Influence of boron enrichment in control rods on neutron-physical characteristics of the core of the reactor VVER

Boron is widely used in nuclear power as a neutron absorber material, thereby creating the possibility of controlling a nuclear reactor by changing the neutron multiplication factor. Natural boron contains about 20% 10 B and 80% 11 B with absorption sections respectively 3840 barn and 0.05 barn. The paper deals with changes in neutron-physical parameters of the reactor core of VVER type when the isotope content of 10 B in boron carbide of absorber rods (AR) of the control and protection system (CPS) and in boric acid solution in the coolant of the VVER reactor is varied, and also analyzes the practicality of increasing the enrichment of 10 B isotope in the control rods (CR). The model of VVER-1200 fuel assembly (FA) was used for calculations. In the course of work were modelled and the calculations of the three models of the coolant with different boric acid concentrations, as well as two models of AS with different enrichment in the isotope 10 B.