Reactivity coefficients simulation of the Iranian VVER-1000 nuclear reactor using WIMS and CITATION codes

Reactivity coefficients analysis of the Bushehr Nuclear Power Plant (BNPP), VVER-1000, at nominal conditions is carried out during its first operational cycle where we used WIMS and CITATION codes in our theoretical studies. Modelling of all rods (including fuel rods, control rods, burnable and non-burnable poison rods) and channels (including central guiding channel, central channel and reactor perimeters) is carried out using the WIMS code. Moreover, modelling of the fuel assemblies and reactor core is completed using the CITATION code. The multi-group constants generated by WIMS for different fuel configurations are fed into CITATION. The multi-group constants for fuel assemblies are obtained from the flux distribution calculated by the code. Then by putting fuel assemblies together to make up the core, and using the calculated constants, the core multiplication factor is calculated for different conditions. A FORTRAN 90 program is written to link the WIMS and CITATION codes and facilitate their numerous executions. Our calculated reactivity coefficients are comparable with the plant's FSAR.