[en] The Reactor Pressure Vessel (RPV) is the most critical component of pressurized water reactor. It has to comply with various rules and regulatory guides to ensure sufficient safety and operating margins during its lifetime including extended operation. Thus, it is crucial to assure the integrity of RPV for effective Plant Lifetime Management Program (PLIM). In this paper, the status and various issues on the integrity of the RPV of Kori Unit 1 are introduced. A circumferential weld in the beltline region was projected to be unable to satisfy the minimum upper shelf energy requirement and maximum reference temperature-pressurized thermal shock requirement before 40-year lifetime. The results of the detailed integrity analyses on both issues are summarized. As integral parts of PLiM Phase II Program of KEPCO, several actions have been taken as aging management programs to assure the integrity of Kori Unit 1 reactor pressure vessel, such as, redefining initial RT_NDT installing ex-vessel dosimetry, and withdrawal and testing of additional surveillance capsule. The applicability of these and other options including thermal annealing in current license period and during the extended operation are examined