Probabilistic safety assessment methodology for loss of off-site power system due to wildfires

Wildfires are combustion phenomena involving flammable forest materials, leading to significant ecological and social losses. Climate change is expected to intensify wildfire risks by reducing relative humidity and increasing maximum temperatures. In addition to environmental damage, wildfires pose threats to critical infrastructure, including nuclear power plants (NPPs) and off-site power systems. Notably, the Hanul NPP experienced wildfire-related disruptions in 2000 and 2022, while the Oyster Creek NPP (1992) and Diablo Canyon NPP (2001) also encountered operational impacts due to wildfires. These incidents have prompted various studies on safety assessments of power system failures caused by wildfires. This study presents a methodology for estimating the probability of loss of off-site power (LOOP) due to wildfires. The proposed method derives the probability using Monte Carlo Simulation (MCS) based on burn probability data from a wildfire hazard map. The methodology is applied to the Hanul NPP to evaluate the wildfire-induced LOOP probability. The proposed methodology is expected to contribute to improved wildfire preparedness and enhanced NPP safety.