Development of practical method using a Monte Carlo code for evaluation of optimum fuel pitch in a typical VVER-1000 core

► A new method to calculation optimum moderator-to-fuel ratio and fuel pitch using Monte Carlo code have been developed. ► The optimum fuel pitch is calculated using the MCNPX code for a typical VVER-1000 core. ► The calculations are validated using the reliable data of VVER-1000. ► The method can be used to calculate the fuel pitch in similar VVER-1000 reactors. ► The proposed method can be used as a benchmark for modifying models with less precision.