This study investigates the risk reduction effect and identifies the optimal capacity of Multi-barrier Accident Coping Strategy (MACST) facilities for nuclear power plants (NPPs) under seismic hazard. The efficacy of MACST facilities in OPR1000 and APR1400 NPP systems is evaluated by utilizing the Improved Direct Quantification of Fault Tree with Monte Carlo Simulation (I-DQFM) method. The analysis encompasses a parametric study of the seismic capacity of two MACST facilities: the 1.0 MW large-capacity mobile generator and the mobile low-pressure pump. The results demonstrate that the optimal seismic capacity of MACST facilities for both NPP systems is 1.5g, which markedly reduces the probability of core damage. In particular, the core damage risk is reduced by approximately 23% for the OPR1000 system, with the core damage fragility reduced by approximately 72% at 1.0g seismic intensity. For the APR1400 system, the implementation of MACST is observed to reduce the core damage risk by approximately 17% and the core damage fragility by approximately 44% under the same conditions. These results emphasize the significance of integrating MACST facilities to enhance the resilience and safety of NPPs against seismic hazard scenarios, highlighting the necessity for continuous adaptation of safety strategies to address evolving natural threats.

A B S T R A C T
1. 서 론
2. 리스크 평가 방법 및 재해 시나리오
    2.1 I-DQFM 방법을 통한 지진 리스크 정량화
    2.2 지진 재해 시나리오 및 최적 성능 도출을 위한 실험 방법
3. 대상 원전 시스템
    3.1 MACST 설비를 고려한 대상 원전의 사건 수목
    3.2 대상 원전 시스템 구성 요소의 지진 취약도 정보
    3.3 지진 재해에 대한 원전 시스템 구성 요소의 상관행렬
4. 지진 리스크 평가 결과 및 최적 내진 성능 제안
    4.1 OPR1000에 대한 리스크 평가 결과 및 최적 내진 성능
    4.2 APR1400에 대한 리스크 평가 결과 및 최적 내진 성능
5. 결 론
감사의 글
REFERENCES

• 김민규(한국원자력연구원 구조, 지진안전연구부 박사후연구원) | Kim Minkyu (Postdoctoral Researcher, Structural and Seismic Safety Research Division, Korea Atomic Energy Research Institute)
• 최유정(한국원자력연구원 구조, 지진안전연구부 선임연구원) | Choi Eujeong (Senior Researcher, Structural and Seismic Safety Research Division, Korea Atomic Energy Research Institute) Corresponding author
• 장승현(한국원자력연구원 구조, 지진안전연구부 박사후연구원) | Jang Seunghyun (Postdoctoral Researcher, Structural and Seismic Safety Research Division, Korea Atomic Energy Research Institute)
• 함대기(한국원자력연구원 구조, 지진안전연구부 책임연구원) | Hahm Daegi (Principal Researcher, Structural and Seismic Safety Research Division, Korea Atomic Energy Research Institute)