Evolutionary simulated annealing for fuel loading optimization of VVER-1000 reactor

•ESA method was developed to improve original SA by using crossover and mutation operators.•Numerical calculations were performed based on a VVER-1000 MOX core using ESA and compared with SA and ASA.•The Mann–Whitney U test was conducted to compare the three methods.•The results show that ESA is advantageous over SA and ASA. An evolutionary simulated annealing (ESA) method has been developed for the problem of fuel loading optimization of VVER-1000 reactor. The ESA method improves original simulated annealing by using crossover and mutation operators to generate new trial loading patterns (LPs). A core physics calculation code for fuel LP optimization of VVER reactors (LPO-V) has been developed and verified based on a VVER-1000 MOX benchmark core in comparison with MCNP4c calculations. Calculations for optimizing fuel LP of the VVER-1000 MOX core have been conducted using the ESA method in comparison with simulated annealing (SA) and adaptive simulated annealing (ASA). Statistical differences between these methods were also evaluated based on the Mann–Whitney U test. The results show that the ESA method is advantageous over the SA and ASA.