Abstract: Leakage from the refueling water tank bottom plate has gradually become a common issue in nuclear power plants. This paper first introduces the background and structural characteristics of refueling water tank leakage in nuclear power plants and explains the causes, common leakage forms, and currently used leak detection methods. Then, to address the existing problems of inaccurate and incomplete leak point identification, three improved and optimized leak detection methods are proposed: the reverse infiltration detection method, the vacuum box display method, and the positive pressure suction gun helium detection method. The advantages and application effects of these three improved leak detection methods in detecting leaks in refueling water tank bottom plates are analyzed in detail. Finally, the types and causes of bottom plate defects are discussed, and it is clarified that the plate-attaching repair method is currently the most effective means of rework. Directions for further research and optimization are also proposed.