Wildfire risk assessment of nuclear power plant off-site power systems using human-activity–informed localized inputs: A case study of the Kori nuclear power plant

Wildfire represents a significant natural hazard with the potential to disrupt the off-site power system (OPS) of nuclear power plants (NPPs). Their frequency and intensity are expected to increase due to climate change. The loss of OPS resulting from wildfires can critically affect the safety and operational stability of NPPs, highlighting the need for comprehensive risk assessment. This study compares the results of wildfire risk assessments based on conventional, generalized input data derived from regional statistics with those based on detailed data that incorporate human activity characteristics to improve assessment precision. The proposed methodology is applied to the Kori NPP site, considering the wildfire occurrence frequency at the local administrative level, adjustments based on site accessibility, and regional statistics on wildfire duration. Findings from the Kori NPP case study indicate that incorporating these detailed factors can substantially change the estimated annual probability of loss of the OPS; in this case study, the estimate decreased by up to 95% relative to the baseline. Among all factors, regional variation in wildfire frequency was identified as the most influential parameter. This finding emphasizes the importance of spatially specific input data in enhancing the reliability of wildfire risk assessments. The proposed approach helps avoid both overestimation and underestimation of risk, offering practical insights for developing operational strategies and safety policies for NPPs through localized and accurate analysis.