In this paper, the water level control problem of U-Tube Steam Generators (UTSG) of Nuclear Power Plants (NPP) is addressed through the design of an innovative set-point function; hence, the original architecture of the controller is retained for easy industry acceptance. The set-point function is synthesized based on the inverse-control theory, which is able to improve the transient performance of the UTSG level subject to power adjustments. Based on the lead time between the power adjustment decision and the actual initiation of the adjustment, the proposed set-point function can apply appropriate control on the feed-water flow rate preemptively. This preemptive control action allows the steam generator to prepare itself for the upcoming power change, i.e., steam flow-rate change, to minimize the transient effects. Detailed design and simulation processes are described based on Irving UTSG model under the entire operating power range. The simulation studies have shown that the proposed scheme is capable of keeping the water level within the admissible range effectively. When compared with a swell-based set-point function, the proposed scheme can reduce the percentage overshoot and undershoot by as much as 35.4% and 69.7%, respectively.