Analysis With Different Containment Models for Containment Response of NHR200II Under Loss‐of‐Coolant Accident

In the design of nuclear power plant systems, the thermal–hydraulic response in the containment during a loss‐of‐coolant accident (LOCA) plays a crucial role. In this study, the advanced small modular reactor NHR200‐II is selected as the research object. The transient responses of the containment during a typical small break LOCA (SBLOCA) with different containment models are modeled and compared, including both the lumped parameter approach with a single volume and the distributed parameter approach with subdivided volumes. The analysis results revealed that the containment pressure responses—a key thermal–hydraulic parameter during SBLOCA transients in the NHR200‐II design—show only minor differences when modeled using the two approaches. These findings indicate that the lumped parameter model can be sufficient to satisfy the requirements for predicting containment pressure responses in the NHR200‐II design. However, further details of thermal–hydraulic phenomena and processes can be achieved through the distributed containment model, such as temperature distribution and fluid velocity within the containment. Notably, it was observed that heat transfer between the vapor and containment shell is a significant heat removal mechanism during the SBLOCA transients in the NHR200‐II. This finding emphasizes the importance of considering heat transfer through the containment shell in future analyses of containment response.