Seismic response correlation coefficient for the structures, systems and components of the Korean nuclear power plant for seismic probabilistic safety assessment

•The seismic safety of NPPs is evaluated through SPSAs•Most SPSAs are based on an independent condition or fully dependent condition of SSCs•A seismic response correlation coefficient between SSCs is needed for reasonable SPSA•A seismic response correlation coefficient between SSCs for the nuclear power plant is suggested The seismic probabilistic safety assessments of nuclear power plants (NPPs) conservatively assume that the correlation between the seismic failure to structures, systems, and components (SSCs) is independent or fully dependent. This, however, is an extreme assumption, and so a more appropriate seismic failure correlation should be considered for accurate safety assessments. Quantification of the correlation of seismic failure can be expressed with a correlation coefficient; to calculate this, correlation coefficients for both seismic response and seismic performance between SSCs are required. This study suggests a seismic response correlation coefficient for the OPR1000 Korean NPPs. To this end, a probabilistic seismic response analysis was performed considering the randomness and uncertainty of earthquakes and structures. Based on this in-structure spectrum, the seismic response correlation coefficient between the SSCs was derived and databased. Seismic response correlation coefficient values are also suggested that can easily be applied to auxiliary buildings of NPPs.