[en] In this study, the most uncertain input parameter in the PSHA was identified for Korean NPP sites through sensitivity analysis. Shinuljin Nuclear Units 1 and 2 site was selected in this study. Expert panels developed input parameters for PSHA. Input data were analyzed, and used for sensitivity analysis to see the effects of each parameter on seismic hazard. Through sensitivity analysis, we identified the degree of uncertainty of each parameter. The CONPAS, EQHAZAS, and EQHAZAS Manager codes, which were developed by KAERI, were utilized to compute the seismic hazard. The Gutenberg-Richter parameter was identified as the most uncertain one in this study