Study on long-term cooling and boron concentration characteristics in case of cold leg large break LOCA accident

The flow heat transfer and boron concentration characteristics in the upper plenum and the core affected by CCFL during the phase of simultaneous hot and cold leg injection in case of cold leg large break LOCA for the ACP1000 NPP were studied using the advanced T-H code CATHARE, and the effects of the safety injection flowrate from the hot leg located in broken loop on the core cooling was also studied in the paper. The study showed that the core cooling would not be mostly affected by the hot leg flowrate in the broken loop if the total hot leg injection flowrate fixed at 614 m³/h, and the boron concentration in the core would balance with the system after switching to simultaneous hot and cold leg injection. (authors)