authors)

  16. Fast-Valving of Large Steam Turbine Units as a Means of Power System Security Enhancement

    Directory of Open Access Journals (Sweden)

    Bogdan Sobczak

    2014-03-01

    Full Text Available Fast-valving assists in maintaining system stability following a severe transmission system fault by reducing the turbine mechanical power. Fast-valving consists in rapid closing and opening of steam valves in an adequate manner to reduce the generator accelerating power following the recognition of a severe fault. FV can be an effective and economical method of meeting the performance requirements of a power system in the presence of an increase in wind and solar generation in the power system, newly connected large thermal units and delaying of building new transmission lines. The principle of fast-valving and advantages of applying this technique in large steam turbine units was presented in the paper. Effectiveness of fast-valving in enhancing the stability of the Polish Power Grid was analyzed. The feasibility study of fast-valving application in the 560 MW unit in Kozienice Power Station (EW SA was discussed.

  17. Fracturing mechanics before valve-in-valve therapy of small aortic bioprosthetic heart valves.

    Science.gov (United States)

    Johansen, Peter; Engholt, Henrik; Tang, Mariann; Nybo, Rasmus F; Rasmussen, Per D; Nielsen-Kudsk, Jens Erik

    2017-10-13

    Patients with degraded bioprosthetic heart valves (BHV) who are not candidates for valve replacement may benefit from transcatheter valve-in-valve (VIV) therapy. However, in smaller-sized surgical BHV the resultant orifice may become too narrow. To overcome this, the valve frame can be fractured by a high-pressure balloon prior to VIV. However, knowledge on fracture pressures and mechanics are prerequisites. The aim of this study was to identify the fracture pressures needed in BHV, and to describe the fracture mechanics. Commonly used BHV of small sizes were mounted on a high-pressure balloon situated in a biplane fluoroscopic system with a high-speed camera. The instant of fracture was captured along with the balloon pressure. The valves were inspected for material protrusion and later dissected for fracture zone investigation and description. The valves with a polymer frame fractured at a lower pressure (8-10 atm) than those with a metal stent (19-26 atm). None of the fractured valves had elements protruding. VIV procedures in small-sized BHV may be performed after prior fracture of the valve frame by high-pressure balloon dilatation. This study provides tentative guidelines for expected balloon sizes and pressures for valve fracturing.

  18. Study of a Fuel Supply Pump with a Piezoelectric Effect for Microdirect Alcohol Fuel Cells

    Directory of Open Access Journals (Sweden)

    Hsiao-Kang Ma

    2011-01-01

    Full Text Available A novel design for an ethanol injection system has been proposed, which consists of one pump chamber, two valves, and one central-vibrating piezoelectric device. The system uses a microdiaphragm pump with a piezoelectric device for microdirect alcohol fuel cells. The diameters of the pump chamber are 31 mm and 23 mm, and the depths of the chamber are 1 mm and 2 mm. When the piezoelectric device actuates for changing pump chamber volume, the valves will be opened/closed, and the ethanol will be delivered into DAFC system due to the pressure variation. The chamber dimensions, vibrating frequencies of the piezoelectric device, and valve thickness are used as important parameters for the performance of the novel ethanol injection system. The experimental results show that the ethanol flow rate can reach 170 mL/min at a vibrating frequency of 75 Hz. In addition, the ethanol flow rate is higher than the water flow rate.

  19. Development of a control system for compression and expansion cycles of critical valve for high vacuum systems

    Energy Technology Data Exchange (ETDEWEB)

    Agarwal, Jyoti, E-mail: jagarwal@ipr.res.in; Sharma, H.; Patel, Haresh; Gangradey, R.; Lambade, Vrushabh

    2016-11-15

    Highlights: • Control system with feedback loop of pressure gauge is developed for measuring the life cycle of vacuum isolation valve. • GUI based software developed for easy use and handling of control system. • Control system tested with an experiment showcasing the capability of the control system. • Control system can operate valve based on pressure inside the chamber, which helps to know the degradation of sealing capabilities of valve. • Control system can monitor the total closing and opening time of valve, cycles and pressure inside the vessel. - Abstract: A control system with feedback loop is designed, developed and tested to monitor the life cycles of the axial valve and bellows used in vacuum valves. The control system monitors number of compression cycles of any bellow or closing and opening cycle of a valve. It also interfaces vacuum gauges or pressure gauges to get pressure values inside the system. To find life cycle of valve, the developed control and monitoring system is integrated with an axial valve experimental test set up. In this system, feedback from the vacuum gauge attached to valve enclosure, is given and the life cycle test is automated. This paper describes the control and monitoring system in details and briefs the experiment carried out for valve life cycle. The same system can be used for life cycle estimate for bellows. A suitable GUI is also developed to control the function of the components and resister the number of cycles.

  20. Design and CFD analysis of intake port and exhaust port for a 4 valve cylinder head engine

    Science.gov (United States)

    Latheesh, V. M.; Parthasarathy, P.; Baskaran, V.; Karthikeyan, S.

    2018-02-01

    In cylinder air motion in a compression ignition engine effects mixing of air-fuel, quality of combustion and emission produced. The primary objective is to design and analyze intake and the exhaust port for a four valve cylinder head to meet higher emission norms for a given diesel engine with two valves. In this work, an existing cylinder head designed for two valves was redesigned with 4 valves. The modern trend also confirms this approach. This is being followed in the design and development of new generation engines to meet the stringent environment norms, competition in market and demand for more fuel-efficient engines. The swirl ratio and flow coefficient were measured for different valve lifts using STAR CCM+. CFD results were validated with the two-valve cylinder experimental results. After validation, a comparison between two-valve and four-valve cylinder head was done. The conversion of two valve cylinder head to 4 valves may not support modern high swirl generating port layout and requires a trade-off between many design parameters.

  1. Automatic fire hydrant valve development

    International Nuclear Information System (INIS)

    Drumheller, K.

    1976-01-01

    The development of a remotely-controlled valve to operate a fire hydrant is described. Assembled from off-the-shelf components, the prototype illustrates that a valve light enough to be handled by one man is possible. However, it does not have the ruggedness or reliability needed for actual fire-fighting operations. Preliminary testing by City of Tacoma fire department personnel indicates that the valve may indeed contribute significantly to fire-fighting efficiency

  2. [Ahmed valve in glaucoma surgery].

    Science.gov (United States)

    Bikbov, M M; Khusnitdinov, I I

    This is a review on Ahmed valve application in glaucoma surgery. It contains, in particular, data on the Ahmed valve efficiency, results of experimental and histological studies of filtering bleb encapsulation, examines the use of antimetabolites and anti-VEGF agents, and discusses implantation techniques. The current appraisal of antimetabolites delivery systems integrated into the Ahmed valve is presented. Various complications encountered in practice and preventive measures are also covered.

  3. Thermal fatigue behavior of valves

    International Nuclear Information System (INIS)

    Moinereau, D.; Scliffet, L.; Capion, J.C.; Genette, P.

    1991-01-01

    This paper reports that valves of pressurized water reactors are exposed to thermal shocks during transient operations. The numerous thermal shock tests performed on valves on the EDF test facilities have shown the sensibility of fillets and geometrical discontinuities to thermal fatigue: cracks can appear in those areas and grow through the valve body. Valves systems designated as level 1 must be designed to withstand fatigue up to the second isolation valve: the relevant rule is specified in the paragraph B 3500 of the French RCCM code. It is a simplified method which doesn't require finite element calculations. Many valve systems have been designed according to this rule and have been operated without accident. However, in one case, important cracks were found in the fillet of a check-valve after numerous thermal shocks. Calculation of the valve's behavior according to the RCCM code to estimate the fatigue damage resulting from thermal shocks led to a low damage factor, which doesn't agree with the experimental results. This was confirmed by new testings and showed the inadequacy of B 3500 rule for thermal transients. On this base a new rule is proposed to estimate fatigue damage resulting from thermal shocks. An experimental program has been realized to validate this rule. Axisymetrical analytical mock-ups with different geometries and one check-valve in austenitic stainless steel 316 L have been submitted to hot thermal shocks of 210 degrees C magnitude

  4. Fluid mechanics of heart valves.

    Science.gov (United States)

    Yoganathan, Ajit P; He, Zhaoming; Casey Jones, S

    2004-01-01

    Valvular heart disease is a life-threatening disease that afflicts millions of people worldwide and leads to approximately 250,000 valve repairs and/or replacements each year. Malfunction of a native valve impairs its efficient fluid mechanic/hemodynamic performance. Artificial heart valves have been used since 1960 to replace diseased native valves and have saved millions of lives. Unfortunately, despite four decades of use, these devices are less than ideal and lead to many complications. Many of these complications/problems are directly related to the fluid mechanics associated with the various mechanical and bioprosthetic valve designs. This review focuses on the state-of-the-art experimental and computational fluid mechanics of native and prosthetic heart valves in current clinical use. The fluid dynamic performance characteristics of caged-ball, tilting-disc, bileaflet mechanical valves and porcine and pericardial stented and nonstented bioprostheic valves are reviewed. Other issues related to heart valve performance, such as biomaterials, solid mechanics, tissue mechanics, and durability, are not addressed in this review.

  5. Surge-damping vacuum valve

    International Nuclear Information System (INIS)

    Bullock, J.C.; Kelley, B.E.

    1977-01-01

    A valve for damping out flow surges in a vacuum system is described. The surge-damping mechanism consists of a slotted, spring-loaded disk adjacent to the valve's vacuum port (the flow passage to the vacuum roughing pump). Under flow surge conditions, the differential pressure forces the disk into a sealing engagement with the vacuum port, thereby restricting the gas flow path to narrow slots in the disk's periphery. The increased flow damps out the flow surge. When pressure is equalized on both sides of the valve, the spring load moves the disk away from the port to restore full flow conductance through the valve

  6. Low Load Limit Extension for Gasoline Compression Ignition Using Negative Valve Overlap Strategy

    KAUST Repository

    Vallinayagam, R.

    2018-04-03

    Gasoline compression ignition (GCI) is widely studied for the benefits of simultaneous reduction in nitrogen oxide (NO) and soot emissions without compromising the engine efficiency. Despite this advantage, the operational range for GCI is not widely expanded, as the auto-ignition of fuel at low load condition is difficult. The present study aims to extend the low load operational limit for GCI using negative valve overlap (NVO) strategy. The engine used for the current experimentation is a single cylinder diesel engine that runs at an idle speed of 800 rpm with a compression ratio of 17.3. The engine is operated at homogeneous charge compression ignition (HCCI) and partially premixed combustion (PPC) combustion modes with the corresponding start of injection (SOI) at 180 CAD (aTDC) and 30 CAD (aTDC), respectively. In the presented work, intake air temperature is used as control parameter to maintain combustion stability at idle and low load condition, while the intake air pressure is maintained at 1 bar (ambient). The engine is equipped with variable valve cam phasers that can phase both inlet and exhaust valves from the original timing. For the maximum cam phasing range (56 CAD) at a valve lift of 0.3 mm, the maximum allowable positive valve overlap was 20 CAD. In the present study, the exhaust cam is phased to 26 CAD and 6 CAD and the corresponding NVO is noted to be 10 CAD and 30 CAD, respectively. With exhaust cam phasing adjustment, the exhaust valve is closed early to retain hot residual gases inside the cylinder. As such, the in-cylinder temperature is increased and a reduction in the required intake air temperature to control combustion phasing is possible. For a constant combustion phasing of 3 CAD (aTDC), a minimum load of indicated mean effective pressure (IMEP) = 1 bar is attained for gasoline (RON = 91) at HCCI and PPC modes. The coefficient of variance was observed to below 5% at these idle and low load conditions. At the minimum load point, the

  7. A study of waste and delivery valve design modification to the pump performance

    Science.gov (United States)

    Harith, M. N.; Bakar, R. A.; Ramasamy, D.; Kardigama, K.; Quanjin, Ma

    2018-04-01

    This paper objective is to share design revolution of waste and delivery valve that contribute to the overall pump performance. In this paper, 3 new designs of waste and delivery valve pump are presented with comprehensive internal flow analysis using computational fluid dynamics (CFD) simulation over 4 cases that have been deeply study for one of the design chosen. 4 cases involving opening and closing both valve or either one. 0.265m height size of customized waste valve with an opening limiter and spring was used to demonstrate cyclic closing and opening valve operation extended up to 0.164m gap. Based on result, this characteristics contribute to 10-20% waste water reduction and enhancement of flow rate height up to 80m. Apart from that this paper also share some of pressure (dynamic, total, static), velocity (x, y, z axis) simulation including the vector flow were under different flow cases.

  8. Heart Valve Surgery Recovery and Follow Up

    Science.gov (United States)

    ... Guide: Understanding Your Heart Valve Problem | Spanish Symptom Tracker | Spanish Pre-surgery Checklist | Spanish What Is Heart ... Heart Valves • Heart Valve Problems and Causes • Risks, Signs and Symptoms • Accurate Diagnosis • Treatment Options • Recovery and ...

  9. Tissue engineering of heart valves: in vitro experiences.

    Science.gov (United States)

    Sodian, R; Hoerstrup, S P; Sperling, J S; Daebritz, S H; Martin, D P; Schoen, F J; Vacanti, J P; Mayer, J E

    2000-07-01

    Tissue engineering is a new approach, whereby techniques are being developed to transplant autologous cells onto biodegradable scaffolds to ultimately form new functional tissue in vitro and in vivo. Our laboratory has focused on the tissue engineering of heart valves, and we have fabricated a trileaflet heart valve scaffold from a biodegradable polymer, a polyhydroxyalkanoate. In this experiment we evaluated the suitability of this scaffold material as well as in vitro conditioning to create viable tissue for tissue engineering of a trileaflet heart valve. We constructed a biodegradable and biocompatible trileaflet heart valve scaffold from a porous polyhydroxyalkanoate (Meatabolix Inc, Cambridge, MA). The scaffold consisted of a cylindrical stent (1 x 15 x 20 mm inner diameter) and leaflets (0.3 mm thick), which were attached to the stent by thermal processing techniques. The porous heart valve scaffold (pore size 100 to 240 microm) was seeded with vascular cells grown and expanded from an ovine carotid artery and placed into a pulsatile flow bioreactor for 1, 4, and 8 days. Analysis of the engineered tissue included biochemical examination, enviromental scanning electron microscopy, and histology. It was possible to create a trileaflet heart valve scaffold from polyhydroxyalkanoate, which opened and closed synchronously in a pulsatile flow bioreactor. The cells grew into the pores and formed a confluent layer after incubation and pulsatile flow exposure. The cells were mostly viable and formed connective tissue between the inside and the outside of the porous heart valve scaffold. Additionally, we demonstrated cell proliferation (DNA assay) and the capacity to generate collagen as measured by hydroxyproline assay and movat-stained glycosaminoglycans under in vitro pulsatile flow conditions. Polyhydroxyalkanoates can be used to fabricate a porous, biodegradable heart valve scaffold. The cells appear to be viable and extracellular matrix formation was induced

  10. A novel magnetic valve using room temperature magnetocaloric materials

    DEFF Research Database (Denmark)

    Eriksen, Dan; Bahl, Christian; Pryds, Nini

    2012-01-01

    changes. This is made possible by the strong temperature dependence of the magnetization close to the Curie temperature of the magnetocaloric materials. Different compositions of both La0.67(Ca,Sr)0.33MnO3 and La(Fe,Co,Si)13 have been considered for use in prototype valves. Based on measured magnetization...

  11. On the feasibility of detecting flaws in artificial heart valves

    NARCIS (Netherlands)

    Lepelaars, E.S.A.M.; Ooijen, van W.D.R.; Tijhuis, A.G.

    2000-01-01

    Investigates the feasibility of detecting defects in certain artificial heart valves by determining the electromagnetic behavior of some simple models with the aid of thin-wire integral equations. The idea is to use the stationary current that occurs at late times after the excitation of a closed

  12. The patient inflating valve in anaesthesia and resuscitation breathing systems.

    Science.gov (United States)

    Fenton, P M; Bell, G

    2013-03-01

    Patient inflating valves combined with self-inflating bags are known to all anaesthetists as resuscitation devices and are familiar as components of draw-over anaesthesia systems. Their variants are also commonplace in transfer and home ventilators. However, the many variations in structure and function have led to difficulties in their optimal use, definition and classification. After reviewing the relevant literature, we defined a patient inflating valve as a one-way valve that closes an exit port to enable lung inflation, also permitting exhalation and spontaneous breathing, the actions being automatic. We present a new classification based on the mechanism of valve opening/closure; namely elastic recoil of a flexible flap/diaphragm, sliding spindle opened by a spring/magnet or a hollow balloon collapsed by external pressure. The evolution of these valves has been driven by the difficulties documented in critical incidents, which we have used along with information from modern International Organization for Standardization standards to identify 13 ideal properties, the top six of which are non-jamming, automatic, no bypass effect, no rebreathing or air entry at patient end, low resistance, robust and easy to service. The Ambu and the Laerdal valves have remained popular due to their simplicity and reliability. Two new alternatives, the Fenton and Diamedica valves, offer the benefits of location away from the patient while retaining a small functional dead space. They also offer the potential for greater use of hybrid continuous flow/draw-over systems that can operate close to atmospheric pressure. The reliable application of positive end-expiratory pressure/continuous positive airway pressure remains a challenge.

  13. The Impact of Vacuum Gate Valves on the LHC Beam

    CERN Document Server

    Appleby, R B; Cerutti, F; Ferrari, A; Mauri, M; Vlachoudis, V

    2009-01-01

    The LHC vacuum sector valves are located in the straight sections of the LHC ring, and designed to sectorize the LHC vacuum. The valves are interlocked and should trigger a beam dump request if they close on a circulating beam. This report studies the impact on the machine if this request is not made and the valve scrapes the LHC beam halo. Cascade calculations are made using a model of IR7, with several different valve locations, to calculate the downstream energy deposition in superconducting magnet coils and the corresponding signal in beam loss monitors at the quench level. The calculations are done at 7, 5, and 3.5 TeV. It is found that when a downstream magnet reaches the quench level, the neighbouring BLMs see a signal well above the detection threshold. Furthermore, the BLM signal is consistent with the BLM applied threshold settings and a signal is seen in the time domain before the quench level is reached. Therefore the report concludes that the BLMs can see the closing valve and trigger a beam dump...

  14. Sibling cycle piston and valving method

    Science.gov (United States)

    Mitchell, Matthew P. (Inventor); Bauwens, Luc (Inventor)

    1990-01-01

    A double-acting, rotating piston reciprocating in a cylinder with the motion of the piston providing the valving action of the Sibling Cycle through the medium of passages between the piston and cylinder wall. The rotating piston contains regenerators ported to the walls of the piston. The piston fits closely in the cylinder at each end of the cylinder except in areas where the wall of the cylinder is relieved to provide passages between the cylinder wall and the piston leading to the expansion and compression spaces, respectively. The piston reciprocates as it rotates. The cylinder and piston together comprise an integral valve that seqentially opens and closes the ports at the ends of the regenerators alternately allowing them to communicate with the expansion space and compression space and blocking that communication. The relieved passages in the cylinder and the ports in the piston are so arranged that each regenerator is sequentially (1) charged with compressed working gas from the compression space; (2) isolated from both expansion and compression spaces; (3) discharged of working gas into the expansion space; and (4) simultaneously charged with working gas from the expansion space while being discharged of working gas into the compression space, in the manner of the Sibling Cycle. In an alterate embodiment, heat exchangers are external to the cylinder and ports in the cylinder wall are alternately closed by the wall of the piston and opened to the expansion and compression spaces through relieved passages in the wall of the reciprocating, rotating piston.

  15. Sensor system for fuel transport vehicle

    Science.gov (United States)

    Earl, Dennis Duncan; McIntyre, Timothy J.; West, David L.

    2016-03-22

    An exemplary sensor system for a fuel transport vehicle can comprise a fuel marker sensor positioned between a fuel storage chamber of the vehicle and an access valve for the fuel storage chamber of the vehicle. The fuel marker sensor can be configured to measure one or more characteristics of one or more fuel markers present in the fuel adjacent the sensor, such as when the marked fuel is unloaded at a retail station. The one or more characteristics can comprise concentration and/or identity of the one or more fuel markers in the fuel. Based on the measured characteristics of the one or more fuel markers, the sensor system can identify the fuel and/or can determine whether the fuel has been adulterated after the marked fuel was last measured, such as when the marked fuel was loaded into the vehicle.

  16. 241-AN-A valve pit manifold valves and position indication acceptance test procedure

    Energy Technology Data Exchange (ETDEWEB)

    VANDYKE, D.W.

    1999-08-25

    This document describes the method used to test design criteria for gear actuated ball valves installed in 241-AN-A Valve Pit located at 200E Tank Farms. The purpose of this procedure is to demonstrate the following: Equipment is properly installed, labeled, and documented on As-Built drawings; New Manifold Valves in the 241-AN-A Valve Pit are fully operable using the handwheel of the valve operators; New valve position indicators on the valve operators will show correct valve positions; New valve position switches will function properly; and New valve locking devices function properly.

  17. Design and performance of General Electric boiling water reactor main steam line isolation valves

    International Nuclear Information System (INIS)

    Rockwell, D.A.; van Zylstra, E.H.

    1976-08-01

    An extensive test program has been completed by the General Electric Company in cooperation with the Commonwealth Edison Company on the basic design type of large main steam line isolation valves used on General Electric Boiling Water Reactors. Based on a total of 40 tests under simulated accident conditions covering a wide range of mass flows, mixture qualities, and closing times, it was concluded that the commercially available valves of this basic type will close completely and reliably as required. Analytical methods to predict transient effects in the steam line and valve after postulated breaks were refined and confirmed by the test program

  18. Design Optimization of Moving Magnet Actuated Valves for Digital Displacement Machines

    DEFF Research Database (Denmark)

    Madsen, Esben Lundø; Jørgensen, Janus Martin Thastum; Nørgård, Christian

    2017-01-01

    High-efficiency hydraulic machines using digital valves are presently a topic of great focus. Digital valve performance with respect to pressure loss, closing time as well as electrical power consumption, is key to obtaining high efficiency. A recent digital seat valve design developed at Aalborg...... optimized design closes in 2.1 ms, has a pressure drop of 0.8 bar at 150 l/min and yields a digital displacement machine average chamber efficiency of 98.9%. The design is simple in construction and uses a single coil, positioned outside the pressure chamber, eliminating the need for an electrical interface...

  19. Plant experience with check valves in passive systems

    Energy Technology Data Exchange (ETDEWEB)

    Pahladsingh, R R [GKN Joint Nuclear Power Plant, Dodewaard (Netherlands)

    1996-12-01

    In the design of the advanced nuclear reactors there is a tendency to introduce more passive safety systems. The 25 year old design of the GKN nuclear reactor is different from the present BWR reactors because of some special features, such as the Natural Circulation - and the Passive Isolation Condenser system. When reviewing the design, one can conclude that the plant has 25 years of experience with check valves in passive systems and as passive components in systems. The result of this experience has been modeled in a plant-specific ``living PSA`` for the plant. A data-analysis has been performed on components which are related to the safety systems in the plant. As part of this study also the check valves have been taken in consideration. At GKN, the check valves have shown to be reliable components in the systems and no catastrophic failures have been experienced during the 25 years of operation. Especially the Isolation Condenser with its operation experience can contribute substantially to the insight of check valves in stand-by position at reactor pressure and operating by gravity under different pressure conditions. With the introduction of several passive systems in the SBWR-600 design, such as the Isolation Condensers, Gravity Driven Cooling, and Suppression Pool Cooling System, the issue of reliability of check valves in these systems is actual. Some critical aspects for study in connection with check valves are: What is the reliability of a check valve in a system at reactor pressure, to open on demand; what is the reliability of a check valve in a system at low pressure (gravity), to open on demand; what is the reliability of a check valve to open/close when the stand-by check wave is at zero differential pressure. The plant experience with check valves in a few essential safety systems is described and a brief introduction will be made about the application of check valves in the design of the new generation reactors is given. (author). 6 figs, 1 tab.

  20. Hydrogen-Oxygen PEM Regenerative Fuel Cell at NASA Glenn Research Center

    Science.gov (United States)

    Bents, David J.

    2004-01-01

    The NASA Glenn Research Center has constructed a closed-cycle hydrogen-oxygen PEM regenerative fuel cell (RFC) to explore its potential use as an energy storage device for a high altitude solar electric aircraft. Built up over the last 2 years from specialized hardware and off the shelf components the Glenn RFC is a complete "brassboard" energy storage system which includes all the equipment required to (1) absorb electrical power from an outside source and store it as pressurized hydrogen and oxygen and (2) make electrical power from the stored gases, saving the product water for re-use during the next cycle. It consists of a dedicated hydrogen-oxygen fuel cell stack and an electrolyzer stack, the interconnecting plumbing and valves, cooling pumps, water transfer pumps, gas recirculation pumps, phase separators, storage tanks for oxygen (O2) and hydrogen (H2), heat exchangers, isolation valves, pressure regulators, nitrogen purge provisions, instrumentation, and other components. It specific developmental functions include: (1) Test fuel cells and fuel cell components under repeated closed-cycle operation (nothing escapes; everything is used over and over again). (2) Simulate diurnal charge-discharge cycles (3) Observe long-term system performance and identify degradation and loss mechanisms. (4) Develop safe and convenient operation and control strategies leading to the successful development of mission-capable, flight-weight RFC's.

  1. Aortic valve replacement

    DEFF Research Database (Denmark)

    Kapetanakis, Emmanouil I; Athanasiou, Thanos; Mestres, Carlos A

    2008-01-01

    mortality were collected. Group analysis by patient geographic distribution and by annular diameter of the prosthesis utilized was conducted. Patients with a manufacturer's labeled prosthesis size > or = 21 mm were assigned to the 'large' aortic size subset, while those with a prosthesis size ... differences in the distribution of either gender or BSA. In the multivariable model, south European patients were seven times more likely to receive a smaller-sized aortic valve (OR = 6.5, 95% CI = 4.82-8.83, p

  2. BNGS B valve packing program

    International Nuclear Information System (INIS)

    Cumming, D.

    1995-01-01

    The Bruce B Valve Packing Program began in 1987. The early history and development were presented at the 1992 International CANDU Maintenance conference. This presentation covers the evolution of the Bruce B Valve Packing Program over the period 1992 to 1995. (author)

  3. Experience with valves for PHWR reactors

    International Nuclear Information System (INIS)

    Narayan, K.; Mhetre, S.G.

    1977-01-01

    Material specifications and inspection and testing requirements of the valves meant for use in nuclear reactors are mentioned. In the heavy water systems (both primary and moderator) of a PHWR type reactor, the valves used are gate valves, globe valves, diaphragm valves, butterfly valves, check valves and relief valves. Their locations and functions they perform in the Rajasthan Atomic Power Station Unit-1 are described. Experience with them is given. The major problems encountered with them have been : (1) leakage from the stem seals and body bonnet joint, (2) leakage due to failure of diaphragm and/or washout of the packing and (3) malfunctioning. Measures taken to solve these are discussed. Finally a mention has been made of improved versions of valves, namely, metal diaphragm valve and inverted relief valve. (M.G.B.)

  4. Testing of valves and associated systems in large scale experiments

    International Nuclear Information System (INIS)

    Becker, M.

    1985-01-01

    The system examples dealt with are selected so that they cover a wide spectrum of technical tasks and limits. Therefore the flowing medium varies from pure steam flow via a mixed flow of steam and water to pure water flow. The valves concerned include those whose main function is opening, and also those whose main function is the secure closing. There is a certain limitation in that the examples are taken from Boiling Water Reactor technology. The main procedure in valve and system testing described is, of course, not limited to the selected examples, but applies generally in powerstation and process technology. (orig./HAG) [de

  5. Characterizations of gas purge valves for liquid alignment and gas removal in a microfluidic chip

    International Nuclear Information System (INIS)

    Chuang, Han-Sheng; Thakur, Raviraj; Wereley, Steven T

    2012-01-01

    Two polydimethylsiloxane (PDMS) gas purge valves for excessive gas removal in general lab-on-a-chip applications are presented in this paper. Both valves are devised based on a three-layer configuration comprising a top layer for liquid channels, a membrane and a bottom layer for gas channels. The pneumatic valves work as a normal gateway for fluids when the membrane is bulged down (open state) by vacuum or pushed up (closed state) by pressure. In the closed state, the air in front of a liquid can be removed through a small notch or a permeable PDMS membrane by compressing the liquid. The purge valve with a small notch across its valve seat, termed surface-tension (ST) valve, can be operated with pressure under 11.5 kPa. The liquid is mainly retained by the surface tension resulting from the hydrophobic channel walls. In contrast, the purge valve with vacuum-filled grooves adjacent to a liquid channel, termed gas-permeation (GP) valve, can be operated at pressure above 5.5 kPa. Based on the principle of gas permeation, the excessive air can be slowly removed through the vent grooves. Detailed evaluations of both valves in a pneumatically driven microfluidic chip were conducted. Specifically, the purge valves enable users to remove gas and passively align liquids at desired locations without using sensing devices or feedback circuits. Finally, a rapid mixing reaction was successfully performed with the GP valves, showing their practicability as incorporated in a microfluidic chip. (paper)

  6. FAILURE MODE AND EFFECT ANALYSIS (FMEA OF BUTTERFLY VALVE IN OIL AND GAS INDUSTRY

    Directory of Open Access Journals (Sweden)

    MUHAMMAD AMIRUL BIN YUSOF

    2016-04-01

    Full Text Available Butterfly valves are mostly used in various industries such as oil and gas plant. This valve operates with rotating motion using pneumatic system. Rotating actuator turns the disc either parallel or perpendicular to the flow. When the valve is fully open, the disc is rotated a quarter turn so that it allows free passage of the fluid and when fully closed, the disc rotated a quarter turns to block the fluid. The primary failure modes for valves are the valve leaks to environment through flanges, seals on the valve body, valve stem packing not properly protected, over tightened packing nuts, the valve cracks and leaks over the seat. To identify the failure of valve Failure Mode and Effects Analysis has been chosen. FMEA is the one of technique to perform failure analysis. It involves reviewing as many components to identify failure modes, and their causes and effects. For each component, the failure modes and their resulting effects on the rest of the system are recorded in a specific FMEA form. Risk priority number, severity, detection, occurrence are the factor determined in this studies. Risk priority number helps to find out the highest hazardous activities which need more attention than the other activity. The highest score of risk priority number in this research is seat. Action plan was proposed to reduce the risk priority number and so that potential failures also will be reduced.

  7. Overview of Prevention for Water Hammer by Check Valve Action in Nuclear Reactor

    International Nuclear Information System (INIS)

    Kim, Dayong; Yoon, Hyungi; Seo, Kyoungwoo; Kim, Seonhoon

    2016-01-01

    Water hammer can cause serious damage to pumping system and unexpected system pressure rise in the pipeline. In nuclear reactor, water hammer can influence on the integrity of safety related system. Water hammer in nuclear reactor have been caused by voiding in normally water-filled lines, steam condensation line containing both steam and water, as well as by rapid check valve action. Therefore, this study focuses on the water hammer by check valve among the sources of water hammer occurrence and suggests proper methodology for check valve type selection against water hammer. This study focuses on the water hammer by check valve action among the sources of water hammer occurrence and suggests proper methodology for check valve type selection against water hammer. If the inadvertent pump trip or pipe rupture in high velocity and pressure pipe is predicted, the fast response check valve such as tiled disc, dual disc and nozzle check valve should be installed in the system. If the inadvertent pump trip or pipe rupture in very high velocity and pressure pipe and excessively large revered flow velocity are predicted, the very slowly closing check valve such as controlled closure check valve should be installed in the system

  8. Overview of Prevention for Water Hammer by Check Valve Action in Nuclear Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dayong; Yoon, Hyungi; Seo, Kyoungwoo; Kim, Seonhoon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    Water hammer can cause serious damage to pumping system and unexpected system pressure rise in the pipeline. In nuclear reactor, water hammer can influence on the integrity of safety related system. Water hammer in nuclear reactor have been caused by voiding in normally water-filled lines, steam condensation line containing both steam and water, as well as by rapid check valve action. Therefore, this study focuses on the water hammer by check valve among the sources of water hammer occurrence and suggests proper methodology for check valve type selection against water hammer. This study focuses on the water hammer by check valve action among the sources of water hammer occurrence and suggests proper methodology for check valve type selection against water hammer. If the inadvertent pump trip or pipe rupture in high velocity and pressure pipe is predicted, the fast response check valve such as tiled disc, dual disc and nozzle check valve should be installed in the system. If the inadvertent pump trip or pipe rupture in very high velocity and pressure pipe and excessively large revered flow velocity are predicted, the very slowly closing check valve such as controlled closure check valve should be installed in the system.

  9. Prosthetic valve endocarditis after transcatheter aortic valve implantation

    DEFF Research Database (Denmark)

    Olsen, Niels Thue; De Backer, Ole; Thyregod, Hans G H

    2015-01-01

    BACKGROUND: Transcatheter aortic valve implantation (TAVI) is an advancing mode of treatment for inoperable or high-risk patients with aortic stenosis. Prosthetic valve endocarditis (PVE) after TAVI is a serious complication, but only limited data exist on its incidence, outcome, and procedural......%) were treated conservatively and 1 with surgery. Four patients (22%) died from endocarditis or complications to treatment, 2 of those (11%) during initial hospitalization for PVE. An increased risk of TAVI-PVE was seen in patients with low implanted valve position (hazard ratio, 2.8 [1.1-7.2]), moderate...

  10. Identification of black-box linear models : the case of thermal periodic contact of exhaust valves in internal combustion engines

    Energy Technology Data Exchange (ETDEWEB)

    Shojaeefard, M.H.; Fazelpour, M. [Iran Univ. of Science and Technology, Tehran (Iran, Islamic Republic of). Dept. of Automotive Engineering; Goudarzi, K. [Iran Univ. of Science and Technology, Tehran (Iran, Islamic Republic of). Dept. of Mechanical Engineering

    2009-07-01

    In internal combustion engines, hot exhaust gases that pass through the exhaust valve lead to high temperatures in the exhaust valve and the valve seat. Heat must be transferred from the exhaust valve to valve seat as they come in contact with each other during the opening and closing cycle in order to avoid damaging the exhaust valve. The heat transfer rate from the valve to valve seat is a function of many factors, including the thermal contact conductance (TCC) between the valve and valve seat. The objective of this study was to experimentally calculate the TCC for six different frequencies in the quasi-steady-state condition and also to obtain a transfer function to estimate the exhaust valve temperature by using black-box models of system identification. Periodic contact was taken into consideration in the study. The paper presented the experimental setup including the loading system, heat and cooling system, temperature measurement system, specimens properties, and data acquisition system. The paper also described the test procedure and experimental results. System identification was also described. It was concluded that the TCC decreased as the frequency of contact increased. The temperature transfer function was calculated by using the system identification method and having the temperatures at both sides of the contact surface. By knowing the temperature of one rod, the temperature of the other rod was estimated with high accuracy. 16 refs., 4 tabs., 7 figs.

  11. Studies of valve lifter for automotive heavy duty diesel engine by ceramic materials. II. Development of SiC valve lifter by injection molding method

    Energy Technology Data Exchange (ETDEWEB)

    Yun, H W [Technical Centre of KIA-ASIA MOTORS (Korea, Republic of); Han, I S [Korea Institute of Energy Research, Tajeon (Korea, Republic of); Lim, Y S; Chung, Y J [Myong Ji University (Korea, Republic of)

    1998-02-01

    Valve lifter, namely tappet, is supported by lifter hole which is located upper side of camshaft in cylinder block, transforms rotatic movement of camshaft into linear movement and helps to open and shut the engine valve as an engine parts. The face of valve lifter, which is continuously contacting with camshaft, brings about abnormal wears, such as unfair wear and early wear, because it is severely loaded in the valve train system. These wears act as a defect like over-clearance and cause imperfect combustion of fuel during the valve lifting in the combustion chamber. Consequently, this imperfect combustion makes the engine out-put decrease and has cause on air pollution. To prevent these wears, therefore, the valve lifter cast in metal developed into SiC ceramics valve lifter which has an excellence in wear and impact resistance. As a result, the optimum process conditions like injection condition, mixture ratio and debonding process could be established. After sintering, fine-sinered dual microstructure in which prior {alpha}-SiC, carbon and silicon was obtained. Based on the new SiC({beta}-SiC) produced by reaction among the {alpha}-SiC, carbon and silicon was obtained. Based on the study, it is verified that mechanical properties of SiC valve lifter are excellent in Vickers hardness 1100{approx}1200 bending strength (300{approx}350 Pa), fracture toughness (1.5{approx}1.7 MPacentre dotm{sup 1/2}). Through engine dynamo testing, SiC valve lifter and metal valve lifter are examined and compared into abnormal phenomena such early fracture, unfair and early wear. It is hoped that this research will serve as an important springboard for the future study of heavy duty diesel engine parts developed by ceramics which has a good wear resistance, reliability, and lightability.

  12. Fault Diagnosis of Internal Combustion Engine Valve Clearance Using the Impact Commencement Detection Method

    Science.gov (United States)

    Jiang, Zhinong; Wang, Zijia; Zhang, Jinjie

    2017-01-01

    Internal combustion engines (ICEs) are widely used in many important fields. The valve train clearance of an ICE usually exceeds the normal value due to wear or faulty adjustment. This work aims at diagnosing the valve clearance fault based on the vibration signals measured on the engine cylinder heads. The non-stationarity of the ICE operating condition makes it difficult to obtain the nominal baseline, which is always an awkward problem for fault diagnosis. This paper overcomes the problem by inspecting the timing of valve closing impacts, of which the referenced baseline can be obtained by referencing design parameters rather than extraction during healthy conditions. To accurately detect the timing of valve closing impact from vibration signals, we carry out a new method to detect and extract the commencement of the impacts. The results of experiments conducted on a twelve-cylinder ICE test rig show that the approach is capable of extracting the commencement of valve closing impact accurately and using only one feature can give a superior monitoring of valve clearance. With the help of this technique, the valve clearance fault becomes detectable even without the comparison to the baseline, and the changing trend of the clearance could be trackable. PMID:29244722

  13. Fault Diagnosis of Internal Combustion Engine Valve Clearance Using the Impact Commencement Detection Method.

    Science.gov (United States)

    Jiang, Zhinong; Mao, Zhiwei; Wang, Zijia; Zhang, Jinjie

    2017-12-15

    Internal combustion engines (ICEs) are widely used in many important fields. The valve train clearance of an ICE usually exceeds the normal value due to wear or faulty adjustment. This work aims at diagnosing the valve clearance fault based on the vibration signals measured on the engine cylinder heads. The non-stationarity of the ICE operating condition makes it difficult to obtain the nominal baseline, which is always an awkward problem for fault diagnosis. This paper overcomes the problem by inspecting the timing of valve closing impacts, of which the referenced baseline can be obtained by referencing design parameters rather than extraction during healthy conditions. To accurately detect the timing of valve closing impact from vibration signals, we carry out a new method to detect and extract the commencement of the impacts. The results of experiments conducted on a twelve-cylinder ICE test rig show that the approach is capable of extracting the commencement of valve closing impact accurately and using only one feature can give a superior monitoring of valve clearance. With the help of this technique, the valve clearance fault becomes detectable even without the comparison to the baseline, and the changing trend of the clearance could be trackable.

  14. Pump having pistons and valves made of electroactive actuators

    Science.gov (United States)

    Bar-Cohen, Yoseph (Inventor)

    1997-01-01

    The present invention provides a pump for inducing a displacement of a fluid from a first medium to a second medium, including a conduit coupled to the first and second media, a transducing material piston defining a pump chamber in the conduit and being transversely displaceable for increasing a volume of the chamber to extract the fluid from the first medium to the chamber and for decreasing the chamber volume to force the fluid from the chamber to the second medium, a first transducing material valve mounted in the conduit between the piston and the first medium and being transversely displaceable from a closed position to an open position to admit the fluid to the chamber, and control means for changing a first field applied to the piston to displace the piston for changing the chamber volume and for changing a second field applied to the first valve to change the position of the first valve.

  15. Cavitation guide for control valves

    Energy Technology Data Exchange (ETDEWEB)

    Tullis, J.P. [Tullis Engineering Consultants, Logan, UT (United States)

    1993-04-01

    This guide teaches the basic fundamentals of cavitation to provide the reader with an understanding of what causes cavitation, when it occurs, and the potential problems cavitation can cause to a valve and piping system. The document provides guidelines for understanding how to reduce the cavitation and/or select control valves for a cavitating system. The guide provides a method for predicting the cavitation intensity of control valves, and how the effect of cavitation on a system will vary with valve type, valve function, valve size, operating pressure, duration of operation and details of the piping installation. The guide defines six cavitation limits identifying cavitation intensities ranging from inception to the maximum intensity possible. The intensity of the cavitation at each limit Is described, including a brief discussion of how each level of cavitation influences the valve and system. Examples are included to demonstrate how to apply the method, including making both size and pressure scale effects corrections. Methods of controlling cavitation are discussed providing information on various techniques which can be used to design a new system or modify an existing one so it can operate at a desired level of cavitation.

  16. Cavitation guide for control valves

    International Nuclear Information System (INIS)

    Tullis, J.P.

    1993-04-01

    This guide teaches the basic fundamentals of cavitation to provide the reader with an understanding of what causes cavitation, when it occurs, and the potential problems cavitation can cause to a valve and piping system. The document provides guidelines for understanding how to reduce the cavitation and/or select control valves for a cavitating system. The guide provides a method for predicting the cavitation intensity of control valves, and how the effect of cavitation on a system will vary with valve type, valve function, valve size, operating pressure, duration of operation and details of the piping installation. The guide defines six cavitation limits identifying cavitation intensities ranging from inception to the maximum intensity possible. The intensity of the cavitation at each limit Is described, including a brief discussion of how each level of cavitation influences the valve and system. Examples are included to demonstrate how to apply the method, including making both size and pressure scale effects corrections. Methods of controlling cavitation are discussed providing information on various techniques which can be used to design a new system or modify an existing one so it can operate at a desired level of cavitation

  17. Characteristic analysis of servo valve

    International Nuclear Information System (INIS)

    Ko, J. H.; Ryu, D. R.; Lee, J. H.; Kim, Y. S.; Na, J. C.; Kim, D. S.

    2008-01-01

    Electro-pneumatic servo valve is an electro-mechanical device which converts electric signals into a proper pneumatic flow rate or pressure. In order to improve the overall performance of pneumatic servo systems, electro-pneumatic servo valves are required, which have fast dynamic characteristics, no air leakage at a null point, and can be fabricated at a low-cost. The first objective of this research is to design and to fabricate a new electro-pneumatic servo valve which satisfies the above-mentioned requirements. In order to design the mechanism of the servo valve optimally, the flow inside the valve depending upon the position of spool was analyzed variously, and on the basis of such analysis results, the valve mechanism, which was formed by combination of the spool and the sleeve, was designed and manufactured. And a tester for conducting an overall performance test was designed and manufactured, and as a result of conducting the flow rate test, the pressure test and the frequency test on the developed pneumatic servo valve

  18. Developments in mechanical heart valve prosthesis

    Indian Academy of Sciences (India)

    Artificial heart valves are engineered devices used for replacing diseased or damaged natural valves of the heart. Most commonly used for replacement are mechanical heart valves and biological valves. This paper briefly outlines the evolution, designs employed, materials being used,. and important factors that affect the ...

  19. Production of a refined biooil derived by fast pyrolysis of chicken manure with chemical and physical characteristics close to those of fossil fuels.

    Science.gov (United States)

    Monreal, Carlos M; Schnitzer, Morris

    2011-01-01

    The chemical and physical properties of raw biooils prevent their direct use in combustion engines. We processed raw pyrolytic biooil derived from chicken manure to yield a colorless refined biooil with diesel qualities. Chemical characterization of the refined biooil involved elemental and several spectroscopic analyses. The physical measurements employed were viscosity, density and heat of combustion. The elemental composition (% wt/wt) of the refined biooil was 82.7 % C, 15.3 % H, 0.2 % N and 1.8 % O, no S. Its viscosity was 0.006 Pa.s and a heat of combustion of 43 MJ kg(-1). The refined biooil fraction contains n-alkanes, ranging from n-C(14) to n-C(27), alkenes varying from C(10:1) to C(22:1), and long-chain alcohols. The refined biooil makes a good diesel fuel due to its chemical and physical properties.

  20. Transcatheter Mitral Valve-in-Ring Implantation

    LENUS (Irish Health Repository)

    Tanner, RE

    2018-05-01

    Failed surgical mitral valve repair using an annuloplasty ring has traditionally been treated with surgical valve replacement or repair1. For patients at high risk for repeat open heart surgery, placement of a trans-catheter aortic valve (i.e., TAVI valve) within the mitral ring (i.e., Mitral-Valve-in-Ring, MViR) has emerged as a novel alternative treatment strategy2-5 . We describe our experience of a failed mitral valve repair that was successfully treated with a TAVI valve delivered via the trans-septal approach, and summarise the data relating to this emerging treatment strategy.

  1. Valve leakage inspection testing and maintenance process

    International Nuclear Information System (INIS)

    Aikin, J.A.; Reinwald, J.W.; Kittmer, C.A.

    1991-01-01

    In valve maintenance, packing rings that prevent leakage along the valve stem must periodically be replaced, either during routine maintenance or to correct a leak or valve malfunction. Tools and procedures currently in use for valve packing removal and inspection are generally of limited value due to various access and application problems. A process has been developed by AECL Research that addresses these problems. The process, using incompressible fluid pressure, quickly and efficiently confirms the integrity of the valve backseat, extracts hard-to-remove valve packing sets, and verifies the leak tightness of the repacked valve

  2. Anatomic, histopathologic, and echocardiographic features in a dog with an atypical pulmonary valve stenosis with a fibrous band of tissue and a patent ductus arteriosus.

    Science.gov (United States)

    Yoon, Hakyoung; Kim, Jaehwan; Nahm, Sang-Soep; Eom, Kidong

    2017-07-11

    Congenital pulmonary valve stenosis and patent ductus arteriosus are common congenital heart defects in dogs. However, concurrence of atypical pulmonary valve stenosis and patent ductus arteriosus is uncommon. This report describes the anatomic, histopathologic, and echocardiographic features in a dog with concomitant pulmonary valve stenosis and patent ductus arteriosus with atypical pulmonary valve dysplasia that included a fibrous band of tissue. A 1.5-year-old intact female Chihuahua dog weighing 3.3 kg presented with a continuous grade VI cardiac murmur, poor exercise tolerance, and an intermittent cough. Echocardiography indicated pulmonary valve stenosis, a thickened dysplastic valve without annular hypoplasia, and a type IIA patent ductus arteriosus. The pulmonary valve was thick line-shaped in systole and dome-shaped towards the right ventricular outflow tract in diastole. The dog suffered a fatal cardiac arrest during an attempted balloon pulmonary valvuloplasty. Necropsy revealed pulmonary valve dysplasia, commissural fusion, and incomplete opening and closing of the pulmonary valve because of a fibrous band of tissue causing adhesion between the right ventricular outflow tract and the dysplastic intermediate cusp of the valve. A fibrous band of tissue between the right ventricular outflow track and the pulmonary valve should be considered as a cause of pulmonary valve stenosis. Pulmonary valve stenosis and patent ductus arteriosus can have conflicting effects on diastolic and systolic dysfunction, respectively. Therefore, beta-blockers should always be used carefully, particularly in patients with a heart defect where there is concern about left ventricular systolic function.

  3. Transcatheter, valve-in-valve transapical aortic and mitral valve implantation, in a high risk patient with aortic and mitral prosthetic valve stenoses

    Directory of Open Access Journals (Sweden)

    Harish Ramakrishna

    2015-01-01

    Full Text Available Transcatheter valve implantation continues to grow worldwide and has been used principally for the nonsurgical management of native aortic valvular disease-as a potentially less invasive method of valve replacement in high-risk and inoperable patients with severe aortic valve stenosis. Given the burden of valvular heart disease in the general population and the increasing numbers of patients who have had previous valve operations, we are now seeing a growing number of high-risk patients presenting with prosthetic valve stenosis, who are not potential surgical candidates. For this high-risk subset transcatheter valve delivery may be the only option. Here, we present an inoperable patient with severe, prosthetic valve aortic and mitral stenosis who was successfully treated with a trans catheter based approach, with a valve-in-valve implantation procedure of both aortic and mitral valves.

  4. Effects of pressure and temperature on gate valve unwedging

    International Nuclear Information System (INIS)

    Damerell, P.S.; Harrison, D.H.; Hayes, P.W.; Simons, J.W.; Walker, T.A.

    1996-01-01

    The stem thrust required to unwedge a gate valve is influenced by the pressure and temperature when the valve is closed and by the changes in these conditions between closure and opening. open-quotes Pressure lockingclose quotes and open-quotes thermal bindingclose quotes refer to situations where pressure and temperature effects cause the unwedging load to be much higher than normal. A model of these phenomena has been developed. Wedging (closure) is modeled as developing an open-quotes interferenceclose quotes between the disk and its seat rings in the valve. The effects of pressure and temperature are analyzed to determine the change in this disk-to-seat open-quotes interferenceclose quotes. Flexibilities, of the disk, body, stem and yoke strongly influence the unwedging thrust. Calculations and limited comparisons to data have been performed for a range of valve designs and scenarios. Pressure changes can increase the unwedging load when there is either a uniform pressure decrease, or a situation where the bonnet pressure exceeds the pressures in the adjacent piping. Temperature changes can increase the unwedging load when: (1) valve closure at elevated system temperature produces a delayed stem expansion, (2) a temperature increase after closure produces a bonnet pressure increase, or (3) a temperature change after closure produces an increase in the disk-to-seat open-quotes interferenceclose quotes or disk-to-seat friction

  5. Surgical outcomes in native valve infectious endocarditis: the experience of the Cardiovascular Surgery Department - Cluj-Napoca Heart Institute.

    Science.gov (United States)

    Molnar, Adrian; Muresan, Ioan; Trifan, Catalin; Pop, Dana; Sacui, Diana

    2015-01-01

    The introduction of Duke's criteria and the improvement of imaging methods has lead to an earlier and a more accurate diagnosis of infectious endocarditis (IE). The options for the best therapeutic approach and the timing of surgery are still a matter of debate and require a close colaboration between the cardiologist, the infectionist and the cardiac surgeon. We undertook a retrospective, descriptive study, spanning over a period of five years (from January 1st, 2007 to December 31st, 2012), on 100 patients who underwent surgery for native valve infectious endocarditis in our unit. The patients' age varied between 13 and 77 years (with a mean of 54 years), of which 85 were males (85%). The main microorganisms responsible for IE were: Streptococcus Spp. (21 cases - 21%), Staphylococcus Spp. (15 cases - 15%), and Enterococcus Spp. (9 cases - 9%). The potential source of infection was identified in 26 patients (26%), with most cases being in the dental area (16 cases - 16%). The lesions caused by IE were situated in the left heart in 96 patients (96%), mostly on the aortic valve (50 cases - 50%). In most cases (82%) we found preexisting endocardial lesions which predisposed to the development of IE, most of them being degenerative valvular lesions (38 cases - 38%). We performed the following surgical procedures: surgery on a single valve - aortic valve replacement (40 cases), mitral valve replacement (19 cases), mitral valve repair (1 case), surgery on more than one valve - mitral and aortic valve replacement (20 cases), aortic and tricuspid valve replacement (1 case), aortic valve replacement with a mechanical valve associated with mitral valve repair (5 cases), aortic valve replacement with a biological valve associated with mitral valve repair (2 cases), and mitral valve replacement with a mechanical valve combined with De Vega procedure on the tricuspid valve (1 case). In 5 patients (5%) the bacteriological examination of valve pieces excised during surgery was

  6. Surgical outcomes in native valve infectious endocarditis: the experience of the Cardiovascular Surgery Department – Cluj-Napoca Heart Institute

    Science.gov (United States)

    MOLNAR, ADRIAN; MURESAN, IOAN; TRIFAN, CATALIN; POP, DANA; SACUI, DIANA

    2015-01-01

    Background and aims The introduction of Duke’s criteria and the improvement of imaging methods has lead to an earlier and a more accurate diagnosis of infectious endocarditis (IE). The options for the best therapeutic approach and the timing of surgery are still a matter of debate and require a close colaboration between the cardiologist, the infectionist and the cardiac surgeon. Methods We undertook a retrospective, descriptive study, spanning over a period of five years (from January 1st, 2007 to December 31st, 2012), on 100 patients who underwent surgery for native valve infectious endocarditis in our unit. Results The patients’ age varied between 13 and 77 years (with a mean of 54 years), of which 85 were males (85%). The main microorganisms responsible for IE were: Streptococcus Spp. (21 cases – 21%), Staphylococcus Spp. (15 cases – 15%), and Enterococcus Spp. (9 cases – 9%). The potential source of infection was identified in 26 patients (26%), with most cases being in the dental area (16 cases – 16%). The lesions caused by IE were situated in the left heart in 96 patients (96%), mostly on the aortic valve (50 cases – 50%). In most cases (82%) we found preexisting endocardial lesions which predisposed to the development of IE, most of them being degenerative valvular lesions (38 cases – 38%). We performed the following surgical procedures: surgery on a single valve - aortic valve replacement (40 cases), mitral valve replacement (19 cases), mitral valve repair (1 case), surgery on more than one valve – mitral and aortic valve replacement (20 cases), aortic and tricuspid valve replacement (1 case), aortic valve replacement with a mechanical valve associated with mitral valve repair (5 cases), aortic valve replacement with a biological valve associated with mitral valve repair (2 cases), and mitral valve replacement with a mechanical valve combined with De Vega procedure on the tricuspid valve (1 case). In 5 patients (5%) the bacteriological

  7. Endoscopic Appearance of the Gastroesophageal Valve and Competence of the Cardia

    Directory of Open Access Journals (Sweden)

    T. Ismail

    1996-01-01

    Full Text Available The endoscopic appearance of the gastroesophageal valve, viewed by the retroflexed gastroscope, has been studied in 51 patients with and without reflux esophagitis. Esophagitis was graded according to its severity, and the yield pressure (YP was measured in all patients to assess the competence of the cardia. There was a close relationship between the YP and the grades of the gastroesophageal valve. YP was significantly lower in patients with endoscopic oesophagitis than in patients with no evidence of reflux esophagitis (p <0.0001. An increased abnormality of the gastroesophageal valve was associated with all grades of esophagitis and with a low YP. The valve mechanism at the cardia has an important role in determining its competence. YP is possibly a measure of the flap valve component of the gastroesophageal junction.

  8. The effect of valve strategy on in-cylinder flow and combustion

    Energy Technology Data Exchange (ETDEWEB)

    Soederberg, F

    1997-01-01

    This paper examines the effects of different valve strategies and their effect on in-cylinder flow and combustion. A conventional four valve per cylinder otto engine was modified to enable optical access. The flow measurements were made with a two-component laser Doppler velocimetry system. The combustion was monitored by running pressure data from a pressure transducer through a one-zone heat release model. The results show that when the valves operate normally a barrel flow is present and when one valve is closed a swirling flow occurs. No increase in turbulence was found with later phasing, except in the case of very late inlet valve opening and port deactivation. This resulted in a jet with high turbulence, making the combustion fast and stable, even with a very lean mixture ({lambda}=1.8). 6 refs, 44 figs, 4 tabs

  9. Preoperative planning with three-dimensional reconstruction of patient's anatomy, rapid prototyping and simulation for endoscopic mitral valve repair.

    Science.gov (United States)

    Sardari Nia, Peyman; Heuts, Samuel; Daemen, Jean; Luyten, Peter; Vainer, Jindrich; Hoorntje, Jan; Cheriex, Emile; Maessen, Jos

    2017-02-01

    Mitral valve repair performed by an experienced surgeon is superior to mitral valve replacement for degenerative mitral valve disease; however, many surgeons are still deterred from adapting this procedure because of a steep learning curve. Simulation-based training and planning could improve the surgical performance and reduce the learning curve. The aim of this study was to develop a patient-specific simulation for mitral valve repair and provide a proof of concept of personalized medicine in a patient prospectively planned for mitral valve surgery. A 65-year old male with severe symptomatic mitral valve regurgitation was referred to our mitral valve heart team. On the basis of three-dimensional (3D) transoesophageal echocardiography and computed tomography, 3D reconstructions of the patient's anatomy were constructed. By navigating through these reconstructions, the repair options and surgical access were chosen (minimally invasive repair). Using rapid prototyping and negative mould fabrication, we developed a process to cast a patient-specific mitral valve silicone replica for preoperative repair in a high-fidelity simulator. Mitral valve and negative mould were printed in systole to capture the pathology when the valve closes. A patient-specific mitral valve silicone replica was casted and mounted in the simulator. All repair techniques could be performed in the simulator to choose the best repair strategy. As the valve was printed in systole, no special testing other than adjusting the coaptation area was required. Subsequently, the patient was operated, mitral valve pathology was validated and repair was successfully done as in the simulation. The patient-specific simulation and planning could be applied for surgical training, starting the (minimally invasive) mitral valve repair programme, planning of complex cases and the evaluation of new interventional techniques. The personalized medicine could be a possible pathway towards enhancing reproducibility

  10. Options for Heart Valve Replacement

    Science.gov (United States)

    ... Guide: Understanding Your Heart Valve Problem | Spanish Symptom Tracker | Spanish Pre-surgery Checklist | Spanish What Is Heart ... Cardiac Arrest: How Are They Different? 7 Warning Signs of a Heart Attack 8 Low Blood Pressure - ...

  11. Minimally invasive aortic valve replacement

    DEFF Research Database (Denmark)

    Foghsgaard, Signe; Schmidt, Thomas Andersen; Kjaergard, Henrik K

    2009-01-01

    In this descriptive prospective study, we evaluate the outcomes of surgery in 98 patients who were scheduled to undergo minimally invasive aortic valve replacement. These patients were compared with a group of 50 patients who underwent scheduled aortic valve replacement through a full sternotomy...... operations were completed as mini-sternotomies, 4 died later of noncardiac causes. The aortic cross-clamp and perfusion times were significantly different across all groups (P replacement...... is an excellent operation in selected patients, but its true advantages over conventional aortic valve replacement (other than a smaller scar) await evaluation by means of randomized clinical trial. The "extended mini-aortic valve replacement" operation, on the other hand, is a risky procedure that should...

  12. Conceptual design of a quasi-homogeneous pressurized heavy water reactor to be operated in the closed Th-U233 fuel cycle

    International Nuclear Information System (INIS)

    1979-06-01

    This paper deals with the heavy water reactor, which, from the neutron economy point of view, offers advantages over the light water reactor. Its capability to be fuelled with natural uranium has also been considered a desirable nuclear option by various countries with sufficient domestic uranium resources not wishing to be dependent on the import of enrichment and other fuel cycle services which, in addition, would draw on the foreign exchange reserves. Pressurized heavy water reactors have been designed and built according to two somewhat different versions. While the Canadian CANDU-PHWR concept uses pressure tubes in a nearly unpressurized moderator tank (calandria), the German development line takes advantage of the established and well proven LWR technology, and, thus, uses a pressure vessel design where coolant channels and the surrounding moderator are held at equal pressure. This pressure vessel type heavy water reactor which has been built on a commercial demonstration plant level at ATUCHA in Argentina is described in a companion paper where also a conceptual design for a 685 MWsub(e) PHWR is discussed

  13. A nuclear radiation actuated valve for a nuclear reactor

    International Nuclear Information System (INIS)

    Christiansen, D.W.; Schively, D.P.

    1983-01-01

    The valve has a first part (such as a valve rod with piston) and a second part (such as a valve tube surrounding the valve rod, with the valve tube having side slots surrounding the piston). Both valve parts have known nuclear radiation swelling characteristics which are different. The valve parts are positioned so that the valve's first and second parts create a valve orifice which changes in size due to the different nuclear radiation caused swelling of the valve's first part compared to the valve's second part. The valve may be used in a nuclear reactor's core coolant system. (author)

  14. Development of closed cycle infrastructure at VNIPIET

    International Nuclear Information System (INIS)

    Onufrienko, S.V.; Kuzin, A.S.; Shafrova, N.P.; Zavadskij, M.I.

    2012-01-01

    Background to the creation of a closed nuclear fuel cycle is described. Achievements and future development projects of the Leading Institute VNIPIET are listed. The diagram of the closed nuclear fuel cycle in Russia with separate uranium and plutonium recycling is given. The major milestones of the VNIPIET history are reported [ru

  15. Automatically closing swing gate closure assembly

    Science.gov (United States)

    Chang, Shih-Chih; Schuck, William J.; Gilmore, Richard F.

    1988-01-01

    A swing gate closure assembly for nuclear reactor tipoff assembly wherein the swing gate is cammed open by a fuel element or spacer but is reliably closed at a desired closing rate primarily by hydraulic forces in the absence of a fuel charge.

  16. Improved drying rate diagnostics for saturated fuel debris at the INEEL

    International Nuclear Information System (INIS)

    Childs, K.; Christensen, A.

    1999-01-01

    A fuel canning station (FCS) has been operated for ∼2 yr to prepare for the dry storage of a variety of spent reactor fuels stored in pools at the Idaho National Engineering and Environmental Laboratory (INEEL). The FCS dewaters the fuel and then passivates possibly pyrophoric components in the fuel. Fuel-loaded canisters are placed into a heated insert, the canister is connected to a vacuum system, and the fuel is heated under a vacuum to remove the water. The dewatering system must also verify that the water was removed. The dryness criteria state that the canister pressure shall not exceed a defined pressure for a specified isolation time. Dewatering did not work well for defected TRIGA elements that had corroded in pool storage, leaving the intact fuel meat mixed with a bed of fines from metal oxides and from sludge that continuously accumulated within the pool. Dewatering these cans proved to be very time consuming. Fueled canisters were heated to 60 C and evacuated between 5 and 10 torr. At these conditions, intact fuels were rapidly dried (<10 h). TRIGA drying periods extended to 9 days. Dryness was qualitatively monitored using the canister pressure-control valve position. The valve closes as the gas flow rate declines, providing an indication that drying is complete. However, the valve remained open when drying TRIGA fuel, leaving no indication of dryness. In addition, dryness could not be verified because the canister pressure exceeded the defined pressure during isolation. Air leakage into the evacuated canister prevented the dryness from being verified. Air in-leakage and water vapor cannot easily be discriminated by the aforementioned procedures. Because the canister design does not seal above atmospheric pressure, a drying temperature that yielded a vapor pressure less than atmospheric pressure was chosen. A sufficiently long isolation test could then determine if air was accumulating in the canister; however, the low temperature reduced the drying

  17. Use of Main Loop Isolating Valves (GZZS) in WWER 440

    International Nuclear Information System (INIS)

    Stefanova, A.E.; Gencheva, R.V.; Groudev, P.P.

    2002-01-01

    This paper discusses the usage of Main Loop Isolation Valves in case of Steam Generator Tube Rupture accident in WWER440/V230. A double-ended single pipe break in SG-6 was chosen as representative. In the paper are investigated two cases. In the first one the operator isolates the affected loop by Main Loop Isolation Valves closing and after primary depressurization re-opens them to cooldown the damaged Steam Generator. The second case treats the situation, where Main Loop Isolation Valves fail to close with the necessary operator actions for managing plant recovery. RELAP5/MOD3.2 computer code has been used to simulate the Steam Generator Tube Rupture accident in WWER440 NPP model. This model was developed and validated at Institute for Nuclear Research and Nuclear Energy - Bulgarian Academy of Sciences. The results of analyses presented in this report demonstrate that in the both cases (with or without Main Loop Isolation Valves usage) the operator could bring the plant to stable and safety conditions (Authors)

  18. Effects on fatigue life of gate valves due to higher torque switch settings during operability testing

    International Nuclear Information System (INIS)

    Richins, W.D.; Snow, S.D.; Miller, G.K.; Russell, M.J.; Ware, A.G.

    1995-12-01

    Some motor operated valves now have higher torque switch settings due to regulatory requirements to ensure valve operability with appropriate margins at design basis conditions. Verifying operability with these settings imposes higher stem loads during periodic inservice testing. These higher test loads increase stresses in the various valve internal parts which may in turn increase the fatigue usage factors. This increased fatigue is judged to be a concern primarily in the valve disks, seats, yokes, stems, and stem nuts. Although the motor operators may also have significantly increased loading, they are being evaluated by the manufacturers and are beyond the scope of this study. Two gate valves representative of both relatively weak and strong valves commonly used in commercial nuclear applications were selected for fatigue analyses. Detailed dimensional and test data were available for both valves from previous studies at the Idaho National Engineering Laboratory. Finite element models were developed to estimate maximum stresses in the internal parts of the valves and to identity the critical areas within the valves where fatigue may be a concern. Loads were estimated using industry standard equations for calculating torque switch settings prior and subsequent to the testing requirements of USNRC Generic Letter 89--10. Test data were used to determine both; (1) the overshoot load between torque switch trip and final seating of the disk during valve closing and (2) the stem thrust required to open the valves. The ranges of peak stresses thus determined were then used to estimate the increase in the fatigue usage factors due to the higher stem thrust loads. The usages that would be accumulated by 100 base cycles plus one or eight test cycles per year over 40 and 60 years of operation were calculated

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

    International Nuclear Information System (INIS)

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

    1990-01-01

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

  20. Engine control system having fuel-based adjustment

    Science.gov (United States)

    Willi, Martin L [Dunlap, IL; Fiveland, Scott B [Metamora, IL; Montgomery, David T [Edelstein, IL; Gong, Weidong [Dunlap, IL

    2011-03-15

    A control system for an engine having a cylinder is disclosed having an engine valve configured to affect a fluid flow of the cylinder, an actuator configured to move the engine valve, and an in-cylinder sensor configured to generate a signal indicative of a characteristic of fuel entering the cylinder. The control system also has a controller in communication with the actuator and the sensor. The controller is configured to determine the characteristic of the fuel based on the signal and selectively regulate the actuator to adjust a timing of the engine valve based on the characteristic of the fuel.

  1. An experimental study of fuel injection strategies in CAI gasoline engine

    Energy Technology Data Exchange (ETDEWEB)

    Hunicz, J.; Kordos, P. [Department of Combustion Engines and Transport, Lublin University of Technology, Nadbystrzycka 36, 20-618 Lublin (Poland)

    2011-01-15

    Combustion of gasoline in a direct injection controlled auto-ignition (CAI) single-cylinder research engine was studied. CAI operation was achieved with the use of the negative valve overlap (NVO) technique and internal exhaust gas re-circulation (EGR). Experiments were performed at single injection and split injection, where some amount of fuel was injected close to top dead centre (TDC) during NVO interval, and the second injection was applied with variable timing. Additionally, combustion at variable fuel-rail pressure was examined. Investigation showed that at fuel injection into recompressed exhaust fuel reforming took place. This process was identified via an analysis of the exhaust-fuel mixture composition after NVO interval. It was found that at single fuel injection in NVO phase, its advance determined the heat release rate and auto-ignition timing, and had a strong influence on NO{sub X} emission. However, a delay of single injection to intake stroke resulted in deterioration of cycle-to-cycle variability. Application of split injection showed benefits of this strategy versus single injection. Examinations of different fuel mass split ratios and variable second injection timing resulted in further optimisation of mixture formation. At equal share of the fuel mass injected in the first injection during NVO and in the second injection at the beginning of compression, the lowest emission level and cyclic variability improvement were observed. (author)

  2. Numerical model and investigations of the externally heated valve Joule engine

    Energy Technology Data Exchange (ETDEWEB)

    Wojewoda, Jerzy [University of Aberdeen, School of Engineering, Fraser Noble Bldg, Aberdeen AB24 3UE (United Kingdom); Kazimierski, Zbyszko [Technical University of Lodz, Institute of Turbomachinery, 219/223 Wolczanska Str., 93-005 Lodz (Poland)

    2010-05-15

    The mineral fuels used recently, i.e., oil and gas, will be soon exploited out. This paper presents an idea of the engine where any fuel or solar heat can be used as a source of energy. The proposed model is an externally heated, 2-stroke, valve engine (EHVE). This is a piston-type engine, entirely different from the well-known Stirling one, which is the best known example of such a solution. It works in a closed Joule cycle and is designed to produce a moderate amount of energy. The engine is composed of typical parts met in piston designs: an expander, a compressor, a heater, a cooler and, additionally, two recirculation blowers, which consume a small amount of produced power. An additional advantage is its working medium, which may be simply atmospheric air and the engine has a conventional crankshaft and an oil lubrication system. It has already been proven that operation of the EHVE is possible with satisfactory power and efficiency at the output. Comparisons of the EHVE action with and without recirculation blowers are performed. (author)

  3. Experimental study on the effect of an artificial cardiac valve on the left ventricular flow

    Science.gov (United States)

    Wang, JiangSheng; Gao, Qi; Wei, RunJie; Wang, JinJun

    2017-09-01

    The use of artificial valves to replace diseased human heart valves is currently the main solution to address the malfunctioning of these valves. However, the effect of artificial valves on the ventricular flow still needs to be understood in flow physics. The left ventricular flow downstream of a St. Jude Medical (SJM) bileaflet mechanical heart valve (BMHV), which is a widely implanted mechanical bileaflet valve, is investigated with time-resolved particle image velocimetry in the current work. A tilting-disk valve is installed on the aortic orifice to guarantee unidirectional flow. Several post-processing tools are applied to provide combined analyses of the physics involved in the ventricular flow. The triple jet pattern that is closely related to the characteristics of the bileaflet valve is discussed in detail from both Eulerian and Lagrangian views. The effects of large-scale vortices on the transportation of blood are revealed by the combined analysis of the tracking of Lagrangian coherent structures, the Eulerian monitoring of the shear stresses, and virtual dye visualization. It is found that the utilization of the SJM BMHV complicates the ventricular flow and could reduce the efficiency of blood transportation. In addition, the kinematics of the bileaflets is presented to explore the effects of flow structures on their motion. These combined analyses could elucidate the properties of SJM BMHV. Furthermore, they could provide new insights into the understanding of other complex blood flows.

  4. Numerical analysis and experimental studies on solenoid common rail diesel injector with worn control valve

    Science.gov (United States)

    Krivtsov, S. N.; Yakimov, I. V.; Ozornin, S. P.

    2018-03-01

    A mathematical model of a solenoid common rail fuel injector was developed. Its difference from existing models is control valve wear simulation. A common rail injector of 0445110376 Series (Cummins ISf 2.8 Diesel engine) produced by Bosch Company was used as a research object. Injector parameters (fuel delivery and back leakage) were determined by calculation and experimental methods. GT-Suite model average R2 is 0.93 which means that it predicts the injection rate shape very accurately (nominal and marginal technical conditions of an injector). Numerical analysis and experimental studies showed that control valve wear increases back leakage and fuel delivery (especially at 160 MPa). The regression models for determining fuel delivery and back leakage effects on fuel pressure and energizing time were developed (for nominal and marginal technical conditions).

  5. Small sodium valve design and operating experience

    International Nuclear Information System (INIS)

    Abramson, R.; Elie, X.; Vercasson, M.; Nedelec, J.

    1974-01-01

    Conventionally, valves for sodium pipes smaller than 125 mm in diameter are called ''small sodium valves''. However, this limit should rather be considered as the lower limit o ''large sodium valves''. In fact, both the largest sizes of small valves and the smallest of large valves can be found in the range of 125-300 mm in diameter. Thus what is said about small valves also applies, for a few valve types, above the 125 mm limit. Sodium valves are described here in a general manner, with no manufacturing details except when necessary for understanding valve behavior. Operating experience is pointed out wherever possible. Finally, some information is given about ongoing or proposed development plans. (U.S.)

  6. Design of the Modular Pneumatic Valve Terminal

    Directory of Open Access Journals (Sweden)

    Jakub E. TAKOSOGLU

    2015-11-01

    Full Text Available The paper presents design of the modular pneumatic valve terminal, which was made on the basis of the patent application No A1 402905 „A valve for controlling fluid power drives, specially for pneumatic actuators, and the control system for fluid power drives valves”. The authors describe a method of operation of the system with double-acting valve and 5/2 (five ways and two position valve. Functions of the valve, and an example of application of the valve terminal in the production process were presented. 3D solid models of all the components of the valve were made. The paper presents a complete 3D model of the valve in various configurations. Using CAD-embedded SOLIDWORKS Flow Simulation computational fluid dynamics CFD analysis was also carried out of compressed air flow in the ways of the valve elements

  7. Numerical Predictions of Flow Characteristics in a 90 Degree Bended Upward Elbow Located at the Downstream Region of a Flow Control Valve (Butterfly Valve)

    International Nuclear Information System (INIS)

    Won, Se Youl; Park, Young Sheop; Kim, Yun Jung; Oh, Seung Jong

    2006-01-01

    Butterfly valves are widely used in industrial piping components. They are used for flow control in large diameter pipes because of their lightweight, simple structure and the rapidity of manipulation. Any flow disturbing components such as elbows, orifice plates and tees are recommended to be located in a distance of 8 diameters (L/D.8) from the downstream of butterfly valves to decrease the effect of flow disturbance. However, one would encounter cases where other piping components are installed in a close proximity due to the space restriction. In these cases, the numerical simulation will be useful to evaluate the impact of flow disturbances. In this study, we have examined one practical case encountered where the elbow is located in a close proximity to the butterfly valve. Due to the close proximity, we are concerned about pipe thinning and we use the numerical evaluation to determine the range of operating regime and options

  8. HDR-investigations of check valve closure and resultant water hammer effects

    International Nuclear Information System (INIS)

    Scholl, K.D.

    1983-01-01

    The presented investigations are based on the Loss of Coolant Accident (LOCA). They concentrate on the first blowdown phase after pipe break of a feedwater line. The effect of such a break is moderated by quick closing check valves, by which the loss of coolant water is reduced and optimal post accident conditions are obtained. Unfortunately the closure of the valve can cause high pressure peaks (water hammer effects) in the feedwater system which potentially could produce safety relevant secondary damage. The system loading by these effects has been analysed. The HDR-Investigation-results led to an improvement of the feedwater system safety by verifying damping measures of quick closing check valves. Pressure peaks obtained with undamped valves in the range of 300 bars, are reduced to zero or a few bars above the normal operation pressure in feedwater systems. For the analytical simulation of valve closure the following dominant acting forces are identified: the blowdown flow resistance of the valve cone and the damping pistong force. The analytical description and quantification of the forces depends on blowdown flow and valve friction parameters. These have been evaluated and are presented for practical use. (orig.)

  9. Development of an effective valve packing program

    Energy Technology Data Exchange (ETDEWEB)

    Hart, K.A.

    1996-12-01

    Current data now shows that graphite valve packing installed within the guidance of a controlled program produces not only reliable stem sealing but predictable running loads. By utilizing recent technological developments in valve performance monitoring for both MOV`s and AOV`s, valve packing performance can be enhanced while reducing maintenance costs. Once known, values are established for acceptable valve packing loads, the measurement of actual valve running loads via the current MOV/AOV diagnostic techniques can provide indication of future valve stem sealing problems, improper valve packing installation or identify the opportunity for valve packing program improvements. At times the full benefit of these advances in material and predictive technology remain under utilized due to simple past misconceptions associated with valve packing. This paper will explore the basis for these misconceptions, provide general insight into the current understanding of valve packing and demonstrate how with this new understanding and current valve diagnostic equipment the key aspects required to develop an effective, quality valve packing program fit together. The cost and operational benefits provided by this approach can be significant impact by the: elimination of periodic valve repacking, reduction of maintenance costs, benefits of leak-free valve operation, justification for reduced Post Maintenance Test Requirements, reduced radiation exposure, improved plant appearance.

  10. Risk assessment of K basin twelve-inch drain valve failure from a postulated seismic initiating event

    International Nuclear Information System (INIS)

    MORGAN, R.G.

    1999-01-01

    The Spent Nuclear Fuel (SNF) Project will transfer metallic SNF from the Hanford 105 K-East and 105 K-West Basins to safe interim storage in the Canister Storage Building in the 200 Area. The initial basis for design, fabrication, installation, and operation of the fuel removal systems was that the basin leak rates which could result from a postulated accident condition would not be excessive relative to reasonable recovery operations. However, an additional potential K Basin water leak path is through the K Basin drain valves. Three twelve-inch drain valves are located in the main basin bays along the north wall. The sumps containing the valves are filled with concrete which covers the drain valve body. Visual observations suggest that only the valve's bonnet and stem are exposed above the basin concrete floor. It was recognized, however, that damage of the drain valve bonnet or stem during a seismic initiating event could provide a potential K Basin water leak path. The objectives of this activity are to: (1) evaluate the risk of damaging the three twelve-inch drain valves located along the north wall of the main basin from a seismic initiating event, and (2) determine the associated potential leak rate from a damaged valve

  11. Risk assessment of K basin twelve-inch drain valve failure from a postulated seismic initiating event

    Energy Technology Data Exchange (ETDEWEB)

    MORGAN, R.G.

    1999-04-06

    The Spent Nuclear Fuel (SNF) Project will transfer metallic SNF from the Hanford 105 K-East and 105 K-West Basins to safe interim storage in the Canister Storage Building in the 200 Area. The initial basis for design, fabrication, installation, and operation of the fuel removal systems was that the basin leak rates which could result from a postulated accident condition would not be excessive relative to reasonable recovery operations. However, an additional potential K Basin water leak path is through the K Basin drain valves. Three twelve-inch drain valves are located in the main basin bays along the north wall. The sumps containing the valves are filled with concrete which covers the drain valve body. Visual observations suggest that only the valve's bonnet and stem are exposed above the basin concrete floor. It was recognized, however, that damage of the drain valve bonnet or stem during a seismic initiating event could provide a potential K Basin water leak path. The objectives of this activity are to: (1) evaluate the risk of damaging the three twelve-inch drain valves located along the north wall of the main basin from a seismic initiating event, and (2) determine the associated potential leak rate from a damaged valve.

  12. Soft valves in plants

    Science.gov (United States)

    Park, Keunhwan; Tixier, Aude; Christensen, Anneline; Arnbjerg-Nielsen, Sif; Zwieniecki, Maciej; Jensen, Kaare

    2017-11-01

    Water and minerals flow from plant roots to leaves in the xylem, an interconnected network of vascular conduits that spans the full length of the organism. When a plant is subjected to drought stress, air pockets can spread inside the xylem, threatening the survival of the plant. Many plants prevent propagation of air by using hydrophobic nano-membranes in the ``pit'' pores that link adjacent xylem cells. This adds considerable resistance to flow. Interestingly, torus-margo pit pores in conifers are open and offer less resistance. To prevent propagation of air, conifers use a soft gating mechanism, which relies on hydrodynamic interactions between the xylem liquid and the elastic pit. However, it is unknown exactly how it is able to combine the seemingly antagonist functions of high permeability and resistance to propagation of air. We conduct experiments on biomimetic pores to elucidate the flow regulation mechanism. The design of plant valves is compared to other natural systems and optimal strategies are discussed. This work was supported by a research Grant (13166) from VILLUM FONDEN.

  13. Annular flow diverter valve

    International Nuclear Information System (INIS)

    Rider, R.L.

    1980-01-01

    A valve is described for diverting flow from the center of two concentric tubes to the annulus between the tubes or, operating in the reverse direction, for mixing fluids from concentric tubes into a common tube and for controlling the volume ratio of said flow. It consists of a toroidal baffle disposed in sliding engagement with the interior of the inner tube downstream of a plurality of ports in the inner tube, a plurality of gates in sliding engagement with the interior of the inner tube attached to the baffle for movement therewith, a servomotor having a bullet-shaped plug on the downstream end thereof, and drive rods connecting the servomotor to the toroidal baffle. The sevomotor is adapted to move the baffle into mating engagement with the bullet-shaped plug and simultaneously move the gates away from the ports in the inner tube and to move the baffle away from the bullet-shaped plug and simultaneously move the gates to cover the ports in the inner tube

  14. Fuel assembly

    International Nuclear Information System (INIS)

    Hirukawa, Koji; Sakurada, Koichi.

    1992-01-01

    In a fuel assembly for a BWR type reactor, water rods or water crosses are disposed between fuel rods, and a value with a spring is disposed at the top of the coolant flow channel thereof, which opens a discharge port when pressure is increased to greater than a predetermined value. Further, a control element for the amount of coolant flow rate is inserted retractable to a control element guide tube formed at the lower portion of the water rod or the water cross. When the amount of control elements inserted to the control element guide tube is small and the inflown coolant flow rate is great, the void coefficient at the inside of the water rod is less than 5%. On the other hand, when the control elements are inserted, the flow resistance is increased, so that the void coefficient in the water rod is greater than 80%. When the pressure in the water rod is increased, the valve with the spring is raised to escape water or steams. Then, since the variation range of the change of the void coefficient can be controlled reliably by the amount of the control elements inserted, and nuclear fuel materials can be utilized effectively. (N.H.)

  15. Optimization of geometry of annular seat valves suitable for Digital Displacement fluid power pumps/motors

    DEFF Research Database (Denmark)

    Rømer, Daniel; Johansen, Per; Pedersen, Henrik C.

    2013-01-01

    Digital Displacement Fluid Power is an upcoming technology setting new standards for the achievable efficiency of fluid power pumps and motors. The core element of the Digital Displacement technology is high performance electronically controlled seat valves, which must exhibit very low flow...... work an annular seat valve suitable for use in Digital Displacement units is considered, and the ring geometry is optimized using finite element analysis including non-linear material behaviour, contact elements and fluid pressure penetrating load, closely reflecting the actual load of the seat valve...

  16. Reliability analysis of a hydraulic on/off fast switching valve

    DEFF Research Database (Denmark)

    Bender, Niels Christian; Pedersen, Henrik Clemmensen; Plöckinger, Andreas

    2017-01-01

    allowed internal leakage across the valve seat (0.0005 and 0.5 L/min). The study shows that the probability of a low leakage failure is close to 100% before 5 years of operation and 10% risk of high leakage failure after 25 years of operation. Valve seat failure is therefore a potential threat to limit....... Specifically, the mechanical topology of Fast Switching hydraulic Valves (FSVs) are of interest since these undergo operating cycles in the gigacycle regime in theirs functional lifetime. Application of these FSVs is relevant in e.g. digital displacement units, which for the specific design considered...

  17. Bioprosthetic Valve Fracture During Valve-in-valve TAVR: Bench to Bedside.

    Science.gov (United States)

    Saxon, John T; Allen, Keith B; Cohen, David J; Chhatriwalla, Adnan K

    2018-01-01

    Valve-in-valve (VIV) transcatheter aortic valve replacement (TAVR) has been established as a safe and effective means of treating failed surgical bioprosthetic valves (BPVs) in patients at high risk for complications related to reoperation. Patients who undergo VIV TAVR are at risk of patient-prosthesis mismatch, as the transcatheter heart valve (THV) is implanted within the ring of the existing BPV, limiting full expansion and reducing the maximum achievable effective orifice area of the THV. Importantly, patient-prosthesis mismatch and high residual transvalvular gradients are associated with reduced survival following VIV TAVR. Bioprosthetic valve fracture (BVF) is as a novel technique to address this problem. During BPV, a non-compliant valvuloplasty balloon is positioned within the BPV frame, and a highpressure balloon inflation is performed to fracture the surgical sewing ring of the BPV. This allows for further expansion of the BPV as well as the implanted THV, thus increasing the maximum effective orifice area that can be achieved after VIV TAVR. This review focuses on the current evidence base for BVF to facilitate VIV TAVR, including initial bench testing, procedural technique, clinical experience and future directions.

  18. Reconnection of SN-216 to U-D Valve Pit Design Review

    International Nuclear Information System (INIS)

    REED, R.W.

    1999-01-01

    The design for the reconnection of SN-216 to U-D valve pit was reviewed on May 24, 1999. All Review Comment Record comments were resolved and closed at this meeting. The review concluded that the reconnection of SN-216 to U-D valve pit was acceptable. The design was approved with the incorporated comments as recorded on the RCR's. No outstanding comments remain

  19. Worcester 1 Inch Solenoid-Actuated Gas Operated SCHe System Valves

    International Nuclear Information System (INIS)

    VAN KATWIJK, C.

    2000-01-01

    1 inch Gas-operated full-port ball valves incorporate a solenoid and limit switches as integral parts of the actuator. These valves are normally open and fail safe to the open position (GOV-1*02 and 1*06 fail closed) to provide a flow path of helium gas to the MCO under helium purge and off-normal conditions when the MCO is isolated

  20. Closed cycle gas dynamic laser

    International Nuclear Information System (INIS)

    Pinsley, E.A.

    1975-01-01

    The device includes a closed cycle gasdynamic laser wherein the lasing fluid is recirculated in a closed loop. The closed loop includes a nozzle array, a lasing cavity and a diffuser. The exit of the diffuser is connected to the inlet to the nozzle array with a fuel heat exchanger located in the lasing flow and a pumping means located between the heat exchanger and the nozzle array. To provide for cooling of the pumping means and to improve diffuser performance, gas bled from the diffuser is cooled by two heat exchangers and pumped into cooling passages in the pumping means. The heat exchangers for cooling the flow to the pumping means are located in series and carry fuel from a supply to an injector in said combustor and the heat exchanger in the lasing flow cools the fluid and carries the fuel from a supply to an injector in said combustor. (U.S.)

  1. LOFT pressurizer safety: relief valve reliability

    International Nuclear Information System (INIS)

    Brown, E.S.

    1978-01-01

    The LOFT pressurizer self-actuating safety-relief valves are constructed to the present state-of-the-art and should have reliability equivalent to the valves in use on PWR plants in the U.S. There have been no NRC incident reports on valve failures to lift that would challenge the Technical Specification Safety Limit. Fourteen valves have been reported as lifting a few percentage points outside the +-1% Tech. Spec. surveillance tolerance (9 valves tested over and 5 valves tested under specification). There have been no incident reports on failures to reseat. The LOFT surveillance program for assuring reliability is equivalent to nuclear industry practice

  2. Valve system incorporating single failure protection logic

    Science.gov (United States)

    Ryan, Rodger; Timmerman, Walter J. H.

    1980-01-01

    A valve system incorporating single failure protective logic. The system consists of a valve combination or composite valve which allows actuation or de-actuation of a device such as a hydraulic cylinder or other mechanism, integral with or separate from the valve assembly, by means of three independent input signals combined in a function commonly known as two-out-of-three logic. Using the input signals as independent and redundant actuation/de-actuation signals, a single signal failure, or failure of the corresponding valve or valve set, will neither prevent the desired action, nor cause the undesired action of the mechanism.

  3. LOFT pressurizer safety: relief valve reliability

    Energy Technology Data Exchange (ETDEWEB)

    Brown, E.S.

    1978-01-18

    The LOFT pressurizer self-actuating safety-relief valves are constructed to the present state-of-the-art and should have reliability equivalent to the valves in use on PWR plants in the U.S. There have been no NRC incident reports on valve failures to lift that would challenge the Technical Specification Safety Limit. Fourteen valves have been reported as lifting a few percentage points outside the +-1% Tech. Spec. surveillance tolerance (9 valves tested over and 5 valves tested under specification). There have been no incident reports on failures to reseat. The LOFT surveillance program for assuring reliability is equivalent to nuclear industry practice.

  4. Anterior urethral valves: not such a benign condition…

    Directory of Open Access Journals (Sweden)

    Omar eCruz-Diaz

    2013-11-01

    Full Text Available Purpose: Anterior urethral valves (AUV is an unusual cause of congenital obstruction of the male urethra, being 15 to 30 times less common than posterior urethral valves (PUV. It has been suggested that patients with congenital anterior urethral obstruction have a better prognosis than those with PUV.The long term prognosis of anterior urethral valves is not clear in the literature. In this report we describe our experience and long-term follow up of patients with AUV.Materials and methods: We retrospectively identified 13 patients who presented with the diagnosis of AUV in our institutions between 1994 and 2012. From the 11 patients included, we evaluated the gestational age, ultrasound and voiding cystourethrogram findings, age upon valve ablation, micturition pattern, creatinine and clinical follow up.Results: Between 1994 and 2012 we evaluated 150 patients with the diagnosis of urethral valves, where 11 patients (7.3% had AUV and an adequate follow up. Mean follow up is 6.3 years. 5 patients (45.4% had pre-natal diagnosis of AUV. The most common prenatal ultrasonographic finding was bilateral hydronephrosis and distended bladder.The mean gestational age was 37.6 weeks. Postnatally, 90% had trabeculated bladder, 80% hydronephrosis and 40% renal dysplasia. The most common clinical presentation was urinary tract infection in 5 patients (45.4%.7 patients (63.6% had primary transurethral valve resection or laser ablation and 3 patients (27.2% had primary vesicostomies. One boy (9.1% had urethrostomy with urethral diverticulum excision. 2 patients (18.2% developed end-stage renal disease (ESRD.Conclusions: Early urinary tract obstruction resulted in ESRD in 18% of our patient population. In our series, the complication rate and the evolution to renal failure are high and similar to patients with PUV. In patients with AUV we recommend long-term follow up and close evaluation of patient’s bladder and renal function.

  5. The effect of varying degrees of stenosis on the characteristics of turbulent pulsatile flow through heart valves.

    Science.gov (United States)

    Bluestein, D; Einav, S

    1995-08-01

    Many problems and complications associated with heart valves are related to the dynamic behavior of the valve and the resultant unsteady flow patterns. An accurate depiction of the spatial and temporal velocity and rms distributions imparts better understanding of flow related valve complications, and may be used as a guideline in valve design. While the generalized correlation between increased turbulence level and the severity of the stenosis is well established, few studies addressed the issue of the intermittent nature of turbulence and its timing in the cardiac cycle, and almost none assessed the effect of a progressive stenosis on the flow characteristics through heart valves. In this experimental work we simulated the type of flow which is present in normal and stenosed valves and conducted a comprehensive investigation of valve hemodynamics, valvular turbulence and morphology under varying degrees of stenosis. The characteristics of valves and stenoses were simulated closely, to achieve the flow conditions that initiate turbulent flow conditions. Laser Doppler anemometry (LDA) measurements were carried out in a pulse duplicator system distal to trileaflet polyurethane prosthetic heart valves, installed at mitral and aortic positions. The effect of the degree of the stenosis was comparatively studied through the structure of the turbulent jets emerging from normal and stenotic heart valves. Maximum turbulence level was achieved during the decelerating phase and correlated to the severity of the stenosis, followed by relaminarization of the flow during the acceleration phase. The intermittent nature of the turbulence emphasized the importance of realizing the timing of the turbulence production and its spatial location for optimizing current valve designs. The plug flow through the normal aortic valve prosthesis was replaced by jet like behavior for a 65% stenosis, with the jet becoming narrower and stronger for a 90% stenosis. The morphology of the velocity

  6. Stem thrust prediction model for W-K-M double wedge parallel expanding gate valves

    Energy Technology Data Exchange (ETDEWEB)

    Eldiwany, B.; Alvarez, P.D. [Kalsi Engineering Inc., Sugar Land, TX (United States); Wolfe, K. [Electric Power Research Institute, Palo Alto, CA (United States)

    1996-12-01

    An analytical model for determining the required valve stem thrust during opening and closing strokes of W-K-M parallel expanding gate valves was developed as part of the EPRI Motor-Operated Valve Performance Prediction Methodology (EPRI MOV PPM) Program. The model was validated against measured stem thrust data obtained from in-situ testing of three W-K-M valves. Model predictions show favorable, bounding agreement with the measured data for valves with Stellite 6 hardfacing on the disks and seat rings for water flow in the preferred flow direction (gate downstream). The maximum required thrust to open and to close the valve (excluding wedging and unwedging forces) occurs at a slightly open position and not at the fully closed position. In the nonpreferred flow direction, the model shows that premature wedging can occur during {Delta}P closure strokes even when the coefficients of friction at different sliding surfaces are within the typical range. This paper summarizes the model description and comparison against test data.

  7. Stem thrust prediction model for W-K-M double wedge parallel expanding gate valves

    International Nuclear Information System (INIS)

    Eldiwany, B.; Alvarez, P.D.; Wolfe, K.

    1996-01-01

    An analytical model for determining the required valve stem thrust during opening and closing strokes of W-K-M parallel expanding gate valves was developed as part of the EPRI Motor-Operated Valve Performance Prediction Methodology (EPRI MOV PPM) Program. The model was validated against measured stem thrust data obtained from in-situ testing of three W-K-M valves. Model predictions show favorable, bounding agreement with the measured data for valves with Stellite 6 hardfacing on the disks and seat rings for water flow in the preferred flow direction (gate downstream). The maximum required thrust to open and to close the valve (excluding wedging and unwedging forces) occurs at a slightly open position and not at the fully closed position. In the nonpreferred flow direction, the model shows that premature wedging can occur during ΔP closure strokes even when the coefficients of friction at different sliding surfaces are within the typical range. This paper summarizes the model description and comparison against test data

  8. 46 CFR 56.50-75 - Diesel fuel systems.

    Science.gov (United States)

    2010-10-01

    ... with controls to comply with § 58.01-25 of this subchapter. (2) The installation shall comply with § 56... and drains. Valves for removing water or impurities from fuel oil systems will be permitted in the machinery space provided such valves are fitted with caps or plugs to prevent leakage. (6) Filling pipe...

  9. Wedge gate valves selecting essentials in pipeline systems designing based on permissible operation parameters

    Science.gov (United States)

    Zakirnichnaya, M. M.; Kulsharipov, I. M.

    2017-10-01

    Wedge gate valves are widely used at the fuel and energy complex enterprises. The pipeline valves manufacturers indicate the safe operation resource according to the current regulatory and technical documentation. In this case, the resource value of the valve body strength calculation results is taken into consideration as the main structural part. However, it was determined that the wedge gate valves fail before the assigned resource due to the occurrence of conditions under which the wedge breaks in the hooks and, accordingly, the sealing integrity is not ensured. In this regard, it became necessary to assess the conditions under which the resource should be assigned not only to the valve body, but also to take into account the wedge durability. For this purpose, wedge resource calculations were made using the example of ZKL2 250-25 and ZKL2 300-25 valves using the ABAQUS software package FE-SAFE module under the technological parameters influence on the basis of their stressstrain state calculation results. Operating conditions, under which the wedge resource value is lower than the one set by the manufacturer, were determined. A technique for limiting the operating parameters for ensuring the wedge durability during the wedge gate valve assigned resource is proposed.

  10. Development of the novel control algorithm for the small proton exchange membrane fuel cell stack without external humidification

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tae-Hoon; Kim, Sang-Hyun; Kim, Wook; Lee, Jong-Hak; Cho, Kwan-Seok; Choi, Woojin [Department of Electrical Engineering, Soongsil University, 1-1 Sangdo-dong, Dongjak-gu, Seoul 156-743 (Korea); Park, Kyung-Won [Department of Chemical/Environmental Engineering, Soongsil University, 1-1 Sangdo-dong, Dongjak-gu, Seoul 156-743 (Korea)

    2010-09-15

    Small PEM (proton exchange membrane) fuel cell systems do not require humidification and have great commercialization possibilities. However, methods for controlling small PEM fuel cell stacks have not been clearly established. In this paper, a control method for small PEM fuel cell systems using a dual closed loop with a static feed-forward structure is defined and realized using a microcontroller. The fundamental elements that need to be controlled in fuel cell systems include the supply of air and hydrogen, water management inside the stack, and heat management of the stack. For small PEM fuel cell stacks operated without a separate humidifier, fans are essential for air supply, heat management, and water management of the stack. A purge valve discharges surplus water from the stack. The proposed method controls the fan using a dual closed loop with a static feed-forward structure, thereby improving system efficiency and operation stability. The validity of the proposed method is confirmed by experiments using a 150-W PEM fuel cell stack. We expect the proposed algorithm to be widely used for controlling small PEM fuel cell stacks. (author)

  11. Sequential transcatheter aortic valve implantation due to valve dislodgement - a Portico valve implanted over a CoreValve bioprosthesis.

    Science.gov (United States)

    Campante Teles, Rui; Costa, Cátia; Almeida, Manuel; Brito, João; Sondergaard, Lars; Neves, José P; Abecasis, João; M Gabriel, Henrique

    2017-03-01

    Transcatheter aortic valve implantation (TAVI) has become an important treatment in high surgical risk patients with severe aortic stenosis (AS), whose complications need to be managed promptly. The authors report the case of an 86-year-old woman presenting with severe symptomatic AS, rejected for surgery due to advanced age and comorbidities. The patient underwent a first TAVI, with implantation of a Medtronic CoreValve ® , which became dislodged and migrated to the ascending aorta. Due to the previous balloon valvuloplasty, the patient's AS became moderate, and her symptoms improved. After several months, she required another intervention, performed with a St. Jude Portico ® repositionable self-expanding transcatheter aortic valve. There was a good clinical response that was maintained at one-year follow-up. The use of a self-expanding transcatheter bioprosthesis with repositioning features is a solution in cases of valve dislocation to avoid suboptimal positioning of a second implant, especially when the two valves have to be positioned overlapping or partially overlapping each other. Copyright © 2017 Sociedade Portuguesa de Cardiologia. Publicado por Elsevier España, S.L.U. All rights reserved.

  12. Cavitation noise from butterfly valves

    International Nuclear Information System (INIS)

    Rahmeyer, W.J.

    1982-01-01

    Cavitation in valves can produce levels of intense noise. It is possible to mathematically express a limit for a design level of cavitation noise in terms of the cavitation parameter sigma. Using the cavitation parameter or limit, it is then possible to calculate the flow conditions at which a design level of cavitation noise will occur. However, the intensity of cavitation increases with the upstream pressure and valve size at a constant sigma. Therefore, it is necessary to derive equations to correct or scale the cavitation limit for the effects of different upstream pressures and valve sizes. The following paper discusses and presents experimental data for the caviation noise limit as well as the cavitation limits of incipient, critical, incipient damage, and choking cavitation for butterfly valves. The main emphasis is on the design limit of caviation noise, and a noise level of 85 decibels was selected as the noise limit. Tables of data and scaling exponents are included for applying the design limits for the effects of upstream pressure and valve size. (orig.)

  13. Plunger with simple retention valve

    International Nuclear Information System (INIS)

    Fekete, A.V.

    1987-01-01

    This patent describes a positive displacement retention valve apparatus in which the actual flow equals the theoretical maximum flow through the retention valve. The apparatus includes, in combination, a confined fluid flow conduit, a piston adapted for reciprocal movement within the fluid flow conduit between upstream and downstream limit positions, piston reciprocating means, and pressure responsive check valve means located upstream with respect to the piston in the fluid flow conduit. The pressure responsive check valve means operable to permit fluid flow therethrough in a downstream direction toward the piston, and to preclude fluid flow therethrough in an opposite direction. The piston is composed of parts which are relatively movable with respect to one another. The piston includes a simple retention valve consisting of a plug means, a cylinder having a minimum and a maximum internal cross section flow area therein and being reciprocal within the confined fluid flow conduit, and a seat on the cylinder for the plug means. The piston reciprocating means are operatively connected to the plug means

  14. Structural valve deterioration in the Mitroflow biological heart valve prosthesis

    DEFF Research Database (Denmark)

    Issa, Issa Farah; Poulsen, Steen Hvitfeldt; Waziri, Farhad

    2018-01-01

    OBJECTIVES: Concern has been raised regarding the long-term durability of the Mitroflow biological heart valve prosthesis. Our aim was to assess the incidence of structural valve degeneration (SVD) for the Mitroflow bioprosthesis in a nationwide study in Denmark including all patients alive......: A total of 173 patients were diagnosed with SVD by echocardiography. Of these, 64 (11%) patients had severe SVD and 109 (19%) patients moderate SVD. Severe SVD was associated with the age of the prosthesis and small prosthesis size [Size 21: hazard ratio (95% confidence interval, CI) 2.72 (0.97-8.56), P...

  15. Development of Long-Lifetime Pulsed Gas Valves for Pulsed Electric Thrusters

    Science.gov (United States)

    Burkhardt, Wendel M.; Crapuchettes, John M.; Addona, Brad M.; Polzin, Kurt A.

    2015-01-01

    It is advantageous for gas-fed pulsed electric thrusters to employ pulsed valves so propellant is only flowing to the device during operation. The propellant utilization of the thruster will be maximized when all the gas injected into the thruster is acted upon by the fields produced by the electrical pulse. Gas that is injected too early will diffuse away from the thruster before the electrical pulse can act to accelerate the propellant. Gas that is injected too late will miss being accelerated by the already-completed electrical pulse. As a consequence, the valve must open quickly and close equally quickly, only remaining open for a short duration. In addition, the valve must have only a small amount of volume between the sealing body and the thruster so the front and back ends of the pulse are as coincident as possible with the valve cycling, with very little latent propellant remaining in the feed lines after the valve is closed. For a real mission of interest, a pulsed thruster can be expected to pulse at least 10(exp 10) - 10(exp 11) times, setting the range for the number of times a valve must open and close. The valves described in this paper have been fabricated and tested for operation in an inductive pulsed plasma thruster (IPPT) for in-space propulsion. In general, an IPPT is an electrodeless space propulsion device where a capacitor is charged to an initial voltage and then discharged, producing a high-current pulse through a coil. The field produced by this pulse ionizes propellant, inductively driving current in a plasma located near the face of the coil. Once the plasma is formed, it can be accelerated and expelled at a high exhaust velocity by the electromagnetic Lorentz body force arising from the interaction of the induced plasma current and the magnetic field produced by the current in the coil. The valve characteristics needed for the IPPT application require a fast-acting valve capable of a minimum of 10(exp 10) valve actuation cycles. Since

  16. Sliding-gate valve for use with abrasive materials

    Science.gov (United States)

    Ayers, Jr., William J.; Carter, Charles R.; Griffith, Richard A.; Loomis, Richard B.; Notestein, John E.

    1985-01-01

    The invention is a flow and pressure-sealing valve for use with abrasive solids. The valve embodies special features which provide for long, reliable operating lifetimes in solids-handling service. The valve includes upper and lower transversely slidable gates, contained in separate chambers. The upper gate provides a solids-flow control function, whereas the lower gate provides a pressure-sealing function. The lower gate is supported by means for (a) lifting that gate into sealing engagement with its seat when the gate is in its open and closed positions and (b) lowering the gate out of contact with its seat to permit abrasion-free transit of the gate between its open and closed positions. When closed, the upper gate isolates the lower gate from the solids. Because of this shielding action, the sealing surface of the lower gate is not exposed to solids during transit or when it is being lifted or lowered. The chamber containing the lower gate normally is pressurized slightly, and a sweep gas is directed inwardly across the lower-gate sealing surface during the vertical translation of the gate.

  17. Bicuspid Aortic Valve Disease: A Comprehensive Review

    OpenAIRE

    Mordi, Ify; Tzemos, Nikolaos

    2012-01-01

    Bicuspid aortic valve is the commonest congenital cardiac abnormality in the general population. This paper article will discuss our current knowledge of the anatomy, pathophysiology, genetics, and clinical aspects of bicuspid aortic valve disease.

  18. Echocardiographic evaluation of heart valve prosthetic dysfunction

    Directory of Open Access Journals (Sweden)

    Yuriy Ivaniv

    2018-02-01

    Full Text Available Patients with replaced heart valve submitted to echocardiographic examination may have symptoms related either to valvular malfunction or ventricular dysfunction from different causes. Clinical examination is not reliable in a prosthetic valve evaluation and the main information regarding its function could be obtained using different cardiac ultrasound modalities. This review provides a description of echocardiographic and Doppler techniques useful in evaluation of prosthetic heart valves. For the interpretation of echocardiography there is a need in special knowledge of prosthesis types and possible reasons of prosthetic function deterioration. Echocardiography allows to reveal valve thrombosis, pannus formation, vegetation and such complications of infective endocarditis as valve ring abscess or dehiscence. Transthoracic echocardiography requires different section plane angles and unconventional views. Transesophageal echocardiography is more often used than in native valve examination due to better visualization of prosthetic valve structure and function. Three-dimensional echocardiography could provide more detailed visual information especially in the assessment of paravalvular regurgitation or valve obstruction.

  19. Bistable fluidic valve is electrically switched

    Science.gov (United States)

    Fiet, O.; Salvinski, R. J.

    1970-01-01

    Bistable control valve is selectively switched by direct application of an electrical field to divert fluid from one output channel to another. Valve is inexpensive, has no moving parts, and operates on fluids which are relatively poor electrical conductors.

  20. Comparative study between CardiaMed valves (freely floating valve leaflets versus St. Jude Medical (fixed valve leaflets in mitral valve replacement surgery

    Directory of Open Access Journals (Sweden)

    Mostafa Ahmed

    2017-09-01

    Conclusions: CardiaMed freely floating leaflet prostheses showed good hemodynamic characteristics. The prosthesis adequately corrects hemodynamics and is safe and no worse than the St. Jude Medical valve in the mitral valve position.

  1. Prosthetic Mitral Valve Leaflet Escape

    Science.gov (United States)

    Kim, Darae; Hun, Sin Sang; Cho, In-Jeong; Shim, Chi-Young; Ha, Jong-Won; Chung, Namsik; Ju, Hyun Chul; Sohn, Jang Won

    2013-01-01

    Leaflet escape of prosthetic valve is rare but potentially life threatening. It is essential to make timely diagnosis in order to avoid mortality. Transesophageal echocardiography and cinefluoroscopy is usually diagnostic and the location of the missing leaflet can be identified by computed tomography (CT). Emergent surgical correction is mandatory. We report a case of fractured escape of Edward-Duromedics mitral valve 27 years after the surgery. The patient presented with symptoms of acute decompensated heart failure and cardiogenic shock. She was instantly intubated and mechanically ventilated. After prompt evaluation including transthoracic echocardiography and CT, the escape of the leaflet was confirmed. The patient underwent emergent surgery for replacement of the damaged prosthetic valves immediately. Eleven days after the surgery, the dislodged leaflet in iliac artery was removed safely and the patient recovered well. PMID:23837121

  2. Active combustion flow modulation valve

    Science.gov (United States)

    Hensel, John Peter; Black, Nathaniel; Thorton, Jimmy Dean; Vipperman, Jeffrey Stuart; Lambeth, David N; Clark, William W

    2013-09-24

    A flow modulation valve has a slidably translating hollow armature with at least one energizable coil wound around and fixably attached to the hollow armature. The energizable coil or coils are influenced by at least one permanent magnet surrounding the hollow armature and supported by an outer casing. Lorentz forces on the energizable coils which are translated to the hollow armature, increase or decrease the flow area to provide flow throttling action. The extent of hollow armature translation depends on the value of current supplied and the direction of translation depends on the direction of current flow. The compact nature of the flow modulation valve combined with the high forces afforded by the actuator design provide a flow modulation valve which is highly responsive to high-rate input control signals.

  3. Statins for aortic valve stenosis

    Directory of Open Access Journals (Sweden)

    Luciana Thiago

    Full Text Available ABSTRACT BACKGROUND: Aortic valve stenosis is the most common type of valvular heart disease in the USA and Europe. Aortic valve stenosis is considered similar to atherosclerotic disease. Some studies have evaluated statins for aortic valve stenosis. OBJECTIVES: To evaluate the effectiveness and safety of statins in aortic valve stenosis. METHODS: Search methods: We searched the Cochrane Central Register of Controlled Trials (CENTRAL, MEDLINE, Embase, LILACS - IBECS, Web of Science and CINAHL Plus. These databases were searched from their inception to 24 November 2015. We also searched trials in registers for ongoing trials. We used no language restrictions. Selection criteria: Randomized controlled clinical trials (RCTs comparing statins alone or in association with other systemic drugs to reduce cholesterol levels versus placebo or usual care. Data collection and analysis: Primary outcomes were severity of aortic valve stenosis (evaluated by echocardiographic criteria: mean pressure gradient, valve area and aortic jet velocity, freedom from valve replacement and death from cardiovascular cause. Secondary outcomes were hospitalization for any reason, overall mortality, adverse events and patient quality of life. Two review authors independently selected trials for inclusion, extracted data and assessed the risk of bias. The GRADE methodology was employed to assess the quality of result findings and the GRADE profiler (GRADEPRO was used to import data from Review Manager 5.3 to create a 'Summary of findings' table. MAIN RESULTS: We included four RCTs with 2360 participants comparing statins (1185 participants with placebo (1175 participants. We found low-quality evidence for our primary outcome of severity of aortic valve stenosis, evaluated by mean pressure gradient (mean difference (MD -0.54, 95% confidence interval (CI -1.88 to 0.80; participants = 1935; studies = 2, valve area (MD -0.07, 95% CI -0.28 to 0.14; participants = 127; studies = 2

  4. Statins for aortic valve stenosis.

    Science.gov (United States)

    Thiago, Luciana; Tsuji, Selma Rumiko; Nyong, Jonathan; Puga, Maria Eduarda Dos Santos; Góis, Aécio Flávio Teixeira de; Macedo, Cristiane Rufino; Valente, Orsine; Atallah, Álvaro Nagib

    2016-01-01

    Aortic valve stenosis is the most common type of valvular heart disease in the USA and Europe. Aortic valve stenosis is considered similar to atherosclerotic disease. Some studies have evaluated statins for aortic valve stenosis. To evaluate the effectiveness and safety of statins in aortic valve stenosis. Search methods: We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, LILACS - IBECS, Web of Science and CINAHL Plus. These databases were searched from their inception to 24 November 2015. We also searched trials in registers for ongoing trials. We used no language restrictions.Selection criteria: Randomized controlled clinical trials (RCTs) comparing statins alone or in association with other systemic drugs to reduce cholesterol levels versus placebo or usual care. Data collection and analysis: Primary outcomes were severity of aortic valve stenosis (evaluated by echocardiographic criteria: mean pressure gradient, valve area and aortic jet velocity), freedom from valve replacement and death from cardiovascular cause. Secondary outcomes were hospitalization for any reason, overall mortality, adverse events and patient quality of life.Two review authors independently selected trials for inclusion, extracted data and assessed the risk of bias. The GRADE methodology was employed to assess the quality of result findings and the GRADE profiler (GRADEPRO) was used to import data from Review Manager 5.3 to create a 'Summary of findings' table. We included four RCTs with 2360 participants comparing statins (1185 participants) with placebo (1175 participants). We found low-quality evidence for our primary outcome of severity of aortic valve stenosis, evaluated by mean pressure gradient (mean difference (MD) -0.54, 95% confidence interval (CI) -1.88 to 0.80; participants = 1935; studies = 2), valve area (MD -0.07, 95% CI -0.28 to 0.14; participants = 127; studies = 2), and aortic jet velocity (MD -0.06, 95% CI -0.26 to 0

  5. Evaluation of mispositioned ECCS valves

    International Nuclear Information System (INIS)

    Hill, R.A.; O'Brien, J.F.; McIntire, D.C.; Barlow, R.T.

    1977-09-01

    In October of 1975, Westinghouse submitted NS-CE-787, dated October 17, 1975, to the Nuclear Regulatory Commission (NRC) and entered into discussions with them concerning the spurious movement of certain motor-operated valves (MOV's) in the Emergency Core Cooling System (ECCS) to a position defeating the ECCS function at a time when this function is required. On November 25, 1975, the discussion turned to the possible movement of a manually controlled, motor-operated valve due to a fault in its electrical circuitry and the NRC staff expressed concerns about other possible failure modes that might lead to such a valve movement. The NRC meeting minutes document these concerns. This report is an item-by-item response to the concerns expressed by the NRC staff at that meeting and incorporates the original electrical fault analysis

  6. Pannus Formation Leads to Valve Malfunction in the Tricuspid Position 19 Years after Triple Valve Replacement.

    Science.gov (United States)

    Alskaf, Ebraham; McConkey, Hannah; Laskar, Nabila; Kardos, Attila

    2016-06-20

    The Medtronic ATS Open Pivot mechanical valve has been successfully used in heart valve surgery for more than two decades. We present the case of a patient who, 19 years following a tricuspid valve replacement with an ATS prosthesis as part of a triple valve operation following infective endocarditis, developed severe tricuspid regurgitation due to pannus formation.

  7. The nordic aortic valve intervention (NOTION) trial comparing transcatheter versus surgical valve implantation

    DEFF Research Database (Denmark)

    Thyregod, Hans Gustav; Søndergaard, Lars; Ihlemann, Nikolaj

    2013-01-01

    Degenerative aortic valve (AV) stenosis is the most prevalent heart valve disease in the western world. Surgical aortic valve replacement (SAVR) has until recently been the standard of treatment for patients with severe AV stenosis. Whether transcatheter aortic valve implantation (TAVI) can...

  8. Early clinical outcome of aortic transcatheter valve-in-valve implantation in the Nordic countries

    DEFF Research Database (Denmark)

    Ihlberg, Leo; Nissen, Henrik Hoffmann; Nielsen, Niels Erik

    2013-01-01

    Transcatheter valve-in-valve implantation has emerged as an option, in addition to reoperative surgical aortic valve replacement, to treat failed biologic heart valve substitutes. However, the clinical experience with this approach is still limited. We report the comprehensive experience...

  9. Intro to Valve Guide Reconditioning. Automotive Mechanics. Valves. Instructor's Guide [and] Student Guide.

    Science.gov (United States)

    Horner, W.

    This instructional package, one in a series of individualized instructional units on tools and techniques for repairing worn valve guides in motor vehicles, provides practical experience for students in working on cylinder heads. Covered in the module are reaming valve guides that are oversized to match a new oversized valve, reaming valve guides…

  10. Infective Endocarditis of the Aortic Valve with Anterior Mitral Valve Leaflet Aneurysm

    NARCIS (Netherlands)

    Tomsic, Anton; Li, Wilson W. L.; van Paridon, Marieke; Bindraban, Navin R.; de Mol, Bas A. J. M.

    2016-01-01

    Mitral valve leaflet aneurysm is a rare and potentially devastating complication of aortic valve endocarditis. We report the case of a 48-year-old man who had endocarditis of the native aortic valve and a concomitant aneurysm of the anterior mitral valve leaflet. Severe mitral regurgitation occurred

  11. 46 CFR 56.50-70 - Gasoline fuel systems.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Gasoline fuel systems. 56.50-70 Section 56.50-70... APPURTENANCES Design Requirements Pertaining to Specific Systems § 56.50-70 Gasoline fuel systems. (a) Material.... Outlets in fuel lines for drawing gasoline for any purpose are prohibited. Valved openings in the bottom...

  12. Nuclear fuel elements

    International Nuclear Information System (INIS)

    Nakai, Keiichi

    1983-01-01

    Purpose: To decrease the tensile stresses resulted in a fuel can as well as prevent decladding of fuel pellets into the bore holes by decreasing the inner pressure within the nuclear fuel element. Constitution: A fuel can is filled with hollow fuel pellets, inserted with a spring for retaining the hollow fuel pellets with an appropriate force and, thereafter, closely sealed at the both ends with end plugs. A cylindrical body is disposed into the bore holes of the hollow fuel pellets. Since initial sealing gases and/or gaseous nuclear fission products can thus be excluded from the bore holes where the temperature is at the highest level, the inner pressure of the nuclear fuel element can be reduced to decrease the tensile strength resulted to the fuel can. Furthermore, decladding of fuel pellets into the bore holes can be prevented. (Moriyama, K.)

  13. Small sodium valve design and operating experience

    International Nuclear Information System (INIS)

    McGough, C.B.

    1974-01-01

    The United States Liquid Metal Fast Breeder Reactor program (LMFBR) includes an extensive program devoted to the development of small sodium valves. This program is now focused on the development and production of valves for the Fast Flux Test Facility (FFTF) now under construction near Richland, Washington. Other AEC support facilities, such as various test loops located at the Liquid Metal Engineering Center (LMEC), Los Angeles, California, and at the Hanford Engineering Development Laboratory (HEDL), Richland, Washington, also have significant requirements for small sodium valves, and valves similar in design to the FFTF valves are being supplied to these AEC laboratories for use in their critical test installations. A principal motivation for these valve programs, beyond the immediate need to provide high-reliability valves for FFTF and the support facilities, is the necessity to develop small valve technology for the Clinch River Breeder Reactor Plant (CRBRP). FFTF small sodium valve design and development experience will be directly applied to the CRBRP program. Various test programs have been, and are being, conducted to verify the performance and integrity of the FFTF valves, and to uncover any potential problems so that they can be corrected before the valves are placed in service in FFTF. The principal small sodium valve designs being utilized in current U.S. programs, the test and operational experience obtained to date on them, problems uncovered, and future development and testing efforts being planned are reviewed. The standards and requirements to which the valves are being designed and fabricated, the valve designs in current use, valve operators, test and operating experience, and future valve development plans are summarized. (U.S.)

  14. Promising results after percutaneous mitral valve repair

    DEFF Research Database (Denmark)

    Ihlemann, Nikolaj; Franzen, Olaf; Jørgensen, Erik

    2011-01-01

    Mitral valve regurgitation (MR) is the secondmost frequent valve disease in Europe. Untreated MR causes considerable morbidity and mortality. In the elderly, as many as half of these patients are denied surgery because of an estimated high surgical risk. Percutaneous mitral valve repair with the ...... with the MitraClip system resembles the Alfieristitch where a clip is used to connect the tip of the mitral valve leaflets....

  15. Infective endocarditis following percutaneous pulmonary valve replacement

    DEFF Research Database (Denmark)

    Cheung, Gary; Vejlstrup, Niels; Ihlemann, Nikolaj

    2013-01-01

    Infective endocarditis (IE) following percutaneous pulmonary valve replacement (PPVR) with the Melody valve is rarely reported. Furthermore, there are challenges in this diagnosis; especially echocardiographic evidence of vegetation within the prosthesis may be difficult.......Infective endocarditis (IE) following percutaneous pulmonary valve replacement (PPVR) with the Melody valve is rarely reported. Furthermore, there are challenges in this diagnosis; especially echocardiographic evidence of vegetation within the prosthesis may be difficult....

  16. Development of a discharge model for the Bopp and Reuther Degasser/Condenser relief valves for heat sink assessment

    International Nuclear Information System (INIS)

    Hasnaoui, C. . chiheb@hasnaoui.net; Huynh, M.

    2004-01-01

    A total loss of all sustained engineering heat sinks is considered as a severe accident with low probability of occurrence. Following a total loss of all sustained engineering heat sinks, the Degasser/Condenser relief valves (3332-RV11 and RV21) would then become the sole means available for the depressurization of the primary heat transport system. Accurate estimation of the discharge through these valves is required to assess the impact of this kind of accident on fuel cooling and the primary circuit integrity. This paper describes a model used to estimate the Degasser/Condenser relief valve discharge capacity. This model is used to predict the flow discharge under a range of conditions upstream of the relief valves; from sub-cooled to saturated liquid and up to vapor conditions. The defined model is then used to estimate the relief valve discharge rates under various hypothetical conditions of the PHTS using the Cathena code. (author)

  17. Application Of Light Valves For Continuous-Tone Printing

    Science.gov (United States)

    Vergona, Albert B.

    1989-07-01

    New opportunities are emerging in the graphic-arts pre-press market stimulated by the need for digitally created images. To meet this need, we have designed a cost-effective three-color digital printer using PLZT light valves. Transparent lead lanthanum zirconate titanate (PLZT) ceramic crystals when used as a linear modulator offer a number of significant benefits. The primary advantage is that the light valve is an efficient modulator of incoherent light providing a broad spectral output ranging from 400nm to well into the infrared region. In addition, light valves offer the advantages of being small, low cost, have a wide dynamic range (>1000 to 1), and can be used with simple optical designs. The characteristics of the PLZT material plays an important role in the performance of the light valve. A number of variables such as ceramic composition, electrode spacing, and ceramic thickness can be altered to affect its quadratic electrooptic behavior. Additionally, the modulator design requires a closed-loop servo to eliminate the errors caused by the device's remanent polarization and nonlinear behavior.

  18. The effect of lymphatic valve morphology on fluid transport

    Science.gov (United States)

    Alexeev, Alexander; Ballard, Matthew; Nepiyushchikh, Zhanna; Dixon, Brandon

    2016-11-01

    The lymphatic vasculature is present in nearly all invertebrate tissue, and is essential in the transport of fluid and particles such as immune cells, antigens, proteins and lipids from the tissue to lymph nodes and to the venous circulation. Lymphatic vessels are made of up a series of contractile units that work together in harmony as "micro hearts" to pump fluid against a pressure gradient. Lymphatic valves are critical to this functionality, as they open and close with the oscillating pressure gradients from contractions, thus allowing flow in only one direction and leading to a net pumping effect. We use a hybrid lattice-Boltzmann lattice spring model which captures fluid-solid interactions through two-way coupling between a viscous fluid and lymphatic valves in a section of a lymphatic vessel to study the dynamics of lymphatic valves and their effect on fluid transport. Further, we investigate the effect of variations in valve geometry and material properties on fluid pumping. This work helps to increase our understanding of the mechanisms of lymphatic fluid transport, which has implications in a variety of pathologies, including cancer metastasis, autoimmunity, atherosclerosis and obesity. Support from NSF CMMI 1635133 is gratefully acknowledged.

  19. Hydraulic System Design of Hydraulic Actuators for Large Butterfly Valves

    Directory of Open Access Journals (Sweden)

    Ye HUANG

    2014-09-01

    Full Text Available Hydraulic control systems of butterfly valves are presently valve-controlled and pump-controlled. Valve-controlled hydraulic systems have serious power loss and generate much heat during throttling. Pump-controlled hydraulic systems have no overflow or throttling losses but are limited in the speed adjustment of the variable-displacement pump, generate much noise, pollute the environment, and have motor power that does not match load requirements, resulting in low efficiency under light loads and wearing of the variable-displacement pump. To overcome these shortcomings, this article designs a closed hydraulic control system in which an AC servo motor drives a quantitative pump that controls a spiral swinging hydraulic cylinder, and analyzes and calculates the structure and parameters of a spiral swinging hydraulic cylinder. The hydraulic system adjusts the servo motor’s speed according to the requirements of the control system, and the motor power matches the power provided to components, thus eliminating the throttling loss of hydraulic circuits. The system is compact, produces a large output force, provides stable transmission, has a quick response, and is suitable as a hydraulic control system of a large butterfly valve.

  20. 49 CFR 195.260 - Valves: Location.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Valves: Location. 195.260 Section 195.260... PIPELINE Construction § 195.260 Valves: Location. A valve must be installed at each of the following locations: (a) On the suction end and the discharge end of a pump station in a manner that permits isolation...