Analysis of CHF characteristics with fuel rods in the natural circulation system under motion conditions

For the floating pressurized water nuclear reactor, CHF is vital to the fulfilment of design and operation criteria for safe performance and the safety of nuclear fuel, and natural circulation is the primary circulation in many designs. However, the traditional method of look-up table or correlations evaluation is no longer applicable to the CHF characteristics because of additional force in the motion conditions, especially in natural circulation system (Gui et al., 2021). In this study, the prediction of CHF under motion conditions is carried out with code development and experimental study. The theory of natural circulation system models, subchannel models, critical heat flux models are coupled together with motion models to establish the prediction model for fuel rod critical heat flux characteristics in the natural circulation system under motion conditions. As rolling motion is studied in the previous study (Huang et al., 2018), inclination and heaving conditions are two motion conditions that are mainly considered in this study. The inclining and heaving conditions are modeled by adding the additional motion force. The code calculated results are validated with experimental data. The calculation results are analyzed with different inclining and heaving conditions, and the regularity of CHF variation characteristics is illustrated.