Development of integrated response time evaluation methodology for the plant protection system

Safety analysis for a nuclear power plant establishes not only an analytical limit in terms of a measured or calculated variable but also an analytical response time required to complete protective action after the analytical limit is reached. If the two constraints are met, the safety limit selected to maintain the integrity of physical barriers used for preventing uncontrolled radioactivity release will not be exceeded during anticipated operational occurrences and postulated accidents. Setpoint determination methodologies have been actively developed to ensure that protective action is initiated before the process conditions reach the analytical limit. However, regarding the analytical response time for the plant protection system (PPS), an integrated evaluation methodology considering the whole design process has not been systematically studied. In order to assure the safety of nuclear power plants, this paper proposes a systematic and integrated response time evaluation methodology that covers safety analyses, system designs, response time analyses, and response time tests. This methodology is applied to the PPS for the advanced power reactor 1400 nuclear power plant in Korea. The quantitative evaluation results are provided herein. The evaluation results using the proposed methodology demonstrate that the PPS completely satisfies the requirement of the analytical response time.