The current load combination criteria for design of nuclear power plant structures(NPP) are not based on the probability • based design concept but rely on the conventional design concept. ln this paper. a load combination criteria for design of NPP containment structures are proposed based on a FEM - based random vibration analysis. More accurate reliability analyses under various dynamic loads such as earthquake loads were made possible by incorporating the FEM and random vibration theory‘ which is different from the conventional reliability analysis method. ln this paper‘ the load factors for the design of NPP structures in Korea are pro∞sed by considering appropriate load combination criteria for design