A study on improvement of PHWR safety analysis methodology through LBLOCA assessment for Wolsong Unit 2

The assessment of the cooling capability of the emergency core cooling system (ECCS) in Wolsong Unit 2 for large loss of coolant accident (LLOCA), 35% break at the feeder pipe near the core entry, was performed to establish the safety regulation criteria for pressurized heavy water reactors (PHWRs). According to the results, the ECCS was estimated to be sufficient capability for LLOCA. However, the three dimensional power distribution in core should be considered in the safety analysis. Besides, it is also concluded that the determination of critical pass location and study of nuclear physics and thermal hydraulic characteristics in the critical pass during the accident should be also included in the safety analysis