Numerical Simulation Design Of Passive Emergency Injection Cooling System

Since the Fukushima nuclear accident,the safety protection system that relies on external energy or signal input has fully exposed its deficiencies.After that,the third-generation pressurized water reactor has begun to vigorously develop passive safety systems.The steam two-phase ejector does not require external energy input,and only relies on the deformation of the fluid itself and the contact heat exchange between the fluid and the steam to achieve pressure boosting and heating.It is a very reliable and efficient passive safety device.Therefore,based on the historical research of steam two-phase ejector and the safety concept of passive system,this paper proposes a passive emergency jet cooling system.After that,a passive emergency jet cooling system model was established,the design scheme was verified,and the influence of ejector working injection coefficient and structural parameters on system operation was discussed.The main research content and work of this paper are as follows:(1)The experimental data set of steam two-phase ejector was established,and the artificial neural network model of steam-jet pumped steam two-phase ejector was established using MATLAB software.After the model is established,it is compared with the prediction effect of the traditional one-dimensional flow model,which proves that the artificial neural network model has better prediction ability.Among them,the prediction effect of the artificial neural network trained using the Levenberg-Marquardt algorithm increased by 68%.(2)Based on Simulink simulation platform and Simscape module library,the steady state model of PWR dual circuit system is established.Compared with the stable operation value of PWR,the errors of the simulated values are less than 10%,which proves the feasibility of using Simulink simulation environment and Simscape module library to build the nuclear power system model.Moreover,the system model parameters of PWR dual-circuit system stable operation are obtained(3)The establishment of the main water supply pipeline rupture accident system model and the passive emergency jet cooling system model and the numerical simulation experiments verify the feasibility of the passive emergency jet cooling system model,and discuss the influence of the ejector’s working injection coefficient,the throat section ratio and the outlet section ratio on the system operation influences.Through the numerical simulation experiment,it is obtained that the working injection coefficient of the central steam jet type steam injector is 2.5 ～ 3.0,the throat section ratio is 1.1 ～ 1.3,and the outlet section ratio is 0.5 ～ 2.0,which can ensure the stable operation of the system.