[en] Post 911, in the U.S., the budget relate to security was rapidly increased, and U.S. NRC (Nuclear Regulatory Commission) requires to evaluate the security at the new nuclear power plant design. Moreover, actions strengthening security are adopted to defense terror such as the security relation department is established newly in the IAEA (International Atomic Energy Agency), etc. NUREG-1860 defines the goals and expectations for safety, security, and preparedness required at future plants licensed by the NRC. Since safety, security and preparedness to achieve the overall level of safety for the safety of future plants are necessary; Vital Area Identification (VAI) technology on the nuclear facilities has been required. Korea prepared the legal and the systematic foundation by establishing and effectuating 'A law of a protection and radioactivity disaster prevention measures' for nuclear facilities, etc. in February 2004 by reflecting INFCRC/274/Rev. 1[8] and INFCRC/225/Rev. 4. However, U.S. owns most physical protection technologies, and most of them are classified as the secret for the prevention of terror. Therefore, the development of vital area identification method considering the domestic actual conditions is necessary. This report provides with a process which can be used as a base for vital area identification (VAI), and helps to understand VAI of beginners and managers of a licensee and regulatory body through the description for the Top Event Prevention Sets (TEPS) evaluation process based on Probabilistic Safety Assessment (PSA) the vital area priority determination. The result of the VAI selects the cost-effective TEPS from many candidate TEPSs. However, the systematic procedure to determine TEPS priority has not been provided. Therefore, in the report, we provide the description about the whole process for the TEPS selection, a qualitative evaluation method required for the prioritization of TEPS drawn through the code task, and high-level procedure