While Modelica has become a standard for multi-domain modeling in various complex engineering fields, professional and systematic model libraries specifically tailored for the nuclear power sector remain scarce. To bridge this gap, this paper presents the development of a specialized Modelica fluid component library for Small Modular Reactor (SMR) systems. Serving as a critical module within the broader CGN_NHR library, this framework bridges the gap between fundamental fluid mechanisms, equipment-level modeling, and system-level assembly. We detail the library’s architecture, design philosophy, and the mathematical formulation of its core components. To verify its validity and reliability, a systemlevel model was constructed and benchmarked against the industry-standard RELAP5 model. Comparative results confirm that the proposed library offers high efficiency and accuracy, establishing a robust technical foundation for the rapid design, simulation, and verification of nuclear power systems.

As the pivotal equipment connecting the primary and secondary loops of pressurized water reactor nuclear power plants, the dynamic thermo-hydraulic characteristics of the nuclear steam generator are directly related to the safe and stable operation of the unit. However, traditional modeling approaches suffer from poor versatility and low efficiency, making it difficult to meet the R&D demands for diverse application scenarios and iterative optimization. Addressing these bottlenecks, this paper proposes a modular modeling and dynamic simulation method for nuclear steam generators based on the Modelica language. First, based on a hierarchical modeling approach, component-level models covering plena, pipes, heat structures, steam-water separators, and feedwater plena are constructed to achieve free configuration and visual simulation modeling. Second, according to the operating principles and structure of the nuclear steam generator, a complete dynamic simulation model is assembled using these component-level models. Finally, the established model is validated against the RELAP5 code to verify the effectiveness and reliability of the proposed method. The results indicate that the Modelica-based steam generator simulation model combines high accuracy with high efficiency, providing significant technical support for the rapid design and verification of nuclear power systems.

Nuclear power systems are complex multi-disciplinary systems involving thermal hydraulics, fluid mechanics, control engineering and electrical engineering. Comprehensive performance analysis and optimization of such systems require coupled multi-disciplinary modeling and simulation. Nevertheless, co-simulation via interfaces between separate single-discipline simulation software brings numerous inherent drawbacks. Hualong One is China’s domestically developed third-generation pressurized water reactor. To accelerate system modeling and simulation efficiency, this paper independently develops the unified multi-disciplinary modeling library CGN_HPR V1.0 based on Modelica and the hierarchical modeling method, with the domestic MWorks simulation platform as the core development environment. Adopting a four-tier architecture consisting of basic, component, equipment and system levels, the library supports modular, parameterized and visual modeling for streamlined simulation analysis, and addresses the technical bottleneck of insufficient deep coupling in traditional multi-disciplinary simulation workflows. Typical operating conditions of Hualong One are modeled and simulated using the proposed library, which preliminarily verifies the validity of the Modelica-based system simulation model. The results demonstrate that the Modelica-enabled simulation framework enables seamless integration of cross-disciplinary subsystems, mitigates the difficulties in multi-disciplinary coupled simulation for nuclear power plants, and improves overall system analysis and design capacity, providing key technical support for unit safety assessment and operational optimization.

Integrated energy-system models become difficult to reuse when electrical signals, thermal-fluid states, supervisory logic, and evaluation variables are coupled through inconsistent interfaces. This paper presents an OpenModelica platform with unit-explicit cross-domain connectors, graphically encapsulated component models, and a reusable library for renewable generation, conversion, and storage. The thermal loop employs Modelica.Fluid ports and a temperature-dependent SolarSalt medium, while the wind and photovoltaic components expose available, delivered, and curtailed power to support source-level curtailment feedback from the energy-management system. A DASSL-based workflow is applied to a full-year Dunhuang case and complementary parameter-variation cases. The annual simulation maintains complete park electric-load supply, achieves a heat-load satisfaction rate of 90.16%, and yields an electric LCOE of 0.307 CNY/kWh. Statevariable and sensitivity analyses indicate that renewablesource and battery sizing govern electrical absorption and economics, whereas winter thermal-storage availability and heat-side capacity constrain thermal reliability. The platform therefore links reusable Modelica implementation with long-horizon system evaluation without requiring topology-specific reformulation.