Fig. 1. Schematic diagram of natural circulation experiment loop with 5×5 rod bundle channel

Fig. 2. (a) Structural diagram of 5×5 rod bundle test section, (b) Schematic of cross section of rod bundle section and thermocouple layout, (c) Structural diagram of the heating rod and thermocouple layout

Fig. 3. Flowchart of the implementation process of neutronic-thermo-hydraulic coupling

Fig. 4. Power fluctuation curve with neutronic-thermo-hydraulic coupling under rolling motion conditions

Fig. 5. Fluctuation curves of thermal parameters with neutronic-thermo-hydraulic coupling under static conditions(t_sub=60 ℃, W=4 kW, k_c=-5×10^-4 ℃^-1, k_f=-5×10^-5 ℃^-1)

Fig. 6. Sensitivity analysis of temperature feedback coefficients of fuel and coolant (t_sub=40 ℃, W=4 kW)(a) Experimental results of different fuel temperature feedback coefficient, (b) Experimental results of coolant fuel temperature feedback coefficient, (c) Power standard deviation with different feedback coefficient

Fig. 7. Thermal parameters fluctuation curves after the introduction of -5×10^-5 reactivity disturbance (t_sub=40 ℃, W=8 kW)(a) Fluctuation curves of thermal power and reactivity, (b) Fluctuation curves of flowrate and temperature

Fig. 8. Thermal parameter fluctuation curve of single phase neutronic-thermo-hydraulic coupling under rolling motion condition (A10T10, t_sub=40 ℃, W=4 kW, k_c=-5×10^-4 ℃^-1, k_f=-5×10^-5 ℃^-1) (a) Fluctuation curves of flowrate and thermal power, (b) Fluctuation curves of pressure and pressure drop, (c) Fluctuation curves of temperature

Fig. 9. Reactivity fluctuation curve under rolling conditions (A10T10, t_sub=60 ℃, W=8 kW, k_c=-5×10^-4 ℃^-1, k_f=-5×10^-5 ℃^-1)

Fig. 10. The effect of the rolling parameters on the neutronic-thermal coupling of rod bundle with neutronic-thermohydraulic-motion coupling (a) Fluctuation curves of thermal power and real-time reactivity at different rolling periods (A15, t_sub=40 ℃, W=8 kW, k_c=-5×10^-4 ℃^-1, k_f=-5×10^-5 ℃^-1), (b) Fluctuation curves of thermal power and real-time reactivity at rolling amplitudes (t_sub=40 ℃, W=4 kW, k_c=-5×10^-4 ℃^-1, k_f=-5×10^-5 ℃^-1)

Fig. 11. Flow fluctuation behavior of natural circulation before and after the initiation of rolling motion (A20T25, P=0.3 MPa, t_sub=40 ℃, W=4 kW) (a) Transient process before and after the initiation of rolling motion without thermo-hydraulic coupling, (b) Transient process before and after the initiation of rolling motion with neutronic-thermohydraulic-motion coupling (k_c=-5×10^-4 ℃^-1, k_f=-5×10^-5 ℃^-1)