The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
Kyeong Mo Hwang - One of the best experts on this subject based on the ideXlab platform.
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Fluid Mixing Analysis for Predicting Shell Wall Thinning of a Feedwater Heater
Journal of Mechanical Science and Technology, 2020Co-Authors: Kyeong Mo HwangAbstract:Feedwater flowing in the tube side of the number 5 high pressure Feedwater Heaters is heated by extraction steam from the high pressure turbine and drain water from the moisture separators and the number 6 high pressure Feedwater Heaters and supplied into the steam generators. Because the extraction steam from the high pressure turbine is a two phase fluid of high temperature, high pressure, and high speed and changes direction after colliding with the impingement baffle, the shell wall of the number 5 high pressure Feedwater Heaters may be subjected to flow-accelerated corrosion. Wall thinning damage caused by the flow-accelerated corrosion has primarily occurred in carbon and low alloy steel piping. Components, such as Feedwater Heaters, condensers, etc., however, have recently experienced severe wall thinning damage, which will increase as operating time progresses. This paper describes the fluid mixing analysis study using PHOENICS code in order to determine root cause of the shell wall thinning of the Feedwater Heaters. To identify the relation between the wall thinning and the fluid behavior, the local velocity components in the x-, y-, and z-direction were compared with the wall thickness data by ultrasonic test.
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shell wall thinning and mitigation plan and design modification of a Feedwater Heater impingement baffle
Journal of the Korean Society for Precision Engineering, 2010Co-Authors: Kyeong Mo Hwang, Sanghoon ParkAbstract:Feedwater Heaters of many nuclear power plants have recently experienced severe wall thinning damage, which will increase as operating time progresses. Several nuclear power plants in Korea have experienced wall thinning damage in the area around the impingement baffle inside Feedwater Heater installed downstream of the turbine extraction stream line. At that point, the extract steam from the turbine is two phase fluid at high temperature, high pressure, and high speed. Since it flows to reverse direction after impinging the impingement baffle, the shell wall of Feedwater Heaters may be affected by flow-accelerated corrosion. In this paper, to compare degree of shell wall thinning mitigation rate to squared type with mitigation rate of other type baffle plate, three different types of impingement baffle plate-squared, curved and mitigating type-applied inside the shell. With these comparison data, this paper describes operation of experiments and numerical analysis which is composed similar condition with real feed water Heater. And flow visualization is operated for verification of experiments and numerical analysis. In conclusion, this study shows that mitigating type baffle plate is more effective than other baffle plate about prevention of pressure concentration and pressure value decrease.
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a study on the shell wall thinning by flow acceleration corrosion and mitigation plan and design modification of a Feedwater Heater impingement baffle
Journal of ILASS-Korea, 2010Co-Authors: Kyeong Mo HwangAbstract:Feedwater Heaters of many nuclear power plants have recently experienced severe wall thinning damage, which will increase as operating time progresses. Several nuclear power plants in Korea have experienced wall thinning damage in the area around the impingement baffle inside Feedwater Heater installed downstream of the turbine extraction stream line. At that point, the extract steam from the turbine is two phase fluid at high temperature, high pressure, and high speed. Since it flows to reverse direction after impinging the impingement baffle, the shell wall of Feedwater Heaters may be affected by flow-accelerated corrosion. In this paper, to compare degree of shell wall thinning mitigation rate to squared type with mitigation rate of other type baffle plate, four different types of impingement baffle plate-squared, curved, mitigating type and multi-hole type-applied inside the shell. With these comparison data, this paper describes operation of experiments and numerical analysis which is composed similar condition with real feed water Heater. And flow visualization is operated for verification of experiments and numerical analysis. In conclusion, this study shows that mitigating type and multi-hole type baffle plate are more effective than other baffle plate about prevention of pressure concentration and pressure value decrease.
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design modification and correlation verification between reattachment flow of dispersed jet and local thinning of Feedwater Heater
Korean Journal of Air-Conditioning and Refrigeration Engineering, 2009Co-Authors: Kyeong Mo HwangAbstract:Feedwater Heaters of many nuclear power plants have recently experienced severe wall thinning damange, which will increase as operating time progresses. Several nuclear power plants in Korea have experienced wall thinning damage in the area around the impingement baffle-installed downstream of the high pressure turbine extraction stream line-inside number 5A and 5B Feedwater Heaters. At that point, the extracted steam from the high pressure turbine is two phase fluid at high temperature, high pressure, and high speed. Since it flows in reverse direction after impinging the impingement baffle, the shell wall of the number 5 high pressure Feedwater Heater may be affected by flow-accelerated corrosion. This paper describes operation of experience and numerical analysis composed similar condition with real high pressure Feedwater Heater. This study applied squared, curved and new type impingement baffle plates to Feedwater Heater same as previous study. In addition, it shows difference of pressure distribution and value between single phase and two phase based on experience and numerical analysis.
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a study on the shell wall thinning causes identified through experiment numerical analysis and ultrasonic test of high pressure Feedwater Heater
Nuclear Engineering and Design, 2008Co-Authors: Kyeong Mo HwangAbstract:Abstract Feedwater Heaters of many nuclear power plants have recently experienced severe wall thinning damage, which accelerates as the operation progresses. Several nuclear power plants in Korea have undergone this damage around the impingement baffle – installed downstream of the high-pressure turbine extraction steam line – inside numbers 5A and 5B Feedwater Heaters. At that point, the extracted steam from the high-pressure turbine consists in the form of two-phase fluid at high temperature, high pressure and high velocity. Since it flows in reverse direction after impinging the impingement baffle, the shell wall of number 5 high-pressure Feedwater Heater may be affected by flow-accelerated corrosion. This paper describes the comparisons between the numerical analysis results using the FLUENT code and the downscaled experimental data in an effort to determine root causes of the shell wall thinning of the high-pressure Feedwater Heaters. The numerical analysis and experimental data were also confirmed by the actual wall thickness measured by ultrasonic tests. From the comparison of the results for the local velocity profiles and the wall thinning measurements, the local velocity component only in the y -direction flowing vertically to the shell wall, and not in the x - and z -directions, was analogous to the wall thinning data.
M.c. Catapano - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of NDE techniques for type 439 stainless steel Feedwater Heater tubing
1995Co-Authors: M.j. Nugent, M.c. CatapanoAbstract:Ferritic stainless steel has been finding increased application in utility plant Feedwater Heaters due to good strength and corrosion resistance and absence of potential copper contamination of Feedwater system. Ferritic stainless steel is highly magnetic and is generally not inspectable using conventional eddy current testing techniques. A variety of techniques have been developed for inspection of this tubing material used in typical heat exchanger applications. Through a project completely funded by the Empire State Electric Energy Research Corporation (ESEERCO), the data generated by four present state of the art NDE testing techniques was evaluated on a controlled mock-up of the Heater tubing with service related defects. The primary objective was to determine the strengths and limitations of each method. The testing of two (2) in service Feedwater Heaters at the Consolidated Edison Company of New York, Inc. (Con Edison`s) Arthur Kill Generating Station also allowed further evaluations based on actual field conditions.
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Evaluation of examination techniques for ferritic stainless steel Feedwater Heater tubing
1995Co-Authors: M.j. Nugent, M.c. CatapanoAbstract:Ferritic stainless steel has been finding increased application in utility plant Feedwater Heaters due to good strength and corrosion resistance and absence of potential copper contamination of Feedwater system. Ferritic stainless steel is highly magnetic and is generally not inspectable using conventional eddy current testing techniques. A variety of techniques have been developed for inspection of this tubing material used in typical heat exchanger applications. Through a project funded by the Empire State Electric Energy Research Corporation (ESEERCO), the evaluation of data generated by four present state of the art NDE testing techniques were evaluated on a controlled mock-up of the Heater tubing with service related defects. The primary objective was to determine the strengths and limitations of each method. The testing of two in service Feedwater Heaters at the Consolidated Edison Company of New York, Inc. (Con Edison`s) Arthur Kill Generating Station also allowed further evaluations based on actual field conditions.
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Feedwater Heaters: Replacement specification guidelines
1990Co-Authors: F.l. Wadsworth, M.c. CatapanoAbstract:This report provides guidance and background material for utilities to assist them in developing improved specifications for procurement of replacement Feedwater Heaters. State-of-the-art recommendations and examples are described based upon recent developments in selected specifications actually used by utilities with aggressive Feedwater Heater maintenance programs. A significant portion of the guidelines are presented in typical specification format and wording, with explanatory notes. The report also stresses the shortcomings of the procurement processes which have been identified as root causes of poor quality and premature failures of Feedwater Heaters. Specific recommendations are offered for utility management to initiate remedial actions, working with suppliers and regulators to resolve this problem. Until the procurement system is improved, utilities will need comprehensive, detailed procurement specifications. 1 fig.
J.m. Bailey - One of the best experts on this subject based on the ideXlab platform.
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lqg ltr control system design for a low pressure Feedwater Heater train with time delay
Conference of the Industrial Electronics Society, 1990Co-Authors: G.v. Murphy, J.m. BaileyAbstract:An LQG/LTR control system design is formulated for a nuclear reactor Feedwater Heater train with output time delay. This approach involves factoring the Feedwater Heater train plant into nonminimum and minimum-phase components to allow the design of a robust controller for the minimum-phase component of the plant using the LQG/LTR technique. The nonminimum phase component takes the form of an all-pass filter containing the RHP zeroes of the first-order approximation of the time-delay component. Using this nonminimum phase all-pass filter, certain singular-value multiplicative error bounds can be established to obtain a stable control system when using the LQG/LTR design technique on the minimum-phase component of the plant. Novel analysis methods using singular values are integrated into the conventional singular-value performance and stability robustness analysis procedure. These methods allow computation of the maximum allowable time delay before instability occurs for both SISO and MIMO (single-input-single-output and multiple-input-multiple-output) control systems. >
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LQG/LTR robust control system design for low-pressure Feedwater Heater train
IEEE Proceedings on Southeastcon, 1990Co-Authors: G.v. Murphy, J.m. BaileyAbstract:The linear quadratic Gaussian with loop transfer recovery (LQG/LTR) control system design method is used to obtain a level control system for a nuclear plant low-pressure Feedwater Heater train. A control system design for robustness at the plant output is developed. Its performance and stability robustness are evaluated for given specifications. The tools for analysis are the return ratio, return difference, and inverse return difference singular-value plots for a loop break at the plant output. These singular-value plots are examined. The LQG/LTR control system design procedure allows the synthesis of a low-pressure Feedwater Heater train level control system that meets certain frequency-domain design specifications. In this case, by only using the inherent integral type of action that deviates slightly from the ideal integral action, plant integral augmentation is avoided. Using these plant dynamics results in command following of one Feedwater tank level with a slight steady-state error, which is expected. since pure integrals did not exist in the plant. The design of this robust control system shows that a desirable low-pressure Feedwater Heater train level control system is obtainable using the LQG/LTR procedure.
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lqg ltr robust control system design for low pressure Feedwater Heater train
SoutheastCon, 1990Co-Authors: G.v. Murphy, J.m. BaileyAbstract:The linear quadratic Gaussian with loop transfer recovery (LQG/LTR) control system design method is used to obtain a level control system for a nuclear plant low-pressure Feedwater Heater train. A control system design for robustness at the plant output is developed. Its performance and stability robustness are evaluated for given specifications. The tools for analysis are the return ratio, return difference, and inverse return difference singular-value plots for a loop break at the plant output. These singular-value plots are examined. The LQG/LTR control system design procedure allows the synthesis of a low-pressure Feedwater Heater train level control system that meets certain frequency-domain design specifications. In this case, by only using the inherent integral type of action that deviates slightly from the ideal integral action, plant integral augmentation is avoided. Using these plant dynamics results in command following of one Feedwater tank level with a slight steady-state error, which is expected. since pure integrals did not exist in the plant. The design of this robust control system shows that a desirable low-pressure Feedwater Heater train level control system is obtainable using the LQG/LTR procedure. >
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LQG/LTR control system design for a low-pressure Feedwater Heater train with time delay
[Proceedings] IECON '90: 16th Annual Conference of IEEE Industrial Electronics Society, 1990Co-Authors: G.v. Murphy, J.m. BaileyAbstract:An LQG/LTR control system design is formulated for a nuclear reactor Feedwater Heater train with output time delay. This approach involves factoring the Feedwater Heater train plant into nonminimum and minimum-phase components to allow the design of a robust controller for the minimum-phase component of the plant using the LQG/LTR technique. The nonminimum phase component takes the form of an all-pass filter containing the RHP zeroes of the first-order approximation of the time-delay component. Using this nonminimum phase all-pass filter, certain singular-value multiplicative error bounds can be established to obtain a stable control system when using the LQG/LTR design technique on the minimum-phase component of the plant. Novel analysis methods using singular values are integrated into the conventional singular-value performance and stability robustness analysis procedure. These methods allow computation of the maximum allowable time delay before instability occurs for both SISO and MIMO (single-input-single-output and multiple-input-multiple-output) control systems.
Stanley Yokell - One of the best experts on this subject based on the ideXlab platform.
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Note on Shear Load-Testing Feedwater Heater Tube Joints
Journal of Pressure Vessel Technology-transactions of The Asme, 2007Co-Authors: Stanley YokellAbstract:This paper describes some results of shear load testing of welded and hybrid expanded tube-to-tube-sheet joints. The construction consisted of strength welding SA-688-TP 304N tubes to SA350LF-2 tube sheets clad with stainless-steel type 308/309 weld wire followed by hybrid expanding the tubes into the full thickness of thick double-grooved tube sheets. The author theorizes that the mechanism that led to all failures reported to have occurred in the welds/heat-affected zones instead of the anticipated tube yielding resulted from loss of interfacial pressure between the expanded tubes and surrounding ligaments. The author further speculates that elastic and plastic tube deformation during application of axial loads during shear load testing caused loss of interfacial pressure, which eliminated the holding capacity of the expanded-in length of tubes and that there was sufficient flattening of the tube metal deformed into the annular grooves to permit the applied loads to be carried to the welds.
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Proper use of wall loss criteria for determining when to plug non-leaking Feedwater Heater tubes
Power Engineering, 2001Co-Authors: Carl F. Andreone, Stanley YokellAbstract:At one time or another, most purchasers, operators and maintainers of closed Feedwater Heaters ask themselves the following question: At what wall loss percentage should tubes be plugged to avoid tube failures between scheduled outages? This is an incomplete question, however, because it ignores other equally important criteria: the rate at which wall loss is occurring, inspection inaccuracies, related degrading mechanisms, and the types and characteristics of defects. This article describes how to use wall loss criterion to determine when to plug Feedwater Heater tubes.
V. P. Kanishchev - One of the best experts on this subject based on the ideXlab platform.
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The condensation of steam from steam-water mixture on water jets at high pressure
Thermal Engineering, 2009Co-Authors: E. V. Somova, V. I. Kisina, A. L. Shvarts, A. V. Kolbasnikov, V. P. KanishchevAbstract:A physical model for condensation of steam in water flow at high pressure is developed, and analytical dependences for calculating heat transfer are obtained, in particular as applied to the operation of a direct-contact Feedwater Heater for a new-generation reactor plant with lead coolant.
