The major goal of nuclear power industries during past 10 years has been increasing reliability and utility capacity factor. But as capacity factors crept upward, it became harder and harder to attain next percentage of improvement. Therefore, other innovative technologies and method are required. The monitoring, diagnostic and prognostic technologies have been applied to the fossil power plants and contributed a lot on improving their reliability and performance. However nuclear industries are still reluctant to apply the technology by several reasons. In this paper, current preventive maintenance status of nuclear power plants and industrial practice of monitoring, diagnostic and prognostic technologies are investigated. In addition, the restriction in the implementation of the technologies to the nuclear power plants are defined. Finally, we suggest appropriate methods of implementing the technology to nuclear industries for improving current reliability and performance.