Enhanced safety characteristics of SMART100 adopting passive safety systems

Abstract

SMART100 is a small sized integral type pressurized water reactor (PWR) with a rated thermal power of (Chung et al., 2015) 365 MW, which adopts various inherent and passive design features to enhance safety. Most of the primary circuit components, such as the core, reactor coolant pumps, steam generators, and a steam pressurizer are contained in a single leak-tight reactor pressure vessel. Due to the integral reactor design, the large pipes connecting the major components are removed. Thus, the possibility of a large break loss of coolant accident (LBLOCA) is inherently eliminated and the natural circulation capability is improved during the transient. Also, SMART100 has inherent design characteristics of the large primary coolant inventory per unit thermal power, low core power density, and increased secondary system design pressure. Due to these design characteristics, SMART100 can enhance the mitigation capability to a wide range of initiating events. In addition to these inherent safety design features, the safety goals of SMART100 are enhanced by the passive safety systems such as the passive residual heat removal system (PRHRS) (Bae et al., 2001) and passive safety injection system (PSIS). To confirm the enhanced safety of SMART100, deterministic safety analyses were performed for the safety related design basis events (SRDBEs). The results of the analyses using an evaluation model of the TASS/SMR-S code and conservative initial/boundary conditions and assumptions show that the acceptance criteria for the fuel integrity, system integrity, and radiation doses specified in the safety review guidelines are well met. Therefore, the passive safety systems of SMART100 adequately mitigate the consequences of all SRDBEs and maintain the plant in a safe shutdown condition without any AC power or operator action for at least 72 h.