Development strategy of optimized Level 1&2 PSA model for APR1400 NPPs reflecting new severe accident mitigating system and its application

Since the Fukushima nuclear accident, various efforts to improve safety have been undertaken for nuclear power plants all over the world, such as the implementation of new measures to cope with severe accidents and the application of PSAs in SAMG. In the case of the domestic probabilistic safety assessment (PSA), the regulatory body is strengthening the safety goals of operating and constructing nuclear power plants through the accident management plan, including the safety objectives recommended by the USNRC. This new safety goal calls for a more realistic reflection of the "as-built, as-operated" status of nuclear power plants as well safety enhancement of nuclear power plants during operation. In this paper, we propose a practical methodology for developing a Level 1 & 2 PSA model that reflects the inherent characteristics of Korea and conforms to the new safety goals recommended by domestic regulatory agencies. To this end, we benchmarked a recent State of the Art Reactor Consequence Analysis (SOARCA) study in the United States. The selection of scenarios reflecting the inherent characteristics of Korea, the application strategies for severe accident mitigation equipment and SAMG to PSA model and revision of the Level 1 & 2 PSA model for selected scenarios are presented. The results of this study can be applied to the PSA model update conforming to the new safety goals, the revision of the Level 1 & 2 PSA reflecting the unique characteristics, and analysis of the actual radiation source term and Public Acceptance.