Design Of Passive Residual Heat Removal System For Anvanced Reactor

One of the apparent characteristics of advanced PWR is inherent safety. One of the significant compositions of inherent safety is passive safety. The design of passive residual heat removal (PRHR) system for AP1000 reactor and a new design of secondary-side PRHR system is presented in this paper. The function of PRHR system is analyzed through simulation computation.Based on the prototype of AP1000 primary system and its design parameters, the RELAP5 models and nodalizations of primary system and PRHR system for AP1000 and secondary-side PRHR system are presented using RELAP5/MOD3.2. After a steady-state test of the program, the behaviors of PRHR system on normal operating conditions and operating transient proceeds are simulated to analyze the steady-state behaviors such as the ability of natural circulation, the stability of interface between cold and hot fluid in density lock for the PRHR system. The transient proceed of PRHR system during blackout accident is simulated to analyze the work capacity of the system in the accident.The factors affecting the capacity of PRHR system, such as the height between steam generator and PRHR heat exchanger, the local resistance of system circuit, the initial water temperature of in-containment refueling water storage tank and the heat transfer area of PRHR heat exchanger are estimated through changing the main design parameters of PRHR system. In addition, a comparative analysis of the two designs is given according to the results.The results show that core residual heat is able to be removed effectively, and the pressure and temperature of primary system are able to be reduced to assure the safety of reactor core using secondary-side PRHR system which is rationally designed during blackout accident. The design is good for its inherent safety, comparing with the primary-side design. The principal factors affecting the capacity of PRHR system are the height between steam generator and PRHR heat exchanger and the heat transfer area of PRHR heat exchanger, which produce an obvious effect on the natural circulation capacity of PRHR system.