Passive safety systems and heat pipe applications in nuclear power plants

Abstract Passive safety systems are now one of the fundamentals in designing advanced nuclear power plants, for enhancing safety and reliability by utilizing natural phenomena like condensation, natural circulation, gravity, and compressed air instead of active mechanical parts. This paper provides a thorough review of passive safety features in modern reactor designs, such as the AP1000, APR+, CPR1000, and different small modular reactors (SMRs). Particularly focuses on integrating heat pipe technology as a passive solution for decay and residual heat removal and reactor core cooling. The analysis focused on the design and operational performance of these systems. This study showed that different alternatives of passive safety features with advanced heat pipe applications can improve safety and thermal management in future nuclear power plants. This work presents a comprehensive review of passive safety systems and heat pipe applications in nuclear power plants, integrating foundational research from early passive reactor concepts with recent state-of-the-art studies published from 2022 to 2025.