| In recent years,China's nuclear power plant construction is developing rapidly.The most critical and top factor in the construction and operation of nuclear power plants is safety.Ensuring the overall safety of nuclear power plants is the basis for the effective use of nuclear energy.The nuclear power plant auxiliary water supply system is a special safety facility that supplies water to the secondary side of the steam generator to maintain its water level when the main water supply system is lost.To realize the diversification of the power system,the system is equipped with an electric pump and a steam pump.When the system is put into operation,even if the electric pump cannot be started due to power failure,etc.,the steam pump can ensure the system operation by using the main steam as the power.Therefore,the steam pump is the core equipment to ensure the auxiliary water supply when the water supply is put into operation,especially in the case of power failure.Auxiliary feed pumps have multiple failure modes during commissioning and operation after operation,delaying the start and stop of critical paths.Common failure modes include performance deviation of the speed control mechanism of the steam pump,abnormal water pressure on the water pump,and excessive speed increase of the steam pump.203 overhaul of Domestic H Nuclear Power Plant,the steam pump(2ASG004PO)tripped during the test during the start of the unit.Through the RCA root cause analysis and the experience measures of the overhaul process in the past,the throttle plug is added to the exhaust steam solenoid valve(2ASG237/238VV)to extend the valve opening time.The test results were re-executed,and the pump jump phenomenon did not occur after four tests.For the electromagnetic overspeed trip event of 2ASG004 PO steam pump,this paper is based on auxiliary water supply system;equipment function and structure;steam pump speed,pneumatic control valve opening time,steam pump flow,steam pump head and other parameters historical data.To analyze the failure mode of the electromagnetic overspeed trip of the steam pump.In this paper,the RCA root cause analysis method is used to systematically analyze the fault modes such as the performance deviation of the steam pump governing mechanism,the abnormal pressure on the water side of the steam pump,and the rising speed of the steam pump.The UG software is used to establish the 3D model,the flow field analysis is performed by ANSYS-CFX software,and the impeller hydraulic model is finally obtained.At the same time,the transient simulation model of the ASG system is established,and the simulation analysis and comprehensive simulation analysis of the pump transient are carried out,and the final determination is made through demonstration.The most likely reason.Through the development of the research content and the analysis of the fault model,the reason for the electromagnetic overspeed trip of the 2ASG004 PO steam pump is as follows: on the one hand,the speed of the steam pump is high,due to the inherent liquid in the pump.In response to the hysteresis characteristic,the water side pressure is established slowly,which causes the speeding mechanism to have insufficient driving force to cause overspeed.On the other hand,the steam pump is provided with the steam isolation valve opening characteristic,the valve response response characteristic and the inherent response hysteresis characteristic of the pump liquid.Poor match.There is also a large loss of the inlet pipe resistance of the even-numbered unit No.4 pump and a poor cavitation performance of 2ASG004 PO.Based on the research on the root cause of the electromagnetic tripping problem of ASG steam pump,this paper uses the RCA root cause analysis method to determine the root cause of the electromagnetic trip of the steam pump by means of modeling and simulation analysis software,and proposes corresponding corrective measures to solve the problem.Equipment common mode problems,but also other equipment failure analysis provides reference. |
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