Optimization and Analysis for Passive Residual Heat Removal System of an Integral Pressurized Water Reactor

Abstract

The characteristics of passive safety systems for an integral pressurized water reactor (IPWR) are quite different from the general reactor because of special configuration and dangerous run environment. Passive residual heat removal system (PRHRS) for the IPWR with three-interknited natural coolant circulation loops, safely remove the core decay heat to the ultimate heat sink. Using RELAP5/MOD3.4 code to simulate this system during the reactor trip, analyses the steady-state and transient-state thermohydraulic behaviors for the IPWR and its PRHRS, and the effects of design parameters on the system. it is found that on the initial period of reactor trip, due to the establishment of the natural circulation in three loops uncompleted, the secondary loop pressure have the peak value. Through analyzing the effects of design parameters on the system, the PRHRS are optimized. The results show that the larger the residual heat exchanger (RHE) heat transfer area and the higher the height difference between the steam generator and the residual heat exchanger, the easier the establishment of the natural circulation in the third loop, but which make the peak value of the secondary loop pressure higher. According to set the compensating water tank, which is parallel connected to the RHE, can lighten the higher the peak value of the secondary loop pressure, and optimize the design of PRHRS.