It is known that the seismic component damages have correlations. This degree of correlation is varied from zero to full dependence, depending on various situations, and there are so many correlations (one of every two components at a nuclear power plant has some correlations), that it is impossible to treat the correlation correctly. And the correlation factors are hard to be analyzed.

In this study, to confirm the sensitivity of the correlation of the seismic component damages to the PSA results such as Core Damage Frequency (CDF), assumptions from full dependence to zero dependence of the analytically selected components are introduced and the sensitivity analysis is performed.

This study shows that the CDF change is not more than twice but the impotence of seismic components are potentially sensitive. It is concluded that the CDF sensitivity for the correlation is not so high compared to the uncertainty of CDF in SPSA, but in the importance analysis, the correlation should be considered carefully.