<p>During the start-up and shutdown of pressurized water reactor, the residual heat removal system is responsible for taking away the decay heat of the core. The fluid in the system before it is connected to the primary circuit are all at room temperature, far lower than the primary circuit temperature. Preheating of the system can effectively prevent thermal shock, which is of great significance to the integrity and reliability of residual heat removal system and primary circuit. The miniflow pipeline in the residual heat removal system is the important component of the system, which mainly consists of small size pipeline and venturi flowmeter. Under system preheating condition and unexpected conditions, such as and pump outlet isolation valve mistakenly closed, the pump only runs on the miniflow pipeline, which bears almost all the pressure drop of the system. Under these conditions the miniflow line should provide sufficient flow to ensure the reliable operation of the pump. Due to the high flow rate of the miniflow pipeline and the non-standard resistance module of the venturi flowmeter, the conventional fluid simulation analysis software cannot be used to analyze its resistance characteristics. In this paper, ANSYS-Fluent was used to conduct a complete modeling analysis of the miniflow pipeline, and corresponding characteristics of its flow and pressure drop were obtained, and further the flow of the pump under the relevant conditions were obtained. At the same time, the thermal stress caused by the mixing of hot and cold fluids between the miniflow pipeline and the main pipeline under the relevant conditions is analyzed. The analysis results show that the flow rate of the miniflow pipeline is greater than the required flow rate of the pump, and its thermal stress is reasonable and controllable,meeting the functional requirements of the system.</p>

Resistance and Thermal Stress Analysis of Miniflow Pipeline of Residual Heat Removal System in Pressurized Water Reactor

Paper Proceedings: https://asmedigitalcollection.asme.org/ICONE/ICONE28/volume/85246

2021 28th International Conference on Nuclear Engineering (ICONE28)

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