Hydraulic Characteristics And Stress Check Of The Main And Auxiliary Steam System Network Of Nuclear Power Secondary Circuit

The secondary circuit system,which is an important part of the nuclear power plant.The secondary circuit pipe network system is used as the structure for transporting the working medium between each equipment,its distribution characteristics are related to the stable operation of each steam equipment.The secondary circuit pipe network system has many branches,the flow in the pipe is large,and the working conditions of the nuclear power plant is complicated,so the change of a parameter will influence the flow distribution characteristics of the entire pipe network system.The stress concentration is easily produced and threat the safety of pipeline due to the complicated arrangement of the pipeline.Therefore,studying the hydraulic characteristics and stress characteristics of the two-circuit pipe network system is important for the design and operation of the whole system.In this paper,the main-pipe network of the nuclear power secondary circuit system is taken as the research object.Firstly,the principle experiment table is built according to actual structure,and the steady state experiment was finished for exploring the variation of flow and pressure of each pipeline under different conditions.Secondly,based on accident conditions that may occur in the actual system,the dynamic experiments were finished to analyze the variation law of flow and pressure in each case.Thirdly,the Flowmaster was used to model the actual system,and the dynamic simulation to the distribution characteristics of pipe network system were finished under accident conditions.Finally,the CAESARII was used to check the pipe stress from the steam generator to the main pipe under each working conditions.The rationality of the pipeline layout is verified and an optimization plan is proposed.The results show that the flow distribution law of the pipe network obtained by the simulation is verified by the experiment results;In the simulation of steam leakage accident,the steam in main steam turbine pipeline and the low pressure steam generator pipeline are first appear insufficient with the increase of the steam leakage,and the regulating valves has less and less effect to the flow and pressure of each pipeline with the increase of steam leakage;In the simulation of the No.1 main turbine trip,with the control of the regulating valve of each steam equipment the flow and pressure can be effectively stabilized;In the simulation of a reactor loss,the regulating valve has very little control effect to the flow and pressure of each pipeline;Under static conditions,the stress from the steam generator to the main pipe is within the allowable stress,but the stress exceeds the standard under the dynamic conditions of the safety valve exhaust,through the optimization of the pipeline structure,the stress is qualified under the working condition.