Reliability Assessment of Reactor AP1000 Passive ERVC System

As the safety requirements level of nuclear power plant is gradually improving, more and more passive systems are used in the advanced type reactors. However, the reliability evaluation work for these passive systems is still in the primary stage. Therefore, in this paper the work is started based on the reliability evaluation process of passive system, simulates the physical process of passive systems by RELAP thermal hydraulics program, and evaluates the reliability of AP1000 External Reactor Vessel Cooling (ERVC) system. After the large number of calculations the cumulative density distribution curve of the temperature in lower head of the reactor pressure vessel is obtained, so by combining with specific success criteria the reliability of AP1000 ERVC system can be obtained, and this reliability evaluation result of ERVC system can be used in the PSA model to better guide the design of nuclear power plants and improve the safety of nuclear power plants.