Abstract: This invention provides a method of operating a nuclear reactor having a negative reactivity moderator temperature coefficient with the object of maintaining a uniform and symmetric Xenon distribution above and below substantially the center of the core over a substantial axial length of the core during normal reactor operation including load follow. In one embodiment variations in the Xenon distribution are controlled by maintaining a substantially symmetric axial power distribution. The axial offset, which is employed as an indication of the axial power distribution, is maintained substantially equal to a target value, which is modified periodically to account for core burnup.