Study on criticality and reactivity coefficients of VVER-1200 reactor

Highlights: • The criticality analysis of VVER-1200/V392M reactor core was performed. • The calculations were performed using MCNP5 code with ENDF/B-VII.0 data library. • The variation of coolant temperature and density on effective multiplication factor were deduced. • The evaluation of the reactivity coefficients were investigated. The numerical validation process is one of the important stages in reactor core design. In the present work, the criticality analysis calculations of VVER-1200/V392M reactor core was performed at first and second phases of initial fuel loading in cold, hot, and normal states. The calculations were carried out using MCNP5 transport code with ENDF/B-VII.0 nuclear data library, for core package and data library validation. The effect of different boric acid concentrations and the variation of coolant temperature and density, on the effective multiplication factor were investigated. Good agreements were observed between the previous measured values and the present calculated results of the effective multiplication factor. Furthermore, a preliminary limit for the boric acid concentrations at normal reactor operation state was deduced, along with full analysis of the reactivity coefficients of fuel and coolant temperatures, void, and boron concentrations. The analysis represents one of the first studies at which Monte Carlo transport code MCNP is accurately employed in modeling VVER-1200.