A preliminary conceptual design has been performed to develop a 2-loop 1,000 MWe passive pressurized water reactor, which is expected to be the suitable type for the next generation reactor in Korea, by incorporating the passive safety features into the reactor coolant system based on Korean Standard Nuclear Power Plant. Preliminary design parameters have been determined through simple bounding calculations and engineering judgment for reactor, reactor coolant system, passive safety injection system, and passive residual heat removal system. The performance of the designed safety systems has been assured through the analysis of a double ended guillotine break LOCA. A system analysis code, RELAP5/MOD3, has been used and one of the direct vessel injection lines has been assumed to be broken. And the sensitivity studies have been performed with various sizes of automatic depressurization valve and of direct vessel injection line diameter. This thesis presents the developmental strategy, preliminary design parameters and associated calculational procedures and safety analysis results.