Application of System-Theoretic Process Analysis to Engineered Safety Features-Component Control System

Recent developments in safety-critical systems have heightened the need for hazard analysis because results of their accidents have become more and more serious. Traditional hazard analysis techniques, such as fault tree analysis (FTA) or failure mode and effects analysis (FMEA), have been extensively used for decades. However, traditional techniques are not suitable for modern systems which are more complex, software-intensive, socio-technical systems. SystemTheoretic Process Analysis (STPA) is a new hazard analysis technique based on System-Theoretic Accident Model and Processes (STAMP) which is a new causality model developed by Nancy G. Leveson. It aims at identifying accident scenarios that encompass the entire accident process. This paper introduces application of the STPA to Engineered Safety Features-Component Control System (ESF-CCS) which prevents radiation leakage from a nuclear reactor. The application performed three functions of the ESF-CCS which has 8 functions. Results of this research show that analysts have a different view about causes of accidents. Furthermore, the view lets the analysts focus on identifying different causal factors from what other hazard analysis techniques identify.