The structure of the control rod is shown in Fig. 4.20. The “element” consists of B4C which is loaded in the refractory metal sleeve. The control rod (total length, about 3.1 m) is formed by axially connecting 10 elements using the connecting rod. The control rods are driven in pairs of two, and there are 16 pairs in total. The control rods is driven by hoisting the cable onto a drum using the control rod drive which is mounted in the stand pipe of the reactor pressure vessel. The control rods are inserted into the core from the top.

The reserve shutdown system is provided as backup to reactor shutdown system of the control rods. The reserve shut down system inserts negative reactivity into the core by dropping B4C pellets into the hole in the control rod guide column.

No optimization

Fuel temperature [ °С]

Fig. 4.21 Design of power distribution and fuel temperature distribution