Study on Mitigating Capability of AFW System for SBO Accident

The transient characteristic of the simplified system for CPR1000 under the station blackout (SBO) accident was simulated by use of RELAP5/MOD3.2 code, and the capability of mitigating accident results after auxiliary feedwater (AFW) system operating was also analyzed. The calculation results show that: As a result of the loss of the main water supply, the average temperature and the pressure of the primary system reach their maximum in 6 s after SBO accident; the increasing of temperature and pressure caused by the loss of heat sink is effectively mitigated in about 200 s after the input of auxiliary feed water, and this will win more time for the recovery of AC power and the input of residual heat removal system.