The Improvement and Validation of Setpoint Methodology for Diverse Protection System

摘要

The trip setpoint methodology for the Diverse Protection System (DPS) has been improved to prevent the Advanced Power Reactor 1400 (APR1400) nuclear power plants in Korea from occurring spurious trips. To avoid a plausible earlier actuation of DPS prior to the Plant Protection System (PPS), the DPS trip setpoint is required to have a sufficient margin from the PPS trip setpoint. In addition, the DPS trip setpoint determined by the methodology proposed herein is required to have a proper allowable value defined as a limiting value that the trip setpoint may have when the DPS is tested periodically. This paper presents the quantitative calculation results of the trip setpoint and allowable value for APR1400 DPS using the conventional setpoint methodology. The validation results of the proposed setpoint methodology using nuclear safety analysis computer codes are also provided herewith. The results confirm that the proposed setpoint methodology enables a determination of the DPS trip setpoint which prevents unnecessary reactor trips. It is also verified that the proposed setpoint methodology is suitable for determining a proper allowable value to limit the variation of the DPS trip setpoint.