A method of operating a nuclear reactor includes operating a valve actuator to open and close a valve in fluid communication with a nuclear reactor fluid control system. The valve actuator includes a motor having windings of magnet wire. The magnet wire includes a layer of insulating material disposed over a conductor. The layer of insulating material comprises polyetheretherketone (PEEK) and has a thickness between about 0.025 mm and about 0.381 mm. A method of replacing a valve actuator motor with such a motor having windings formed of PEEK-insulated magnet wire is also disclosed. A method of coupling a valve actuator with such a motor having windings formed of PEEK-insulated magnet wire to a valve is also disclosed.