The reactor core in a nuclear power plant has safety and economic significance. In terms of reactor control, using optimal control for reactor core in a nuclear power plant is an important step in improving safety and increasing its reliability and availability. The failure of a nuclear power plant in the desired control of the reactor core can lead to more operational costs or reduce the safety and reliability of the plant. In general, the reactor core control contains the power (or coolant temperature) control and axial power difference (power distribution) control of the core. In this paper, for the first time, an optimized PID controller is used in power maneuvering transients for the Tehran research reactor. PID controller gains are optimized (tuned) by Teaching–learning-based optimization (TLBO) method according to the minimization of a cost function. This function is based on the sum of the integral of absolute error (IAE) and overshoot. The reactor core is simulated based on the linearized fractional neutron point kinetics (FNPK) equations. The model obtains temperature feedbacks from lumped fuel and coolant. Xenon concentration changes are also considered. Simulation results indicate that the optimized control method is easy to implement and eliminates the overshoot and fluctuations, which is common in conventional control methods such as the Ziegler–Nichols tuning method. It has a faster response to load changes in power maneuvering transients. Therefore, improves the reliability and safety of the reactor.