ANALYSIS OF THE SBLOCA ON THE IMPROVED CPR1000 WITH PASSIVE SYSTEMS

摘要

As the development of the nuclear industry, passive technology turns out to be a remarkable characteristic in the design of advanced nuclear power plants. Since the 20th century, much effort has been given to the passive technology, and a number of evolutionary passive systems have developed. Even more interest is placed on the passive technology after Fukushima because of its independence on off-site power. In this paper, the CPR1000 plant, which is one kind of mature pressurized water plants in China, is improved with some passive systems to enhance safety. The passive systems selected are as follows: (1) the RMT (reactor makeup tank); (2) the A-ACC (advanced accumulators); (3) the IRWST (in-containment refueling water storage tank); (4) the PEFS (passive emergency feed water system), which is installed on the secondary side of SGs; (5) the PDS (passive depressurization system). These passive systems operate as a backup system for the original safety system of the CPR1000. Utilizing the RELAP5/MOD3.3 code, an analysis of SBLOCA (small-break loss-of-coolant accident) of this passive CPR1000 plant was presented to demonstrate whether the passive systems could mitigate the consequences caused by the accident. When the SBLOCA occurred, the RMTs were initiated to inject water into the pressure vessel. The low water level in the RMTs trigged the PDS, which depressurized the coolant system drastically. As the pressure of the coolant system decreased, the A-ACCs and the IRWST were put into work to prevent the core uncovery. The results show that, after the small-break loss-of-coolant accident, the passive systems can prevent the core uncovery and guarantee the safety of the plant.