Exploring Loss Scenarios of STPA with Reinforcement Learning: A Case Study of Platform Screen Door

System-Theoretic Process Analysis (STPA) is performing a potential hazard analysis in the interactions of components within a system. Among STPA's process, deriving loss scenarios by identifying causes of the hazard has become increasingly important due to the complexity of modern systems. In this study, we utilize reinforcement learning to derive state transition paths that lead to hazard as loss scenarios, and extract the frequency of risk frequencies to demonstrate the necessity of safety measures for the respective loss scenarios. It is anticipated that this efficient approach will aid in simulating the system design process and enhancing safety.