Calculation of reactivity coefficients with burn-up changes for VVER-1000 reactor

In this paper, the temperature reactivity coefficients of fuel and coolant are calculated. These coefficients are one of the important inherent factors in rector power control. We also calculated the reactivity coefficient of boric acid concentration and moderator density. All of these coefficients are calculated during burn-up changes to consider the effects of fission products build-up and fuel consumption. To perform neutronic calculations, the reactor core has been simulated using DRAGON4 and DONJON4. The thermal-hydraulic (T-H) calculation is performed using single heated channel model. The T-H model is implemented for VVER-1000 reactor as a computer program. These codes are coupled by development of an auxiliary computer program. The obtained results are compared with plant's FSAR that confirm the ability and reliability of the method.