Nuclear power is an important basis for building a clean and low-carbon new power system. However, this emerging power system is characterized by reduced system inertia and diminished disturbance resilience, introducing unclear risks to the grid-connected operation of nuclear power units. This paper first summarizes the characteristics of the new power system and discusses its influence on the stability of nuclear power units. Then, it introduces the basic operation characteristics and safe operation principles of nuclear power plants, while the interaction between nuclear power units and the power grid is also analyzed. Furthermore, this paper explores the potential grid-integration risks faced by nuclear power units under the new power system and presents risk assessment methods based on uncertainty analysis. Finally, it discusses strategies to mitigate these risks and proposes recommendations for optimal operation. This study aims to provide theoretical support and practical guidance for ensuring the safe operation of nuclear power units in new power systems.