Safety assessment of AP1000: Common transients, analysis codes and research gaps

The commercial operation of the AP1000 in China’s Sanmen nuclear power plant demonstrates the feasibility of reactors with advanced passive safety systems. However, being the first-of-a-kind, there is a need for robust, diverse, and independent safety assessment of the plant’s components and systems. This study presents a critical review of AP1000 transients, categorizes and evaluates current safety assessment codes, and discusses their application to safety analysis of AP1000. We extensively discuss the AP1000 safety assessment methods and enumerate sources of uncertainties in codes that have been used to assess a wide spectrum of AP1000 transients. In addition, we identified basic developmental issues in different system codes and crucial problems with their applications to AP1000. Furthermore, we give insights into optimized simulation techniques and advanced modeling approaches for high fidelity computation. As unique contributions, key issues such as the reliability of the passive safety systems, scaling, verification and validation experiments necessary to enhance the safety of AP1000 are discussed. The significant research gaps, future research direction, and current safety issues presented in this work also serve as an important body of knowledge towards a safe and reliable operation of future AP1000 fleets.