Study On The Method Of Realizing The Initial Test Condition Of The Integral Effect Test Of Station Blackout Accident

The Integral Test Facility(ITF)is generally used for the study of the overall performance of the power plant system under the Station Blackout(SBO)accident.Due to the limitations of its structure and operating parameters,the test device cannot contain the entire thermal parameters of the prototype nuclear power plant.Therefore,in the research process,it is necessary to specifically demonstrate the selection of the initial conditions of the test,and formulate corresponding experimental conditions for the initial conditions of the test.In view of the initial conditions of the whole plant power failure overall effect experiment,this paper uses the natural circulation test device and RELAP5 system analysis code to carry out the research on the initial conditions of the whole plant power failure test.According to the structure and operating parameters of the existing natural circulation test facility,Established the model of RELAP5 numerical simulation.Based on the SBO accident process and characteristics of the nuclear power plant,set up the corresponding control logic.In order to ensure the rationality of the number of model nodes,the sensitivity analysis of different quantity of node number was carried out,and the final node division of the natural circulation test device was determined.In order to verify the accuracy and reliability of the RELAP5 model,comparing the calculate and experiment results.Based on the validated RELAP5 model,the power integration and state parameter fitting were used to study the realization process of the initial conditions of the SBO accident test.The parameters such as system circulation flowrate,coolant temperature and system pressure were obtained under the different methods.For the initial condition selection in the state parameter fitting method,the sensitivity analysis of the initial point selection time is carried out;combined with the process of the two experimental initial conditions,the variation characteristics of the system parameters after the initial point are compared and analyzed,The main loop parameters obtained by the two initial conditions are basically consistent with time,but the values of the parameters are different.The test results are not only related to the initial point of the test,but also related to the characteristics of the transition phase before the initial point of the test.Since the change of the parameters of the primary loop system is a continuous change process,the thermal hydraulic state before the initial point directly affects the system parameters after the initial point.Development;when the initial conditions are implemented by the state parameter fitting method,the different initial point moments have little influence on the change trend of the system parameters in the test;the transient effect of the system parameters in the power split method is more obvious,and the calculation results show the corresponding The thermal hydraulic parameters of the system are higher than the parameter fitting method;The influence of the initial point selection position of the integrated power method is larger than parameter fitting method.