Most nuclear power plants (NPPs) built in the early stages were designed to operate at steady full power, known as ‘base-load’ operation. However, more and more nuclear power companies would like to have the flexibility to operate their NPPs depending on the load demand, which means to change how they operate from the base-load mode to flexible mode. Taipower company (TPC), the only utility in Taiwan, submitted an application for operating one reactor unit at a non-rated power level without changing the total rod power burnups in order to extend the operation period before next refueling outage. Since this was the first application, the Taiwan nuclear safety authority, Atomic Energy Council (AEC), thoroughly reviewed the impacts of the strategy by referring to the documents of flexible power operation experiences on nuclear power plants by the International Atomic Energy Agency (IAEA) and the US Electric Power Research Institute (EPRI). TPC plans to submit more applications to AEC in the near future. Both regulatory and operating experience feedbacks are important, since which are all good indicators to reflect whether the safety issues involved have been evaluated and/or the corresponding measures have been taken, if necessary.