In recent years metaheuristic optimization algorithms have been widely developed. These algorithms are inspired from nature for solving complicated engineering problems. In this work, gravitational search algorithm (GSA) based on Newton's law of gravity is introduced for exergy optimization of the Bushehr nuclear power plant (BNPP). The main objective in this work is to minimize exergy destruction in the BNPP. In this analysis, beside the GSA, Genetic Algorithm (GA) is applied and the performances of these algorithms in two different cases are compared. In first case, the sphere function as a challenging optimization problem is investigated and it is demonstrated that the GSA has reliable fitness values (3.7602e-17). In the next case, the exergy destruction of the BNPP is studied and the exergy efficiencies of all components in the BNPP are evaluated. The reactor core (pressure vessel) and steam generator with 1511.35 MWth and 146.65 MWth of exergy destructions and irreversibility ratios of 50.34% and 4.88%, are introduced as the main irreversible components, respectively. The exergy destruction in the BNPP with the application of the GSA and GA is minimized and the optimum operating parameters in desired streams are reported. The exergy destruction of the BNPP (1968.95 MWth) is minimized to 1965.9 MWth. The results indicate the effectiveness of the GSA and it is shown that the method has robust high-quality solution for exergy destruction optimization. (C) 2018 Elsevier Ltd. All rights reserved.