This study develops a regulatory framework for Multi-Unit Probabilistic Safety Assessment (MUPSA) to enhance nuclear safety in South Korea, where multiple reactors are concentrated at single sites.
Since 2017, research has focused on integrating policy and technical elements, including safety objectives, regulatory guidelines, and advanced PSA methodologies.
The framework extends single-unit PSA to multi-unit conditions by considering shared systems, physical dependencies, and common-cause failures, along with external hazards such as earthquakes, tsunamis and wild fires accidents.
Quantitative results show that multi-unit contributions from internal events are limited, while seismic events dominate multi-unit risk; however, total site risk remains within existing safety targets.
The proposed framework supports regulatory applications such as safety verification and risk-informed decision-making for multi-unit nuclear sites.