Zennir YoucefMechhoud El-Arkam2024-05-072024-05-072024-04-26DOI: 10.18280/ijsse.140205http://dspace.univ-skikda.dz:4000/handle/123456789/1607Hazard analysis and risk assessment are critical for ensuring safety and reliability in complex systems. This article presents a combined approach to hazard analysis and risk assessment using Functional Block Diagrams (FBD) and Systems-Theoretic Process Analysis (STPA) methods. The FBD method is a versatile and intuitive diagrammatic technique used to describe the functions and interrelationships of complex systems. It represents the system as a set of interconnected blocks, each depicting a specific function, which collectively defines the system's behaviour. On the other hand, STPA is an advanced safety analysis method focusing on control structures and the interaction between components. It identifies potential unsafe control actions by analysing the information flow and the system's feedback mechanisms. The two methods are complementary and can be integrated to provide a more effective and efficient approach to hazard analysis and risk assessment. A case study of a nuclear power plant is used to demonstrate the benefits of the combined approach. Practical considerations for implementing the approach are discussed and compared with other hazard analysis and risk assessment methods. The article concludes with suggestions for future research and development in this area, highlighting the potential impact of the combined FBD-STPA approach for improving safety and reliability in complex systemsenArticle