Method to improve seismic performance: Selection of key components and multi-objective optimization of risk and cost

Considering the increasing frequency of large-scale earthquakes worldwide, ensuring the seismic safety of nuclear power plants against earthquakes exceeding the design conditions is essential. Therefore, this study proposed a method for enhancing seismic performance using a seismic probabilistic safety assessment-based risk model. Sensitivity analysis and a multi-objective grey wolf optimizer, which is a multi-objective optimization method, were utilized for seismic performance enhancement. First, a sensitivity analysis was conducted to identify the key components that significantly affected seismic performance. Subsequently, optimization techniques were employed to maximize seismic performance with minimal reinforcement costs. The proposed method was applied to risk models of nuclear power plants and research reactors. The application results showed that the key components from the sensitivity analysis exerted the greatest impact on the enhancement of the seismic performance. In addition, Pareto optimal solutions for seismic reinforcement cost and performance improvement were obtained through optimization. Because Pareto optimal solutions represent various optimal solution sets for seismic reinforcement cost and performance improvement, they are considered as appropriate guides for the achievement of the desired level of seismic performance improvement at minimum cost. The proposed method can help improve the seismic performance of existing nuclear power plants against earthquakes that exceed the design conditions.