Structural Dynamic Transient Analysis of Fire Protection System at a Nuclear Power Plant

2018 ◽  
Author(s):  
Milton Dong ◽  
Eugene Tom
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Fire Protection ◽  
Nuclear Power ◽  
Water Hammer ◽  
Protection System ◽  
Structural Dynamic ◽  
Piping Systems ◽  
Sample System ◽  
Fire Protection System

NRC Information Notice 98-31[1] describes a water hammer event that occurred at Columbia Generating Station. In this event, actuation of a Fire Protection System (FPS) led to voiding in a tall dead-ended riser with subsequent water hammer in the riser when the main fire pumps were activated. Due to the severity of the event, NRC requires that FPS with similar configurations at other nuclear power plants be analyzed for similar events. This paper describes an evaluation of two selected riser piping systems performed to quantify the susceptibility of the potential water hammer events in the FPS at a nuclear power plant. The FPS was modeled in a proprietary computer program, USLAM (Hydraulic Analysis Code), and selected operational scenarios (analysis cases) were analyzed to quantify the potential waterhammer loads (fluid forces). A tall riser piping system in the Reactor Building was chosen as a sample system for structural dynamic analysis. Based on the results of the sample system, it was concluded that the fire protection piping systems could experience piping stress far exceed the faulted allowable loads as allowed by the ASME/ANSI piping code. A cost-effective mitigation scheme was then proposed plan in paper ICONE65-82622[2] as Part 1 of this study with consideration only hydraulic loading where 11 vacuum breakers are to be installed at various locations of the FPS. The structural analyses discussed only piping stress in this paper and demonstrate for the effectiveness of the proposed mitigation scheme from the revised hydrodynamic loads. As the continuation of Ref. 2, the results from this study validate the acceptance of these two piping systems.

Transient Analysis of Fire Protection System at a Nuclear Power Plant Using Computer Code USLAM

2018 ◽  
Author(s):  
Asif H. Arastu ◽  
Eugene Tom
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Fire Protection ◽  
Nuclear Power ◽  
Computer Code ◽  
Water Hammer ◽  
Protection System ◽  
Operating Modes ◽  
Effective Manner ◽  
Fire Protection System

A new Method Of Characteristics (MOC) based computer code, USLAM, has been used to analyze the Fire Protection System (FPS) of a Nuclear Power Plant. Some unique features of this system are that it has a complex geometry, has many operating modes, is connected to an adjacent nuclear power plant FPS, and has a significant number of high elevation standpipes or risers. In a typical FPS, firefighting water is pumped from a low elevation reservoir at atmospheric pressure to the whole system including higher elevations regions where water hammer due to water column separation & rejoining may occur. A low capacity keep-full system is employed to keep the system pressurized during standby conditions. A loss of system pressure due to the opening of the pre-action or deluge valves can lead to void formation at high elevations whose collapse can result in severe water hammer. A catastrophic valve failure due to a water hammer event at a nuclear power plant (Arastu, et al, 1999) disabled the entire FPS. The analysis presented in this paper is to evaluate the possibility of such a water hammer event and mitigate it in an effective manner. The mitigation method employed is the use of multiple vacuum breakers. As many as 11 vacuum breakers are used for this purpose. The paper discusses the analysis results without and with vacuum breakers for all operating modes. The basic methodology of the USLAM code is also discussed.

Waterhammer Analysis of Fire Protection System Due to Draining of High Elevation Headers

2002 ◽  
Author(s):  
S. Mahmood Husaini ◽  
Riyad K. Qashu ◽  
David Y. Arai ◽  
Jeffrey S. Summy
Keyword(s):  
Fire Protection ◽  
Nuclear Power ◽  
Power Plants ◽  
High Elevation ◽  
Sprinkler System ◽  
Water Hammer ◽  
Protection System ◽  
Hydraulic Analysis ◽  
Forcing Functions ◽  
Fire Protection System

This paper presents a methodology for analyzing the potential for water hammer in fire protection systems of nuclear power plants due to draining of high elevation headers. A transient thermal hydraulic analysis was performed that modeled the combined San Onofre Nuclear Generating Station (SONGS) Units 2 and 3 Fire Protection System in general and the high elevation piping in minute detail. The purpose of this analysis was to simulate a postulated scenario that actuates a sprinkler system resulting in the draining of high elevation headers, followed by the start up of the main pumps. The analysis was based on a generalized computer program that utilizes the Method of Characteristics (MOC) numerical scheme. The forcing functions generated by the hydraulic analyses indicated that some hangers would be over loaded. In order to mitigate the water hammer and reduce the loads, the system was analyzed by modeling vacuum breakers at selected locations. The cushioning effect of the air introduced into the system by using vacuum breakers was found to significantly reduce the intensity of the water hammer. Subsequent stress and pipe support analysis predicted there will be no damage to the hangers. The details of the hydraulic analysis, such as the model, pressure and velocity time histories at selected locations, and forcing functions for the cases with and without vacuum breakers are included. Only the conclusions of the stress and pipe support analysis are presented.

Design of the Communication Independence for ACPR1000 Nuclear Power Plant Digital Safety I&C System

2017 ◽  
Author(s):  
Sun Na ◽  
Shi Gui-lian ◽  
Xie Yi-qin ◽  
Li Gang ◽  
Jiang Guo-jin
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Communication Networks ◽  
Nuclear Power ◽  
Protection System ◽  
Plant Safety ◽  
Safety And Reliability ◽  
Digital Protection ◽  
Architecture And Design ◽  
Reactor Protection System

Communication independence is one of the key criteria of digital safety I&C system design. This paper mainly analyzes the requirements for communication independence in safety regulations and standards, and then introduces the architecture and design features, including communication failure processing measures, of communication networks of ACPR1000 nuclear power plant safety digital protection system based on FirmSys platform developed by CTEC. The communication design meets the regulations requirements and effectively improves the safety and reliability of the system, and it is successfully applied in reactor protection system (RPS) of Yang Jiang nuclear power plant unit 5&6. In addition this design can provide reference for communication designs of other NPPs and industries.

Water Hammer Characteristics for Parallel Pumps Water Supply Systems

2008 ◽  
Author(s):  
Wenxi Tian ◽  
Guanghui Su ◽  
Suizheng Qiu ◽  
Gaopeng Wang ◽  
Qing Lu
Keyword(s):  
Power Plant ◽  
Nuclear Power Plant ◽  
Water Supply ◽  
High Speed ◽  
Nuclear Power ◽  
Optimization Design ◽  
Check Valve ◽  
Water Hammer ◽  
Characteristic Line ◽  
Water Supply Systems

The water hammer induced by abrupt velocity change of fluid flow is inevitable for nuclear power plant systems because of the sudden opening or closing of valves, the sudden startup or shutdown of the pumps and the rupture of pipes. The water hammer pressure wave can damage the pipes and cause the abnormal shutdown of Nuclear Power Plant (NPP). The object of this study is a Parallel Pumps Water Supply system (PPWS) adopted in a NPP. The PPWS is composed of two parallel mixed-flow pumps connected with a check valve separately, a container, a throttle flap and pipe lines. The Method of Characteristic line (MOC) was adopted to evaluate the water hammer behaviors of the PPWS during the alternate startup and shutoff conditions of two parallel pumps. A code was developed using Fortran language to compute the transient behaviors including he peak pressure, the flow velocity and the movement of the valve plate. The results indicate that the water hammer behaviors under low speed startup condition differ from that of high speed startup condition. The maximum pressure vibration amplitude is up to 5.0MPa occurring under high-high speed startup condition. The computation results are instructive for the optimization design of the PPWS so as to minimize the damage potential induced by water hammer.

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