Fig. 1. Flow chart of construction of ROM calculation

Fig. 2. Diagram of LFMSR primary loop(a) Geometry, (b) 2D spatial mesh

Fig. 3. Relative power variation of the core under transient conditions (a) Laminar, (b) Turbulence

Fig. 4. Normalized modal eigenvalue curves of velocity, pressure and flow resistance (a) Laminar, (b) Turbulence

Fig. 5. L² norm relative error of FV-ROM and SUP-ROM in different modes at laminar scenario (a) Velocity, (b) Pressure

Fig. 6. Absolute error of velocity and pressure field between FV-ROM and SUP-ROM at 350 s(a) Velocity (FV-ROM), (b) Velocity (SUP-ROM), (c) Pressure (FV-ROM), (d) Pressure (SUP-ROM)

Fig. 7. Single step time acceleration ratio of FV-ROM and SUP-ROM (color online)

Fig. 8. L² norm relative errors of FV-ROM and SUP-ROM in different modes at turbulent scenario (a) Velocity, (b) Pressure

Fig. 9. Absolute errors of velocity and pressure field between FV-ROM and SUP-ROM at 5 s(a) Velocity (FV-ROM), (b) Velocity (SUP-ROM), (c) Pressure (FV-ROM), (d) Pressure (SUP-ROM)

Fig. 10. Single step time acceleration ratio of FV-ROM and SUP-ROM (color online)