Fig. 1. Overall calculational flowchart of NECP-Panda

Fig. 2. Fuel pebble refinement model

Fig. 3. Schematic diagram of calculation model for reflector group constants

Fig. 4. Schematic diagram of cylindrical geometric nodal

Fig. 5. Simplified reflector model with inner and outer control rods

Fig. 6. Schematic diagram of simplified mixed pebble bed reactor (a) X-Y view, (b) X-Z view, (c) Y-Z view

Fig. 7. Structure diagram of HTR-PM structure division (color online)

Fig. 8. Structure diagram of HTR-PM fine model(a) Radial view, (b) Axial view

Fig. 9. The integral value curve of 18 control rods