Traditional text-based system engineering in the design and application of passive residual heat removal systems (PRHRS) for lead-cooled fast reactors has several requirement problems, such as low development efficiency, a long iteration cycle, and model ambiguity.

This study aims to effectively address the aforementioned problems encountered in the PRHRS of lead-cooled fast reactors by adopting a model-based system engineering method.

The model-based system engineering (MBSE) method was preliminarily applied to the design requirement analysis of a PRHRS for lead-cooled fast reactors. During the design requirements study, the design process was combined with the preliminary design of the system architecture, comprising three parts: requirements analysis, functional analysis, and design synthesis.

The generated requirement and use case diagrams describe the system requirements and determine the top-level use cases of the system in the requirement analysis stage. The time sequence, activity, and state machine diagrams form the system function model and provide early confirmation and verification in the functional analysis stage. Finally, the white box model realizes the analysis and design of the system architecture in the design synthesis stage.

The system architecture designed by this method ensures the consistency of the design requirements. In the future, it will further reduce the design risk, improve the design efficiency, and provide an application reference for the design and optimization of digital lead-cooled fast reactors' passive residual heat removal systems.