Maafi Israe ENC: Mechhoud El-Arkam2026-02-222026-02-222025-11-10http://dspace.univ-skikda.dz:4000/handle/123456789/5884Industrial safety is a crucial issue in high-risk fields like the petrochemical sector, where the complexity and the combination of advanced control systems, software, and human elements pose challenges to traditional risk assessment techniques. This thesis investigates the shortcomings of standard methods such as HAZOP, FMEA, and QRA, which frequently do not adequately address the dynamic interactions and systemic factors that lead to accidents in contemporary industrial settings. To overcome these limitations, the research delves into the use of System-Theoretic Process Analysis (STPA), a contemporary safety analysis approach based on systems theory. Created by Professor Nancy Leveson, STPA views safety as a control challenge rather than simply a matter of reliability. The thesis applies STPA to Reactor 950- 155 at CP2K-Sonatrach Skikda, following its four primary steps and utilizing ALOHA for simulation purposes.enThesis