Abstract: Monitoring of Vibration of Reactor Internal Structures in Nuclear Power Plant(referred to as the standard hereafter), which will be issued by nuclear industry, concludes a new methods for a new type of nuclear power plant instrumentation and control system. This new system differs from the traditional monitoring systems, as it aims primarily at early failure detection. Useful information is provided to plant operators, but in particular to the inspection/maintenance personnel. The standard is used as an example for early failure detection and on-line condition monitoring methods based on signature analysis and feature vector monitoring in general.